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Food Control. Vol. 6, No. 1. pp. 4>52. 1945
Copyright 0 1995 Elscvier Science Ltd
Printed in Great Britain. All rights reserved
0956~7135/95 $lO.lM + 0.00
‘SOUS-VIDE'REVIEW
The sensory and nutritional
quality of ‘sous vide’ foods
Philip G. Creed
The sensory quality of ‘sous vide’ foods was the main factor which brought it to
international attention before the microbiological risks became prominent. Few
data are available which are consistent and provide quantitative scientific evidence
for this method’s undoubted gastronomic appeal. Similarly, fewer data are
available to support the supposed superiority in retention of vitamins. The wide
range of products, processing conditions, processing equipment, methods for
assessing sensory and nutritional quality calls for a more holistic approach to
research. This paper reviews the objective work done so far and raises questions
which need to be answered in order to help the method gain wider acceptance.
Keywords: sous vide; sensory; nutrition; quality; vitamins; research needs
INTRODUCTION
Since 1984 the ‘sous vide’ method has received a large
amount of coverage in the technical press with applica-
tions ranging from commercial and institutional cater-
ers, in-flight catering and schools, to retailers and food
processors. Most coverage has concentrated on the
risks of food poisoning and the steps needed to ensure
the safety of the process but a significant proportion has
shown an almost evangelical attitude towards the im-
proved sensory and nutritional qualities of sous vide
foods compared to those produced by conventional
means. The comments from some of these sources
(shown in Table I) provide ample anecdotal evidence
that the sous vide method produces food of a high
sensory quality with the added supposition that its
nutritional qualities must be equally high. However,
there is, as yet, little evidence for these opinions which
can be supported by objective and scientific experi-
ment.
Table I can be summarized in the statement that the
sous vide method produces a food with a better flavour,
Department of Service Industries, Bournemouth University,
Wallisdown, Poole, Dorset, BH12 5BB, UK. Presented at
the First European ‘Sous Vide’ Cooking Symposium 25-26
March 1993, Leuven, Belgium. Received 1 August 1993;
revised 3 March 1994; accepted 21 March 1994
colour, texture and nutrient retention that conven-
tionally cooked foods. It should, however, be remem-
bered that this evidence is put forward mostly on the
basis of professional judgement by those who have
already made a commitment to the sous vide method in
time, resources and capita1 expenditure.
This paper aims to outline methods available to
provide the scientific evidence, to review the scientific
evidence gathered so far and to suggest some of the
questions which need to be addressed by future re-
search projects.
TECHNIQUES FOR ASSESSING THE
SENSORY QUALITY OF FOOD
Sensory analysis has advanced greatly in recent years
and is now regarded throughout manufacturing and
research as an objective science. A number of factors
have contributed to this advancement, including im-
proved training programmes for sensory assessors,
expansion of the range of sensory tests available, a
greater range of availability of statistical techniques for
data analysis and the introduction of sophisticated
computer software packages, particularly in graphical
representation, which has led to improved interpreta-
tion and presentation of the results of sensory analysis.
Food Control 1995 Volume 6 Number 1 45
Quality of ‘sous vide’ foods: P.G. Creed
Table 1 Examples of the subjective and anecdotal evidence for the sensory and nutritional qualities of sous vide foods
Comment
‘ . no flavour is lost into the surrounding water or steam . . .’
‘
. . . retains all of its natural flavour, along with more of its nutritional qualities . . .’
‘ . . . the food retains all its flavours and fresh taste . . .’
‘
. . . all the nutrients, flavor, texture and aroma of the food are locked in . . .’
’ . . . raw or lightly cooked food product retains almost all its color, flavor and nutrients . . .’
’ . . . enhances flavor and aroma . . .’
‘ . . . the integrity and taste of the food is generally considered superb . .’
‘ . . . the best lamb they’d ever tasted . . .’
’ . . . tasted like real food . . .’
’ . . . the process intensifies flavour . .’
’ . . . superiority of flavour and natural nutrient retention . . .’
‘ . . . food that tastes like it was freshly made . . .’
‘
. . . the flavours can’t escape . . . more taste and smell . . . the texture of the food is constant . . .’
‘ . . . seals in flavour, juices and nutrients . . .’
‘ . “sous vide” . . . products are rightly seen by the consumer as providing enhanced convenience and
improved eating quality.’
‘ * . . does not harm the color, texture or flavour of food . . .’
‘ * . . its flavour is highly praised in haute cuisine circles . . .’
’ . . . retain flavouring . . reduce the loss of vitamins and nutrients in the cooking process . , .’
’ . . . the quality of the final products are often far superior to foods prepared in the traditional manner.’
‘ . . . flavour and tenderness are enhanced . . .’
Reference
Anon., 1987a
Anon., 1987b
Bacon. 1990
Baird,‘1990
Bertagnoli, 1987
Ivany, 1988
Kalinowski, 1988
Levine and Rossant, 1987
Levy, 1986
Manser, 1988b
Nanleton. 1991
Pet&, 1998
Pring, 1986
Raffael, 1984
Richmond, 1990
Sarpa, 1988
Sellers. 1990
Sessions, 1987
Somay, 1990
Stacey, 1985
Collectively, these advances allow the sensory
analyst to construct models or images of products, to
relate the results of laboratory tests to acceptability
ratings from consumer studies and to predict the effect
of changes in a product’s sensory profile on consumer
acceptability. Many techniques are available which
enable the investigation of the sensory properties of
products ranging from simple difference tests to com-
plex descriptive techniques.
Several books have provided outlines of how and
when the various tests should be used as well as updates
in the field of sensory analysis (Amerine et al., 1965;
Piggott, 1988; Thomson, 1988). The objectives of these
tests can be summarized as follows:
using difference tests to locate and identify differ-
ences between products or dishes;
applying descriptive analysis to describe products
quantitatively in terms of their sensory attributes
and display graphically the results in two- and three-
dimensional models;
using preference/acceptability tests to identify and
quantify consumer acceptability for products;
relating results from descriptive analysis and accept-
ability tests to predict consumer responses to
changes in products by identifying those sensory
attributes contributing to the direction and magni-
tude of the response;
applying time-intensity measurements to investigate
the appearance, duration, disappearance and linger
of sensory attributes thereby assessing their relative
contribution to the eating experience.
Difference tests would be appropriate to determine
simply if a dish cooked traditionally could be distin-
guished from the same dish cooked using the sous vide
method. They would not, however, enable the investi-
gator to know what those differences were or their
magnitude on an absolute scale. Techniques for this
would involve quantitative descriptive analysis (QDA)
which enables more information to be gathered (Stone
et al., 1974). Powers (1988) gives an outline of descrip-
tive methods including QDA, which he defined as:
‘developing a list of descriptive terms, screening would-
be assessors for possible membership of a panel, train-
ing judges, using sufficient replication so that the
performance of the assessors, the effectiveness of de-
scriptive terms, product differences and possible in-
teraction effects may be isolated and evaluated by
statistical analysis, and expressing the results graphical-
ly as well as numerically.’
Stone and Side1 (1985) give procedures of the first
stage of screening assessors, testing their ability to rank
the basic tastes, identifying odours and discriminating
differences as preliminaries to selection for using
QDA. The second phase of training involves explaining
the purpose of the method, the human mechanisms for
sensing taste, odour, colour and texture, using descrip-
tions from a standard vocabulary and standard scoring,
the conditions used for testing and how the standard
vocabulary can be devised in order to construct the
forms used for scoring food products. Rutledge and
Hudson (1990) and Rutledge (1992) have also provided
guidance.
The QDA technique has been used for: beer (Miel-
gaard et al., 1979; Mecredy et al., 1974), wine (Vedel et
al., 1972), whisky (Shortreed et al., 1979), strawberries
(Shamaila et al., 1992), apple juice (Dtirr, 1979), cider
and perry (Williams, 1975), and apples (Williams and
Carter, 1977).
SENSORY QUALITY OF CHILLED FOODS
Several reviews have covered chilled foods but there is
only one specifically on the sous vide method (Leadbet-
ter, 1989) which concentrated on the microbiological
hazards but also provided a brief history of sous vide
and its preceding related systems [Nacka (Bjorkman
46 Food Control 1995 Volume 6 Number 1
Quality of ‘sous vide’ foods: PG. Creed
and Delphin, 1966), AGS (McGuckian, 1969) and
Capkold (Daniels, 1988)], packaging, equipment and
the benefits of the system.
Other reviews on the use of precooked chilled foods
in catering have also covered food produced by the sous
vide method: Robson & Collison (1989) reviewed
sensory aspects; Glew (1990) covered sensory, nutri-
tional and microbiological aspects, somewhat mis-
takenly outlining the method as being in use for the last
30 years and a variant of the now obsolete Nacka
system, in preventing the loss of flavour volatiles and
the over-cooking of delicate products such as fish;
Mason et al. (1990) reviewed the sensory aspects of
chilled foods, concluding that vacuum-packing may
decrease juiciness and that the potential for enhancing
the eating quality of particular products was real but
exaggerated by the popular and catering press. They
also highlighted the problems of comparing sensory
studies due to the lack of standardization in product
preparation, assessors, experimental design and test
design: a comprehensive chapter on the sous vide
method was also included in an extensive book on the
technology and management of cook-chill catering
(Light and Walker, 1990).
General studies on chilled foods included work by
Turner et al. (1984) who studied cabbage, peas, pota-
toes (four types) in hospital conventional, cook-chill,
cook-freeze and cook-freeze-thaw systems producing
data on colour, appearance, odour, taste and texture
which allowed classification of samples into quality
classes for easier comparison. This last idea of quality
classes from Zacharias (1980) indicated the extent of
the decline in sensory qualities during chilled storage.
SENSORY QUALITY OF SOUS VIDE FOODS
Two pieces of work (Light et al., 1988; Schafheitle and
Light 1989a) studied the microbiological and sensory
quality of some chicken, fish and vegetable dishes
produced by the sous vide method and were summa-
rized by Light and Walker (1990) and Schafheitle and
Light (1989b).
The work by Light et al. (1988) based on earlier work
by Schafheitle et al. (1986) showed that chicken a la
king was acceptable up to 14 days but courgettes
provencale only up to 7 days and also suggested that the
possible enhanced nutritional quality of sous vide food
should be examined. A consumer panel was used to
discriminate between fresh and samples stored for 7, 14
and 21 days. This implicitly assumed that there was no
initial variation in the raw materials used for cooking
conditions between the samples freshly prepared for
each comparison at the different times. The trained
panel assessed several characteristics - pungency, crisp-
ness, strength of flavour etc. as appropriate for the two
dishes - to give mean quality scores at different storage
times. However, no statistical evidence was provided to
show if the differences in scores were significant.
Later work by Schafheitle and Light (1989a, 1989b)
showed that chicken ballotine remained acceptable for
up to 21 days stored at 13°C that the stored product
was found to be different from the freshly produced
dish using the Triangle Test but little difference was
found using descriptive analysis - this outcome is
somewhat surprising as it is generally agreed that a
trained panel used for descriptive analysis would be far
more discriminating than an untrained panel used for
Triangle Tests (Pierson, personal communication,
1992). It was also concluded that combination ovens do
not provide even heat transfer over all parts of the oven
[c.f. work by Sheard and Church (1992) on variation in
oven performance] and that more research is required
on processing conditions, microbiological safety and
migration of substances from the packaging to the food.
Again it was assumed implicitly that there was no initial
variation in the raw materials used for producing the
fresh controls on the five separate occasions for the
Triangle Tests. However, the times that the food was
held at 80°C (the chosen pasteurization temperature)
varied from 8 to 23 min, having already taken from 15
to 39 min to attain this temperature. This variation in
heating conditions and the possible variation in raw
material could have been the reason for the mean
scores for appearance, odour, juiciness, flavour, chick-
en and vegetable texture showing no significant differ-
ence with an increase in chilled storage time from 0 to
21 days [except for the appearance at 14 days (p =
0.033) showing a poorer aspect]. The mean scores
were, however, all at the positive end of the scale used.
Church (1990) provided brief details of comparative
trials where a significantly large proportion of assessors
could distinguish sous vide from traditionally cooked
chicken ballotine, vegetable rice and dauphinoise pota-
toes. This was confirmed by QDA as differences in
‘chicken juiciness, filling moistness, initial flavour and
aroma depth’. It was not stated if these differences
were statistically significant.
Smith and Fullum-Bouchard (1990) compared chick-
en veloute prepared in cook-chill, cook-freeze and sous
vide systems with a fresh sample at 1, 3 and 6 days
storage at 4°C or -14°C and found no significant
differences in aroma, appearance, flavour and tender-
ness.
Gittleson ef al. (1992) assessed the sensory qualities
of commercially produced sous vide salmon packed in
two types of plastic packaging. Using QDA techniques,
colour, flakiness, crumbliness, fish odour and overall
acceptability were measured on nine-point scales over
the 100 days of storage in ice at O-&C. Overall accepta-
bility was found to be negatively correlated with fish
odour and was satisfactory up to 12 weeks of storage
(p<O.Ol). Instrumental texture measurements of shear
force value (Instron machine, Instron Corp., Canton,
MA, USA) showed no significant difference between
package types possibly due to product variability and
maintaining the orientation of the fish muscle between
the shear blades.
Other work in Australia on sirloin, lamb, pork loin,
turkey breast, chicken mousse and various vegetables
Food Control 1995 Volume 6 Number 1 47
Quality of ‘sous vide’ foods: P.G. Creed
included measurement of acceptability using eight fac-
tors for storage up to 4 weeks (Grant, personal com-
munication, 1992).
As part of a study on the use of irradiation on sous
vide products, chicken breasts were assessed for off-
flavour and odours by Shamsuzzaman et al. (1992). It
was found that the electron beam treatment had little
effect on these two factors up to 55 days of storage at
2°C whereas untreated packs had spoiled between 30
and 42 days of storage.
In recent unpublished work at Bournemouth Univer-
sity, multi-component foods (chicken/prawn, chicken/
bacon/pepper, haddock, minced lamb) encased in
pastry with sauce were vacuum-packed in trays on an
automatic machine, pasteurized and stored chilled (O-
3°C) or frozen (-18°C) for one week. No difference
was found between chilled and frozen samples on
scores for the acceptability of appearance, flavour,
texture and aftertaste: all scores except for the lamb
being at least 4.5 on a six-point scale - a level deemed
satisfactory.
Informal taste panels have been conducted by Levy
(1986) and Manser (1988a) on sous vide products
provided by Home Rouxl. Levy commented favourably
on the texture of scallop and chicken liver mousses and
the flavour of brill, fish mousse and poulet chasseur but
unfavourably on vegetable dishes. Manser commented
favourably on the intensity of flavour of carrots and
lamb and all the sensory attributes of duck breast.
RELATED METHODS
Two processes directly related to the sous vide method
through the process of vacuum packing followed by
cooking also provide relevant sensory data. The first
described by Poulsen (1978) is the production of ready-
cooked vacuum packed potatoes pasteurized at 9%
98°C for 40 min, cooled and stored at 0-5°C. The
sensory data from Triangle Tests showed no preference
for ready-cooked vacuum packed potatoes when com-
pared with those normally prepared but a marked
preference over canned potatoes.
The second process, known as the cook-in-bag sys-
tem, has been applied mainly to meats. One study
(Jones et al., 1987) included comparisons between
control pork roasts wrapped in PVC, stored at -20°C
then cooked conventionally and roasts vacuum packed,
cooked to 70°C in a 100°C water bath then stored for 14
and 28 days at 4” or -20°C then reheated. At 28 days,
the frozen stored roasts were less juicy than the control
and chilled stored roasts (p<O.O5); the tenderness of
frozen stored roasts decreased over the period
(p<O.O5); the intensity of pork flavour of the chilled
stored roasts also decreased and again the intensity of
off-flavour and Warner-Bratzler shear values did not
differ significantly (p>O.O5) over the storage period.
Commercially produced turkey breast rolls prepared
by vacuum packing and then cooked to an internal
temperature of 71°C were studied over 87 days storage
at 4°C. Warner-Bratzler shear values from rolls pro-
duced at one of the two factories decreased significantly
(pcO.05) (Smith and Alvarez, 1988).
Buck et al. (1979) found that vacuum-packed beef
roasts cooked to 60°C in a water bath at 60-61”C were
significantly more tender (p<O.Ol) than matching
roasts cooked to the same temperature in a convention-
al oven at 94°C scoring on average 6.1 and 4.4,
respectively, on an eight-point scale.
In other work, beef chuck roasts were vacuum
packed and then heated to 65°C in a 71°C water bath
and compared with conventionally cooked roasts. No
significant differences in cooking loss, tenderness, juici-
ness, intensity of beef flavour and off-flavour or
Warner-Bratzler shear values were observed (p>O.O5)
either immediately or after storage for 14 to 28 days at
4°C. The only significant change was in the intensity of
beef flavour of the vacuum-packed roasts which de-
creased (pcO.05) (Stites et al., 1989).
TECHNIQUES FOR QUANTIFYING
NUTRIENT RETENTION
Quantifying the nutritional content of foods has long
been of interest to many areas of human medicine and,
more recently, due to requirements for nutritional
labelling which may eventually cover cooked and chil-
led meals such as sous vide produced for sale to third
parties.
The vitamins of interest in this case will be those
which are liable to decrease during the sous vide
processing method, i.e. those sensitive to heat treat-
ment: thiamin (vitamin B,), riboflavin (vitamin Bz) and
ascorbic acid (vitamin C). Losses of minerals are not
caused by heat but can occur by leaching into cooking
water (British Nutrition Foundation, 1987). In the case
of the sous vide method, the mineral content of the
fresh food would probably be maintained. Calcium and
sodium, for example, are both of interest to the con-
sumer as regards maintaining an adequate supply of the
former and limiting the intake of the latter.
VITAMIN DETERMINATION
The strengths and weaknesses of various methods for
determining the vitamin content of foods have been
discussed by Lumley (1993), Eitenmiller (1990) and
Gregory (1983). These methods include chemical
methods such as: thiochrome for thiamin; microbiolo-
gical methods where the dose response of microorgan-
isms is measured; the radioimmume (enzyme-linked
immunosorbent assay, ELISA) method of limited use;
the time-consuming biological methods based on the
growth response in rats and chicks and high perform-
ance liquid chromatography (HPLC) deemed to be the
most developed and advancing method.
Many HPLC methods have been devised to deter-
mine the amount of vitamins and other substances
48 Food Control 1995 Volume 6 Number 1
Quality of ‘sous vide’ foods: P.G. Creed
Table 2 Percentage retention of vitamins in sous-vide processed
meat and fish dishes (adapted from Watier, 1988)
Vitamin Beef Veal Lamb Pork Salmon Cod
Vitamin B1 70 91 77 90 90 85
Vitamin Bz 100 52 100 100 100 63
Vitamin B6 100 100 100 100 85 100
Pantothenic acid 100 100 100 100 96 89
Vitamin B12 87 100 100 100 92 72
Biotin 100 100 93 100 95 95
Vitamin A - - - 78 67
ventional, cook-chill, cook-freeze and cook-freeze-
thaw systems, producing data on vitamins B,, B2 and
C. Hunt (1984) reviewed nutrient losses in cook-chill
and cook-freeze systems and concluded that vitamin C
losses in cook-chill were not when with large compared
conventional systems. Bognar (1990) provided the most
recent data in this area producing data on the vitamin
loss chilled of fruit and and during storage vegetables
the influence of chilling, storage and reheating condi-
tions on prepared foods.
present in food (Saxby, 1978). A very wide range of
foods have been analysed using different extraction
procedures to determine various combinations of vita-
mins. Examples of its use have been reviewed by
Polesello and Rizzolo (1986) for water-soluble vitamins
and more recently by Van Niekerk (1988).
Most vitamin determinations using HPLC have
analysed meal components with few analyses of pre-
pared dishes such as those provided by the sous vide
method. The only two examples found using HPLC for
analysis are for white sauce (Nandhasri and Suksang-
pleng, 1986) and turkey bologna (Tuan et al., 1987).
Other determinations of vitamins in foods such as meat
loaf (Dahl and Matthews, 1980), beef patties, fried fish,
(Ang et al., 1978), pot roast and gravy, beans and
frankfurters (Ang ef al., 1973, beef stew, chicken g la
king, shrimp Newburg, peas in cream sauce (Kahn and
Livingston, 1970), cod au gratin (Jonsson and Daniels-
son, 1981), Italian spaghetti (Khan et al., 1982), beef
stew (Nicholanco and Matthews, 1978) and pork cas-
serole in retort pouches (Uribe-Saucedo and Ryley,
1982) generally made use of chemical methods recom-
mended by the Association of Analytical Chemists
(AOAC, 1984).
RESEARCH ON THE NUTRITIONAL
QUALITY OF CHILLED FOODS
Little nutritional data is available on chilled foods
prepared by the sous vide method but a large amount is
available on changes occurring during processing (Ben-
der, 1987) and foods prepared in cook-chill systems of
which the sous vide method can be considered a
variant. Bognar (1980) studied the vitamin A, B1 and
B2 content of chilled meals prepared conventionally or
by cook-chill, cook-freeze or sterilization methods as
affected by chilling, storage and reheating conditions.
Later worked on cook-chill systems found changes in
vitamin content but not in the protein, fat, carbohy-
drates or mineral content of chilled and pasteurized
chilled meals after 10 and 28 days storage at 2°C
followed by reheating (Bognar et al., 1990). Data are
available for many types of products at various times:
sampled raw, just after cooking, just after cooling,
during chilled storage, just after reheating and at the
point of service.
The work of Turner et al. (1984) included studies on
cabbage, peas, potatoes (four types) in hospital con-
NUTRITIONAL QUALITY OF SOUS VIDE
FOODS
The earliest work aimed specifically at sous vide food
(Buckley, 1987b) studied the stability of vitamin C in
broccoli in a simulated sous vide system, finding that
leaching and oxidation were avoided. The simulation
consisted of cooking in a ‘pressure steamer for 4 min’.
This would provide a temperature above 100°C and so,
strictly speaking, would not be considered as a sous
vide process. However, the results showed 86% reten-
tion of vitamin C, compared with the raw product after
5 days chilled storage. Broccoli boiled or pressure-
steamed showed retention figures of 28 and 62%,
respectively, after 1 day of chilled storage, falling to 9.4
and 7.3%, respectively, after 5 days storage. The
method of determining vitamin C was described earlier
(Buckley, 1987a).
The most extensive work has been done in France
(Watier, 1988; Watier and Belliot, 1990) and summa-
rized by Watier and Belliot (1991). They studied the
retention of the B vitamins in beef bourguignon, roast
veal, roast lamb, roast fillet of pork, salmon and cod
(Watier and Belliot, 1990) and of vitamin C, B1 and
folates in potatoes, carrots, green beans and cauliflow-
er (Watier, 1988). Their results are summarized in
Tables 2 and 3. Comparisons were made with retention
values from the literature and it was concluded from
this that the sous vide method preserved ‘vitamins
liable to oxidation better than traditional cooking, but
this advantage was removed by storage and subsequent
reheating’. This work has therefore not made a direct
comparison between the same food cooked traditional-
ly and that cooked by the sous vide method but does
provide a guide to the influence of the sous vide
method on vitamin retention in food.
Table 3 Percentage retention of vitamins in sous-vide processed
vegetables after cooking, storage for 21 days and reheating (adapted
from Watier and Belliot, 1990)
Vitamin Potatoes Carrots Green beans Cauliflower
Carotene - 89 100
Vitamin E - 100 100
Vitamin C 63 86 40 69
Vitamin B, 86 67 86 56
Vitamin BZ 100 100 71 86
Vitamin Bh 80 100 79 63
Food Control 1995 Volume 6 Number 1 49
Quality of ‘sous vide’ foods: P.G. Creed
Smith and Fullum-Bouchard (1990) determined the
vitamin C content using HPLC in the spinach compo-
nent of chicken veloute prepared in cook-chill, sous
vide (storage at 4°C) and cook-freeze systems (storage
at -14°C) over 6 days, finding a decrease over the
whole period for cook-chill samples and a decrease
over the last half of storage for sous vide and cook-
freeze samples.
As part of a study on the use of irradiation on sous
vide products, the thiamin content of chicken breast
was determined using HPLC (Shamsuzzaman et al.,
1992). It was found that sous vide cooking produced
98% retention based on the raw value (1.07 pg/g);
increasing the electron beam treatment up to 2.9 kGy
decreased this value to 86% ; after 27 days storage at
2”C, these figures fell to 87% and 80%, respectively.
Other information on the retention of vitamins in
sous vide foods has been quoted by Bognar et al.
(1990). Although presented as figures relating to aspar-
agus, broccoli in cream sauce, broccoli and chicken B la
king produced by the sous vide method, the references
cited (Kraxner, 1981; Erdmann and Klein, 1982; Ezell
and Wilcox, 1959) provide no relevant data. For some
data, it is likely that the authors intended to refer to
Kossovitsas et al. (1973), who compared the quality of
prepared meals (broccoli in cream sauce, chicken B la
king and cod in cream sauce) held in chilled and frozen
storage. This data, was based on the ‘Nacka’ method of
preparation, so cannot provide a reliable estimate for
the sous vide method. Bognar et al. (1990) also quote
thiamin losses of 20-30% in sous vide processed roast
beef joints (Cooksey et al., 1988) and 10% for vacuum-
packed chicken and broccoli (Kraxner, 1981). The
usefulness of the latter data are again doubtful.
Work has also been done on ready-cooked vacuum
packed potatoes (Poulsen, 1978). The method follows a
similar procedure to sous vide, so that the nutritional
results might be relevant. The vitamin C content fell
from 26.8 to 24.9 mg/lOO g, a retention figure of 93%
compared to a cited figure of 62% for boiled potatoes.
Vitamin B1 fell from 77.6 to 73 pg/lOO g, a retention
figure of 94%.
No changes in the content of protein, fat, carbo-
hydrates and minerals in foods produced by the sous
vide method would be expected but some data is
available on commercially produced turkey breast rolls
prepared by the cook-in-bag process by vacuum pack-
ing and then cooking to an internal temperature of 71°C
and stored for 87 days at 4°C. The only significant result
was that amino nitrogen, non-protein nitrogen and pH
did not change (p>O.O5) over the storage period (Smith
and Alvarez, 1988).
CONCLUSIONS
The main point arising from the previous sections
indicates a lack of consistent information on the sen-
sory and nutritional qualities of foods produced by the
sous vide method which can be related to the proces-
50 Food Control 1995 Volume 6 Number 1
sing conditions of temperature and time which will
produce a safe product. The information available
covers a wide range of products, processing conditions,
methods for assessing sensory and nutritional quality
and includes data with inherent variability. The latter
could be present in the product itself, the processing
conditions, the skills of the researchers (not all food
scientists or technologists are chefs or all chefs scien-
tists) and the difficulties of experimental design itself.
This lack of information is one possible reason for the
relatively slow market penetration and take-up of the
sous vide method in the UK and elsewhere.
The first European Sous Vide Cooking Symposium
could be the first step towards a wider cooperation
between researchers working in this area of food
technology. The exchange of information and collab-
oration to avoid duplication of effort and to ensure
consistent methods for product evaluation should be
encouraged, although with commercial considerations
this may not always be possible.
Methods for quantifying nutrient retention and sen-
sory qualities are now well developed and feasible for
dishes prepared by the sous vide method. This means
that it is possible to ask some fundamental questions
which will draw together in a systematic and holistic
way the strands of food safety, sensory quality, nutri-
tional quality, consumer acceptance, process and
equipment development and the skills of the profes-
sional chef. These questions might be:
Is a dish prepared by the sous vide method signifi-
cantly better in sensory qualities and nutrient reten-
tion than the same dish prepared conventionally
under optimum conditions? If so, does the heating
treatment this entails pasteurize the food adequate-
ly?
How would any improvement in sensory qualities
and nutrient retention over the same dish prepared
conventionally be modified by chilled storage and
reheating?
Would any improvement in sensory qualities and
nutrient retention over the same dish prepared con-
ventionally be negated by frozen storage rather than
chilled storage?
How would any improvement in sensory qualities
and nutrient retention over the same dish prepared
conventionally be modified by the method of reheat-
ing?
How do different food components and meals in-
teract with each other and the food packaging to
affect the outcomes of the previous questions?
These questions need to be answered with regard to
those dishes most available commercially. A study of
the range of products offered by seven producers of
sous vide foods in the UK, Ireland, France and the
USA show that chicken-based dishes closely followed
by fish-based dishes and vegetables are most readily
available (Creed, unpublished data, 1992). These dis-
hes also seem to be those which might be generally
regarded as part of a ‘healthy’ eating regime and so the
Quality of ‘sous vide’ foods: P.G. Creed
study of their vitamin retention would be even more
appropriate.
This review has aimed to highlight the gaps in
knowledge relating to the sensory and nutritional
aspects of foods prepared by the sous vide method. It
also makes some basic proposals on research areas
which, when completed, will enable the sous vide
method to gain a solid foundation of scientifically
reliable knowledge.
ACKNOWLEDGEMENTS
Church, LJ. (1990) An Introduction to ‘Method Sous-Vide’ Depart-
ment of Hospitality Management, Leeds Polytechnic, 46 pp.
Cooksey, D.K., Klein, B.P. and McKeith, F.K. (1988) Effect of
packaging process on thiamine retention and other characteristics
of pre-cooked vacuum packaged beef roasts. Paper No. 653
presented at IFT Annual Meeting, New Orleans, June 1988
Dahl, C.A. and Matthews, M.E. (1980) Cook/chill foodservice system
with a microwave oven: thiamin content in portions of beef loaf
after microwave heating. J. Food Sci. 45, 608-612
Daniels, D. (1988) Sous vide and Capkold - two approaches to
cooking ‘under vacuum’. The Consultant 21 (2) Spring, 26-28
D&r, P. (1979) Development of an odour profile to describe apple
juice essences. Lebensmitt.-Wissensch. Technol. 12, 23-26
EitenmiBer, R.R. (1989) Strengths and weaknesses of assessing
vitamin content of food J. Food Qual. 13, 7-20
The author gratefully acknowledges the financial assist-
ante of British Gas, Unilever Research and Home
Roux1 in this work.
Erdmann, J.W. and Klein, B.P. (1982) Harvesting, processing and
200, (Ed;. P.A. Seib and B.M. Tolber) American Chemical
Society, pp. 499-532
cooking influences on vitamin C in foods. In: Ascorbic Acid:
Chemistrv. Metabolism and Uses Advances in Chemistrv Series
REFERENCES Ezell, B.D. and Wilcox, M.S. (19.59) Loss in vitamin C in fresh
vegetables as related.to wilting anh temperature. J. Agric. Food
Chem. 7, 507-509
AOAC (Association of Analytical Chemists) (1984) Official Methods
of Analysis 14th Edn, Washington, DC
Amerine, M.A., Panghom, R.M. and Roessler, E.B. (1965) Principles
of Sensory Evaluation Academic Press, London
Ang, C.Y.W., Chang, C.M., Frey, A.E. and Livingston, G.E. (1975)
Effects of heating methods on vitamin retention in six fresh or
frozen prepared food products. J. Food Sci. 40, 997-1003
Ang, C.Y.W., Basillo, L.A., Cato, B.A. and Livingston, G.E. (1978)
Riboflavin and thiamine retention in frozen beef-soy patties and
frozen fried chicken heated by methods used in food service
operations. J. Food Sci. 43, 1024-1025, 1027
Anon. (1987a). Cooking in a vacuum. Hospital Caterer January, p. 14
Anon. (1987b). Sealed with a hiss. Meat Process. July, p. 66
Bacon, F. (1990). Working to Rouxl. Cuterer Hotelkeeper 22 Febru-
ary, pp. 45-47
Baird, P. (1990) Sous vide: What’s all the excitement about? Food
Technol. 44, (11) 92, 94, 96
Bender, A.E. (1987) Nutritional changes in food processing. In:
Developments in Food Preservation - 4, (Ed. S. Thorne) Elsevier
Applied Science, London, pp. l-34
Bertagnoli, L. (1987) Pouches gain ground in food service. Res-
taurants Institutions 97 (lo), 29 April, pp. 178-180, 184
Bjorkman, A. and Delphm, K.A. (1966) Sweden’s Nacka hospital
food system centralizes food preparation and distribution. Cornell
Hotel Restaurant Admin. Q. 7 (3), 84-87
Bognar, A. (1980) Nutritive value of chilled meals. In: Advances in
Catering Technology (Ed. G. Glew) Applied Science Publishers,
London, pp. 387-408
Bognar, A. (1990) Vitamin status of chilled food. In: Processing and
Quality of Foods Vol. 3 Chilled Foods - the Revolution in
Freshness (Eds. P. Zeuthen et al.) Elsevier Applied Science,
London, New York, pp. 3.85-3.103
Bognar, A., Bohllng, H. and Fort, H. (1990) Nutrient retention in
chilled foods. In: Chilled Foods - The State of the Art (Ed. T.R.
Gormley) Elsevier Applied Science, London, New York,
pp. 305-336
British Nutrition Foundation (1987) Food Processing - a Nutritional
Perspective. Briefing Paper No. 11. 38 pp.
Buck, E.M., Hickey, A.M. and Rosenau, J. (1979) Low-temperature
air oven vs a water bath for the preparation of rare beef. J. Food
Sci. 44, 1602-1605, 1611
Buckley, C. (1987a) The vitamin C content of cooked broccoli. Hotel
Catering Res. Centre Lab. Rep. No. 238, Huddersfield
Polytechnic, 6 pp.
Buckley, C. (1987b) Storage stability of vitamin C in a simulated
sous-vide process. Hotel Catering Res. Centre Lab. Rep. No. 240,
Huddersfield Polytechnic, 2 pp.
Gittleson, B., Saltmarch, M., Cocotas, P. and McProud, L. (1992)
Quantification of the physical, chemical and sensory modes of
deterioration in sous-vide processed salmon. J. Foodservice Syst
6, 209-232
Glew, G. (1990) Precooked chilled foods in catering. In: Processing
and Quality of Foods Vol. 3 Chilled Foods - the Revolution in
Freshness (Eds. P. Zeuthen et al.), Elsevier Applied Science,
London, pp. 3.31-3.41
Gregory, J.F. (1983) Methods of Vitamin Assay for Nutritional
Evaluation of Food Processing. Food Technol. 37 (l), 75-80
Hunt, C. (1983) Nutrient losses in cook-freeze and cook-chill cater-
ing. Human Nutrition: Applied Nutrition 38A, SO-59
Ivany, L. (1988) Perry promotes sous vide at SAFSR conference.
Restaurant Management 2 (6), 43
Jones, S.L., Carr, T.L. and McKeith, F.K. (1987) Palatability and
Storage Characteristics of Precooked Pork Roasts. J. of Food Sci.
52 (2), 279-281, 285
Jonsson, L. and Danielsson, K. (1981) Vitamin retention in foods
handled in foodservice systems. Leben.smitt.-Wissensch. Technol.
14, 94-96
Kahn, L.N. and Livingston, G.E. (1970) Effect of heating methods on
thiamine retention in fresh or frozen prepared foods. J. Food Sci.
35, 349-351
Kalinowski, T. (1988) Ready, set, serve. Can. Hotel Restaurant 66
(6), 24-26
Khan, M.A., Klein, B.P. and Lee, F.V. (1982) Thiamin content of
freshly prepared and leftover Italian spaghetti served in a uni-
versity cafeteria food service. J. Food Sci. 47, 2093-2094
Kossovitsas, C., Navar, M., Chang, C.M. and Livingston, G.E.
(1973) A comparison of chilled-holding versus frozen storage on
quality and wholesomeness of some prepared foods. J. Food Sci.
38, 901-902
Kraxner, U. (1981) Qualitiit und Verhalten einiger Gemiisearten nach
Lagerung in unterscheidlicher relativer Luftfeuchte. Doctoral
Thesis, Technical University, Munich, 141 pp.
Leadhetter, S. (1989) Sous-vide - a Technology Guide British Food
Manufacturing Industries Research Association, Leatherhead,
UK, 22 pp.
Levine, J.B. and Rossant, J. (1987) ‘Sous-vide’ cooking: haute cuisine
in a pouch? Business Week 13 July, pp. 104-105
Levy, P. (1986) A taste of technology. Observer Magazine 2 March,
58-60
Light, N. and Walker, A. (1990) Cook-Chill Catering: Technology
and Management Elsevier Applied Science, London, pp. 157-178
Light, N., Hudson, P., Williams, R., Barrett, J. and Schatheitle, J.M.
(1988) A pilot study on the use of sous-vide vacuum cooking as a
production system for high quality foods in catering. Int. J.
Hospitality Management 7 (1). 21-27
Food Control 1995 Volume 6 Number 1 51
Quality of ‘sous vide’ foods: P.G. Creed
Lumley, I.D. (1993) Vitamin analysis in foods. In: The Technology of
Vitamins in Food (Ed. P. Berry Ottaway) Blackie Academic &
Professional, Glasgow, pp. 172-232
McCuckian, A.T. (1969) The A.G.S. food system - chilled pasteur-
ised food. Cornell Hotel Restaurant Admin. Q. May, pp. 87-92,
99
Manser, S. (1988a) Comparing notes. Taste November, p. 16
Manser, S. (1988b) The perfect vacuum. T&e November, pp. 35-36
Mason, LX, Church, I.J., Ledward, D.A. and Parsons, A.L. (1990)
Review: The sensory quality of foods produced by conventional
and enhanced cook-chill methods. Int. J. Food Sci. Technol. 25.
247-259
Mecredy, J.M., Sonnemann, J.C. and Lehmann, S.J. (1974) Sensory
profiling of beer by a modified QDA method. Food technol. 28
(ll), 36-37,40-41
Mielgaard, M.C., Dalglelsh, C.E. and Clapperton, J.F. (1979) Beer
flavour terminology. J. Inst. Brewing 85, 38-52
Nandhasrl, P. and Suksangpleng, S. (1986) Application of high
performance liquid chromatography to determination of seven
water-soluble vitamins in white sauce. J. Sci. Sot. Thailand 12,
111-118
Napleton, L. (1991) Food packaging - frozen/chilled beats ambient.
Frozen Chilled Foods August, p. 3
Nicholanco, S. and Matthews, M.E. (1978) Quality of beef stew in a
hospital chill food-service system. J. Am. Dietetic Assoc. 72,
31-37
Petit, R. (1990) Clean - sous vide. Restaurant Hospital. 74, (ll), 150
Plggott, J.R. (Ed.). (1988) Sensory Analysis of Foods 2nd Edn,
Elsevier Applied Science, London
Polesello, A. and Rizzolo, A. (1986) Applications of HPLC to the
determination of water-soluble vitamins in foods (a review 1981-
1985). J. Micronutr. Anal. 2, 153-187
Paulsen, K.J. (1978) Vacuum-packaged cooked potatoes. In: How
Ready are Ready-to-serve Foods? (Ed. K. Paulus) S. Karger,
Base]. pp. 138-146
Powers, J.J. (1988) Current practices and application of descriptive
methods. In: Sensory Analysis of Foods (Ed. J.R. Piggott)
Elsevier Applied Science, London, pp. 187-266
Ring, A. (1986) Sous-vide: boon or threat? Caterer Hotelkeeper 24
July, p. 19
Raffael, M. (1984) Revolution in the kitchen. Caterer Hotelkeeper 16
August, pp. 34-35
Richmond, M. (Ed.) (1990) The Microbiological Safety of Food Part I
Report of the Committee on the Microbiological Safety of Food,
HMSO, London, pp. 60,68,74-76, 87,93,95
Robson, C.P. and CoUl.um, R. (1989) Pre-cooked chilled foods.
Cutering Health 1, 151-163
Rutledge, K.P. and Hudson, J.M. (1990) Sensory evaluation: method
for establishing and training a descriptive flavor analysis panel.
Food Technol. 44 (12), 78-84
Rutledge, K.P. (1992) Accelerated training of sensory descriptive
flavour analysis panelists. Food Technol. 46 (ll), 114-118
Saxby, M. J. (1978) Applications of high-performance liquid chroma-
tography in food analysis. In: Developments in Food Analysis
Techniques - I (Ed. R.D. King) Applied Science, London,
pp. 125-153
Scarpa, J. (1988) Sous vide - fresh technology. Restaurant Business
87 (4), 1 March, pp. 136, 138, 140
Schafheitle, J.M. and Light, N.D. (1989a) Technical note: sous-vide
preparation and chilled storage of chicken ballotine. Int. J. Food
Sci. Technol. 24, l-205
,SchaIheiBe, J.M. and Light, N.D. (1989b) Sous-vide cooking and its
application to cook-chill-what does the future hold? 1. Contemp.
Hospitality Management 1, 5-10
Schatheitle, J.M., Wll, R., Barrett, J., Hudson, P. and Light, N.
(1986) Sous-vide: the way ahead? In: The Future of Cook-chill
Technology in Catering (Ed. N. Light), Workshop at Dorset
Institute of Higher Education, (now Boumemouth University),
Poole, Dorset, UK, 17-18 April
Sellers, J. (1990) In the bag. Foodservice Equipment Suppliers
Specialist 43 (3). 44, 46, 48
Sessions, P. (1987) Sensible sous vide. Hospital Caterer May/June,
p. 14
Shamaila, M., Powrl, W.D. and Skura, B.J. (1992) Sensory evalua-
tion of strawberry fruit stored under modified atmosphere pack-
aging (MAP) by quantitative descriptive analysis. J. Food Sci. 57
(5), 1168-1172, 1184
Sh-zraman, K., Chuaqui-Offermanns, N., Lucht, L., McDnugall,
T. and Borsa. J. (1992) Microbioloeical and other characteristics
of chicken b&as; meat following electron-beam and sous vide
treatments. J. Food Prot. 55 (7), 528-533
Sheard, M. and Church, I. (1992) Sous Vide Cook-Chill Leisure and
Consumer Studies, Leeds Polytechnic, Leeds, UK, 47 pp.
Shortreed, G.W., Rickard, M.L., Swan, J.S. and Burtles, S.M.
(1979) The flavour terminology of Scotch whiskey. Brewer’s
Guardian 11,55-62
Smith, D.M. and Alvarez, V.B. (1988) Stability of vacuum cook-in-
bag turkey breast rolls during refrigerated storage. J. Food Sci. 53
(I), 46-48, 61
Smith, D.B. and Fullum-Bouchard, L. (1990) Comparative nutrition-
al, sensory and microbiological quality of a cooked chicken menu
item produced and stored by cook/chill, cook/freeze and sous vide
cook/chill methods. Poster presented at Canadian Dietetic Asso-
ciation Annual Conference, 7 June, 6 pp.
Sornay, M. (1990) The ‘sous vide’ system in catering. In: Chilled
Foods - the Ongoing Debate (Eds. T.R. Gormley and P. Zeuth-
en) Elsevier Applied Science, London, pp. 99-100
Stacey, C. (1985) Hilton pioneers. Caterer Hotelkeeper 7 November,
pp. 67, 70
Stites, C.R., McKeith, F.K., Bechtel, P.J. and Carr, T.R. (1989)
Palatability and storage characteristics of precooked beef roasts.
J. Food Sci. 54 (l), 3-6
Stone, IL, Side], J., Oliver, S., Waolsey, A. and Singleton, R.C.
(1974) Sensory evaluation by quantitative descriptive analysis.
Food Technol. 28 (ll), 24, 26, 28, 29, 32, 34
Stone, H. and Side], J.L. (1985) Sensory Evaluation Practices
Academic Press, Orlando
Thomson, D.M.H. (Ed.) (1988) Food Acceptability Elsevier Applied
Science, London
Tuan, S., Wyatt, J. and Anglemier, A.F. (1987) The effect of
erythorbic acid on the determination of ascorbic acid levels in
selected foods by HPLC and spectrophotometry. J. Micronutr.
Anal. 3, 211-228
Turner, M., Mottlshaw, J., Zacharlas, R. and Bognar, A. (1984)
Sensory quality and nutritive value of meals prepared from fresh
and pre-processed components. In: Thermal Processing and Qual-
ity of Foods (Eds. P Zeuthen et al.) Elsevier, London, pp. 371-
402
U&e-Saucedo, S.M. and Ryley, J. (1982) A comparative study of
ascorbic acid and thiamine retention in pouch sterilization and
canning. Proc. Inst. Food Sci. Technol. 15 (3), 120-128
Van Niekerk, P.J. (1988) Determination of vitamins. In: HPLC in
Food Analysb (Ed. E. Macrae) 2nd Edn, Academic Press,
London, pp. 133-184
Vedel, A., Charle, G., Chamey, P. and Tourmeau, J. (1972) B-l. Le
Vin - dt$nition B-2. Caracteres Organoleptiques Institut National
des Appellations d’origine des Vins et Eaux-de-vie, Macon,
France, cited by Powers, J.J. (1988)
Watler, B. (1988) L’incidence des nouveaux proc6dCs sur les teneurs
en vitamines des aliments. Inform. Di&&ique (3), 33-38
Watier, B. and Belliot, J.P. (1990) Aspect vitaminiques des produits
de la IV’ gamme et de la V’ gamme. Inform. DiUtique (l), 42-48
Watier, B. and BeUiot, J.P. (1991) Vitamines et technologie indus-
trielle rbcente. Cahiers Nutr. Di&&ique 26 (l), 23-26
Williams, A.A. (1975) The development of a vocabulary and profile
assessment method for evaluating flavour contribution of cider
and perry aroma constituents. J. Sci. Food Agric. 26,567-582
WlBiams, A.A. and Carter, C.S. (1977) A language and procedure
for the sensory assessment of Cox’s orange pippin apples. J. Sci.
Food Agric. 28, 1090-1104
Zacharlas, R. (1980) Chilled meals: sensory quality. In: Advances in
Catering Technology (Ed. G. Glew) Applied Science, London,
pp. 409-416
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