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At least 19 recordsLinked to original sources
PubMed1998

Glycaemic and insulinaemic responses to natural foods, frozen foods and their laboratory equivalents.

Glycaemic response to a food is determined by a large number of factors, of which composition is only one. The present study was designed to study the effect of composition and overnight refrigeration on the glycaemic response. The study involved determination of the glycaemic and insulinaemic response of healthy human volunteers to rice or potato, and to meals equivalent to these foods in terms of carbohydrate, protein, fat and fibre content; but made up of cornflour, casein, corn oil and cellulose. Further, each of these meals was served either freshly cooked, or after overnight storage in a refrigerator and rewarming. The natural foods led to a higher postprandial glycaemia than their respective equivalents, and the freshly cooked foods led to a higher glycaemic response than the refrigerated and rewarmed forms of the corresponding foods. No such consistent differences were observed in case of the insulinaemic responses. The difference in the glycaemic response to foods and their laboratory equivalents may be due to the unique physical arrangement of nutrients within the food or due to specific chemical differences in terms of macro-or micro-nutrients, non-nutrients or anti-nutrients. The difference in the glycaemic response to freshly cooked and refrigerated foods may be due to the formation of resistant starch during cold storage.

Adult↗
PubMed1967

Coliform behavior in frozen foods. I. Rapid test for the recovery of Escherichia coli from frozen foods.

An assortment of 496 samples of frozen foods consisting of fish or marine products, variety types, and cream pie desserts were subjected to four parallel examinations for the recovery of Escherichia coli. The test procedures consisted of two low-temperature (35 C) and two high-temperature (44 C) presumptive tests, followed by an E C confirmatory test at 45.5 C. Of all the test methods examined, a single Lauryl Sulfate Tryptose (LST) presumptive test at 44 C gave best E. coli recovery (425). This recovery compared favorably with the lengthier Association of Official Analytical Chemists test with which only 420 E. coli cells were recovered. The LST (44 C) test saves much time, since it renders a follow-up 48-hr confirmatory test unnecessary. Moreover, since 96% of all the E. coli are recovered within 24 hr by LST (44 C), it is essentially a 24-hr test. The results of this study also confirmed earlier findings, in that it is possible to describe a specific coliform bacteriological test method by simple reproducible productivity ratios. E. coli recovery dilution data and coliform group behavior were also examined.

Escherichia coli↗
PubMed1989

[The hygiene of refrigerated and frozen foods].

Health and spoilage hazards arising from refrigerated and deep frozen foods may be due to - raw materials, e.g. pathogenic microorganisms which come from infected living animals or contaminate raw foods during handling. Psychrotrophic organisms have particular significance as pathogens or spoilage organisms as they can multiply also during refrigeration; - improper processing. Temperature abuse and incorrect time/temperature relations are main causes for microorganisms being not destroyed at the expected rate or even getting a chance of multiplying. Proper handling after refrigeration or frozen storage of foods ("hygiene of thawing") deserves also particular attention. - contamination, i.e. initial contamination of raw products which are ready for consumption without further processing (fruits, raw salads). Recontamination which follows a heat process is much more important and occurs before, during and after application of cold. In those cases, again, one has to distinguish between products which (a) are ready for consumption without a process (bakery and confectionary goods, ice cream, drinking milk) and (b) have to pass a process which reduces the bacterial load before consuming the food (ready to eat dishes or other foods ready for reheating in the home). Sites of increased hygienic hazard are a) lack of partitioning "clean" and "unclean" areas and processes, b) defects of sanitation and hygiene of personnel, c) defects of packaging, d) leakage during aseptic filling. Hazards are controlled through product and plant specific analysis of the process flow followed by continuous monitoring the "Critical Control Points". As an example, a report is given on a study on random samples taken from 180.000 prepackaged deep frozen menus which had been produced for a mass meeting. Microbiological monitoring of the process revealed time/temperature relations as critical control points of primary importance. Particular problems arose from any stoppage at the production line. Reliable means to assure food safety and protect consumer's health are HACCP concept based in plant control programs rather than sporadic microbiological monitoring of end products.

Animals↗
PubMed1990

The occurrence of carpal tunnel syndrome in frozen food factory employees.

Two hundred and seven (207) active workers from two frozen food plants were classified according to their daily tasks and placed into three groups. Each classification was evaluated for risk factors which could lead to Carpal Tunnel Syndrome (CTS). The workers were thoroughly studied by structured interviews, neurological screening, and electrophysiological studies. Those workers who experienced little hands' local exposure to cold and low repetitive movements of the wrist (group I) served as the internal standard. In groups II (no local exposure to cold, but a high degree of repetitiveness) and III (a combination of local exposure to cold and a high degree of repetitiveness) 40.54% and 37.19%, of the workers respectively were diagnosed to have CTS by neurological studies. The risk of CTS for group II + III was 14.39 times higher than that of group I, when group I was compared with group II + III (high repetitiveness). After adjusted for sex, age, and/or the length of employment, group III still had a higher risk of CTS than group II. Repetitiveness as well as hands' local exposure to cold were found to be contributing factors in leading to CTS. Recognition, evaluation, and management of CTS in the related industries in Taiwan should be initiated to assure early diagnosis and prevention of this occupationally related syndrome.

Adult↗
PubMed1991

DSC studies and stability of frozen foods.

This paper discusses the role played by the "WLF decrease in viscosity" above the temperature of the glass transition (Tg) in the temperature dependence of the stability of frozen foods. In the first part, the complex features observed before the melting endotherm on DSC/DTA thermograms of sugar-water solutions are examined; they are suggested to be representative of a glass transition associated with enthalpy relaxation. In the second part, the values of Tg for some complex foods are discussed. It is shown that ice melting adds an important contribution to the WLF effect on the decrease of the viscosity of the freeze-concentrated phase. The temperature dependence of the deterioration processes observed in frozen food products is generally smaller than that expected from this viscosity decrease. Several hypotheses are presented to account for the discrepancy.

Calorimetry, Differential Scanning↗
PubMed2001

Survival of Escherichia coli O157:H7 in frozen foods: impact of the cold shock response.

The survival of Escherichia coli O157:H7 strains in both frozen foods and trypticase soy broth (TSB) was investigated following cold shocking at 10 degrees C for 1.5 h. Using both trypticase soy agar (TSA) and violet red bile agar (VRBA) as recovery media, it was demonstrated that survival levels between cold shocked (CS) and non-cold shocked (NS) E. coli in ground beef or pork were not significantly different (P < or = 0.05). In contrast, cold shocking E. coli in either milk, whole egg or sausage resulted in a significant(P < or = 0.05) enhancement in survival. For milk, survival levels of CS E. coli, by 28 days of frozen storage, were 1.89 and 1.66 log10 cfu/ml higher on TSA and VRBA, respectively, when compared to NS cells. In egg these values were 0.64 and 1.31, while in sausage, values of 0.74 and 1.19 were obtained. In TSB (pH 7) survival of CS E. coli for some strains was about 3 log10 cfu/ml higher when compared to NS cells. Acidification of TSB (pH 5), however, appeared to negate the protective effects of the cold shock treatment. In milk, increasing the differential between the growth and cold shock temperatures resulted in higher numbers of survivors. In this regard the growth-cold shock temperature protocol giving optimum protection was 37-10 degrees C. In contrast, growth of E. coli at 20 degrees C followed by cold shocking at 10 degrees C did not result in any significant freeze protection. In addition, increased protection due to cold shocking was correlated with the appearance of a novel protein appearing at pI 4.8 following isoelectric focusing analysis, thus demonstrating an alteration of protein synthesis.

Animals↗
PubMed1984

A new direct plate method for the enumeration of Escherichia coli in frozen foods.

A new method has been devised, incorporating a resuscitant stage, which allows direct isolation of Escherichia coli biotype I, Irregular type II and Irregular type VI. Rapid indole tests on the distinctive colonies produced enable determinations of E. coli biotype I to be made within 24 h. This method employs materials of low cost and achieves complete recovery of injured cells. It also detects not only anaerogenic strains but those which are slow in producing acid from lactose or give negative results by other methods. If required, further study of isolates can be made after the indole test. Comparisons were made between conventional methods, the new method and a similar direct plate method. The implications of the higher counts obtained by the two latter methods are discussed in relation to microbiological specifications and standards for frozen foods.

Bacteriological Techniques↗
PubMed1996

[Frozen food].

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Aged↗
PubMed1993

Methods for the separation of yeast cells from the surfaces of processed, frozen foods.

More aggressive pre-isolation treatments of samples, such as vigorous shaking, jet-streaming with excess of water and sonication, were applied in sequence to the study of yeast ecology of the surface of several frozen foods. The conventional isolation method based on bland shaking was unable to disengage yeast cells from their substrates in most of the cases, while each more aggressive treatment caused progressive separation of colony-forming units (cfu) along the sequence of application of the three procedures. Altogether, in the majority of cases, a few colony forming units were found on the surface of frozen fish, poultry, vegetables and mushrooms. Conversely, the numerically poor yeast flora is almost constantly represented by many species, always different from those found on the surface of the same foods in nature before processing. The uniformity of the composition of the yeast flora throughout the four different categories of foods excludes any possible occasional origin of the yeast colonization and probably indicates a processing plant origin.

Animals↗
PubMed1977

Some aspects of protein changes in frozen foods.

In the past decades many results on changes of food proteins caused by freezing and their relation to quality changes were found. Recently especially the nutrition physiological viewpoint of these alterations has aroused considerable interest. In the present paper the attempt is made to outline some aspects of these changes which are usually referred to as "denaturation" caused by freezing. After a description of the phenomena observed and their measurement, a survey of the main causes presumed for the "denaturation" of fish muscle proteins by freezing is given. With special consideration of the molecular range it can be said that generally aggregation phenomena prevail and that the participating molecules, or part of them, may still be native or more or less changed in their conformation before or during aggregation. Definite judgement of the nutritional properties of the altered proteins in frozen foods is possible only when convincing results of feeding experiments will be available.

Adenosine Triphosphatases↗