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Pressure- vs. heat-induced bacterial stress in cooked poultry sausages: a preliminary study.

Vacuum-packaged poultry cooked sausages were pressure-treated at 500 MPa by combinations of time (5-45 min) and temperature (2-80 degrees C) and later stored at 6-8 degrees C for 12 we. Mesophile and psychrotrophe counts were determined 1 d, 3, 6, 9 and 12 we after treatment and compared with those of cooked sausages pasteurized at 80-85 degrees C for 40 min. Both pressure and heat treatments offer great possibilities for preservation. Sausages pressurized at 65 degrees C for 15 min showed mesophile numbers below 2 log cfu g(-1) throughout the chill storage. Pressurization, unlike heat treatment, causes a reversible bacterial stress. Thus, injured cells recovered during storage and, at 6 and 12 we, after a temperature abuse (room temperature for approx. 24 h), counts increased up to 6.5 - 7.5 log units. Psychrotrophes were more sensitive to both treatments; no growth was detected the day after (a lethality of more than 4 log units).

Colony Count, Microbial↗

Microbial interaction in cooked cured meat products under vacuum or modified atmosphere at 4 degrees C.

AIMS: To investigate the antagonistic activity of two lactic acid strains against the spoilage microflora in cooked cured meat products, vacuum or modified atmosphere packed at 4 degrees C and to determine the inhibitory capacity of their bacteriocins. METHODS AND RESULTS: Frankfurter-type sausages and sliced cooked cured pork shoulder were inoculated with Leuconostoc mesenteroides L124 and Lactobacillus curvatus L442 or with their bacteriocins. The microbial, physico-chemical (pH, L- and D-lactate, acetate and ammonia) and colour changes were studied. Results under vacuum packaging showed that in the uninoculated samples of the pork product the spoilage microflora grew but in the inoculated ones the spoilage microorganisms (e.g. Brochothrix thermosphacta and enterococci) reduced during the storage. This observation was more pronounced in the samples with the addition of bacteriocins. In the frankfurter-type sausages the spoilage microflora did not grow in the uninoculated and inoculated samples. In the modified atmosphere enriched in CO2 the population of spoilage microflora remained at low levels in both products, indicating that CO2 has an effect on the spoilage microorganisms' growth. In the pork product the concentrations of acetate and d-lactate increased while L-lactate decreased, but in the frankfurter-type sausages increase of acetate and D-lactate was not observed. CONCLUSIONS: Lactic acid strains had an effect on the spoilage microflora growth but did not affect, negatively, the organoleptic properties of the products. These strains may be used as biopreservative cultures or their bacteriocins could be an important contribution to microbiological quality of meat products. SIGNIFICANCE AND IMPACT OF STUDY: Establishment of biopreservation as a method for extension of shelf life of meat products.

Animals↗

Taurine concentrations in animal feed ingredients; cooking influences taurine content.

The aim of this study was to determine the taurine content in a variety of animal feeds. There is very little information on the taurine content of ingredients used in home-prepared diets for dogs and cats, and foods fed to wild animals in captivity. This study reports the taurine content of both common and alternative feed ingredients, and compares taurine loss as a result of different methods of food preparation. Foods were selected based on their use in commercial and home-prepared diets. Animal muscle tissue, particularly marine, contained high taurine concentrations. Plant products contained either low or undetectable amounts of taurine. The amount of taurine that remained in a feed ingredient after cooking depended upon the method of food preparation. When an ingredient was constantly surrounded by water during the cooking process, such as in boiling or basting, more taurine was lost. Food preparation methods that minimized water loss, such as baking or frying, had higher rates of taurine retention.

Animal Feed↗

Gas cooking, respiratory health and white blood cell counts in children.

The use of gas stoves has been associated with respiratory symptoms of chronic airway inflammation and higher rates of respiratory infections. We used data from a 1992/93 survey of 2,198 East German school children (aged 5 to 14) to assess whether gas cooking increases respiratory symptoms and is associated with a chronic inflammatory process reflected by an increase in white blood cell (WBC) count in children who do not exhibit signs of an acute respiratory infection. We found increases for the respiratory symptoms 'cough without cold' [odds ratio (OR) = 1.68; 95% confidence interval (CI), 1.18-2.39], 'cough in the morning' (OR = 1.58; CI, 1.23-2.04) and 'cough during the day or at night' (OR = 1.42; CI, 1.13-1.78) in children living in homes with gas ranges, but lifetime prevalence of asthma, bronchitis, wheeze, and the prevalence of acute infections were not affected. Furthermore, we examined WBC levels in a subgroup of 1,134 children for whom blood samples were available and who did not suffer from an acute infection. We observed small increases in the risk of having WBC counts above the 75th or 90th percentile (8300 or 9800 cell counts per microliter) when children were exposed to gas cooking after adjustment for age, gender, and passive smoking (OR = 1.30; CI, 0.98-1.73, and OR = 1.38; CI, 0.91-2.10). The strongest effect estimates for chronic inflammation were found for those children likely to have been exposed at higher levels, that is when stoves had no fans, in smaller homes, and for children spending more time indoors.

Adolescent↗

Extrusion cooking of a high-fibre cereal product. 2. Effects on apparent absorption of zinc, iron, calcium, magnesium and phosphorus in humans.

1. The effect of extrusion cooking, using mild conditions, of a high-fibre cereal product on apparent small bowel absorption of zinc, iron, calcium, magnesium and phosphorus was studied. 2. Seven ileostomy subjects were studied during two periods (each of 4 d), on a constant low-fibre diet supplemented with either 54 g/d of a bran-gluten-starch mixture or the corresponding extruded product. 3. The apparent absorption of Zn, Mg and P was significantly decreased (P less than 0.05) during the period with extruded product compared with the period with bran-gluten-starch. No difference was found for Fe and Ca. 4. The negative effect of extrusion cooking of a product containing phytic acid on availability of Zn, Mg and P was small but could be of nutritional relevance in foodstuffs that are consumed frequently and in infant formulas.

Absorption↗

Influence of dietary vitamin E and oxidised sunflower oil on the storage stability of cooked chicken muscle.

1. The effects of oxidised dietary sunflower oil and dietary alpha-tocopheryl acetate supplementation on alpha-tocopherol concentrations in broiler muscle and on the storage stability of refrigerated, cooked, minced muscle were determined. Broiler chicks were fed on diets containing fresh sunflower oil and 30 (FS30) or 200 (FS200) mg alpha-tocopheryl acetate/kg, or oxidised sunflower oil and 0 (OS0), 30 (OS30) or 200 (OS200) mg alpha-tocopheryl acetate/kg. 2. Inclusion of oxidised sunflower oil significantly reduced dietary and hence, muscle alpha-tocopherol concentrations. 3. Oxidised oil increased oxidation in raw and cooked muscle, and reduced the oxidative stability of muscle during refrigerated and frozen storage. 4. Supplementation with alpha-tocopheryl acetate improved the stability of muscle, with stability increasing as muscle alpha-tocopherol concentrations increased, when fresh or oxidised oil was fed. Supplementation with 200 mg alpha-tocopheryl acetate/kg offset the effects of oxidised oil in breast, but not in thigh. 5. The results show that the prooxidising effects of oxidised oils in muscle foods can be overcome, but alpha-tocopherol content needs to be adequately adjusted to compensate for increased oxidative stress. Supplementation with 200 to 400 mg alpha-tocopheryl acetate/kg may be necessary to achieve an optimum muscle alpha-tocopherol concentration.

Animals↗

Stability of fusarin C: effects of the normal cooking procedure used in China and pH.

Fusarin C (FC) is a naturally occurring mutagen found on Fusarium moniliforme-contaminated corn. In Linxian, China, an area of exceptionally high incidence of esophageal cancer, the milled corn is made into small cakes called wotou, which are steamed. It has been suggested that FC may play a role in the etiology of esophageal cancer, but this has been questioned, in part, because of the thermal instability of FC. We therefore measured the effects of temperature on FC stability, mimicking the cooking process. FC was extracted from the wotou and quantitated by both reverse-phase high-performance liquid chromatography and the Ames assay. After wotou were steamed for 30 minutes, 11% and 3% of the initial FC remained, as detected by the two assays, respectively. The milled corn, when moistened with water, had a pH of 6.1, which was lowered to 5.3 when it was inoculated with F. moniliforme and cultured for three weeks. Pickled vegetables are sometimes added to the wotou, which further reduces the pH. To determine the effects of pH on FC, it was heated in solution, with the pH varied between 4 and 8. Its stability was very pH dependent, decomposing more rapidly as the pH increased. Because ingested FC would also be subjected to the low pH of the stomach, it was treated for 30 minutes at 37 degrees C and pH values ranging from 1.0 to 7.0. FC was stable (less than 15% decomposition) under these conditions. If FC is a significant health threat, it could most easily be destroyed by cooking at slightly basic pH values.

China↗

Feeding of a well-cooked beef diet containing a high heterocyclic amine content enhances colon and stomach carcinogenesis in 1,2-dimethylhydrazine-treated rats.

Epidemiologic studies have linked the consumption of red meat and the consumption of highly browned meats containing high levels of heterocyclic aromatic amines (HCAs) to increased risk of colorectal cancer or polyps. The present study determined the effects of long-term feeding of beef-containing diets with low and high levels of HCAs (in the context of a low or high beef tallow diet) on a standard 1,2-dimethylhydrazine (DMH)-induced colon tumorigenesis protocol. Very lean beef was cooked by a variety of methods at different temperatures, and the levels of the major HCAs (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline, and 2-amino-1-methyl-6-phenylimidazo[4,5-f]pyridine) were measured by high-performance liquid chromatography. Diets incorporating beef containing low or high levels of HCAs were fed for 12 weeks, during which DMH was administered to induce colon tumors, followed by various dietary regimens as promotional stimuli. Feeding of a beef diet high in HCAs resulted in more DMH-induced colon adenocarcinomas, but only in the context of a low-fat diet. The high-HCA diets increased stomach tumors in all DMH-treated rats. An apparent interaction of high HCA with a high fat level reduced the colon tumor incidence and tumor numbers in those diets containing both factors. These results support the epidemiologic data linking well-cooked meat to increased risk for colon and stomach cancer, but the role of dietary fat level remains puzzling.

1,2-Dimethylhydrazine↗

Effect of cooking on availability and in vitro nitrosation of precursors of volatile N-nitroso compounds in seafood.

Aqueous extracts of uncooked and cooked samples of squid and shrimp, characterized by their high amine content, were exposed to nitrate. The samples were cooked following traditional Italian recipes: stewing, grilling and deep-frying for squid; boiling, grilling and deep-frying for shrimp. Incubation of the aqueous extracts with nitrite in acidic medium yielded appreciable amounts of N-nitrosodimethylamine. Ascorbic acid and alpha-tocopherol were effective in preventing nitrosation of seafood amines only in the presence of molar excesses of these vitamins. An attempt at modulating nitrosation through the use of food ingredients naturally rich in vitamin C was unsuccessful.

Animals↗

Lead contamination during domestic preparation and cooking of potatoes and leaching of bone-derived lead on roasting, marinading and boiling beef.

Lead concentrations were measured in boiled, mashed potatoes and in baked potatoes that had been prepared and cooked in domestic kitchens. Levels of lead in the boiled, mashed potatoes ranged from below the 1 microgram/kg limit of detection up to 18 micrograms/kg with a mean of 6 micrograms/kg (wet weight). In the large majority of cases the lead in the tap water was the predominant source of the metal. Higher amounts of lead (range 11 micrograms/kg to 56 micrograms/kg, mean 27 micrograms/kg) were present in baked potatoes and this was attributed to soil adhering to the potato skin. The extent of leaching of lead from bone during cooking has also been investigated. For beef stocks there was little evidence to suggest that significant migration of bone lead occurred. For beef casseroles, marinaded in red wine, some leaching did occur from beef joints containing elevated amounts of bone lead; however the levels were all below 350 micrograms/kg and, on average, less than double that found in casseroles prepared from normal joints where the bone lead levels were an order of magnitude less.

Animals↗

Compositional analysis of samples of thermoset polyester and migration of ethylbenzene and styrene from thermoset polyester into pork during cooking.

The levels of ethylbenzene, styrene, benzene and benzaldehyde in samples of thermoset polyester were determined by dynamic headspace/gas chromatography. Styrene was present at levels from 50 to 1400 mg kg-1, ethylbenzene up to 25 mg kg-1 and benzaldehyde up to 180 mg kg-1. Benzene levels were usually less than 1 mg kg-1, but one article contained 19 mg kg-1. Levels of styrene dimers and trimers were estimated using size exclusion chromatography followed by gas chromatographic (GC) analysis and were present at approximately 100 mg kg-1 and 700 mg kg-1 respectively. The principal identified constituents of solvent extracts were stearic and palmitic acids, present at a combined level of nearly 1% by weight of the plastic. Styrene was shown to be produced by thermal depolymerization at temperatures of 175 degrees C and above. The migration of ethylbenzene and styrene into belly pork cooked in thermoset polyester dishes for 1.5 h at 175 degrees C was measured by Likens-Nickerson extraction of the cooked meat and GC/MS analysis of the extracts. Migration ranged from 6 to 2400 micrograms kg-1 for styrene and from < 6 to 34 micrograms kg-1 for ethylbenzene.

Animals↗

Purity of food cooked in stainless steel utensils.

An extensive programme of cooking operations, using household recipes, has shown that, apart from aberrant values associated with new pans on first use, the contribution made by 19% Cr/9% Ni stainless steel cooking utensils to chromium and nickel in the diet is negligible. New pans, if first used with acid fruits, showed a greater pick-up of chromium and nickel, ranging from approximately 1/20 to 1/3 and 1/20 to 1/2 of the normal daily intake of chromium and nickel respectively. This situation did not recur in subsequent usage, even after the pan had been cleaned by abrasion. A higher rate of chromium and nickel release in new pans on first use was observed on products from four manufactures and appears to be related to surface finish, since treatment of the surface of a new pan was partly, and in the case of electropolishing, wholly effective in eliminating their initial high release.

Chromium↗

Cooking and Fe fortification have different effects on Fe bioavailability of bread and tortillas.

OBJECTIVE: To identify iron sources for wheat- (WF) and corn-flour (CF) fortification taking into account the effect of cooking. METHODS: Sixty-six Fe-depleted rats were replete with various Fe sources. Fe bioavailability and utilization in wheat bread (WB) and corn tortillas (CT) fortified with various Fe sources was assessed after the depletion and repletion periods. RESULTS: Baking decreased the phytates content of WF by 97%. Improvements in Hb and FeHb were greater in rats fed unfortified WB than in those fed unfortified WF. Fe fortification had no benefit. In contrast, phytates content was unchanged by tortilla preparation, but fortification improved iron availability. Iron bioavailability indicators were best in rats fed CT fortified with ferrous sulfate and NaFe(III)EDTA than in those fed unfortified CT or CT plus reduced Fe. CONCLUSION: We concluded that baking WF bread improved the bioavailability of native Fe with no further effect of fortification. Pan-cooking of lime-treated CF did not improve Fe bioavailability, but addition of Ferrous sulfate or NaFe(III)EDTA did it, despite the high phytate and calcium content of tortillas.

Anemia, Iron-Deficiency↗

Physico-chemical characteristics, water absorption, soaking and cooking properties of some Sicilian populations of chickpea (Cicer arietinum L.).

The physical and physico-chemical properties of several Kabuli chickpeas originating from Sicily (South Italy) were determined. Twelve genotypes in all, including two controls (ILC484, of the ICARDA genebank, and 'Calia', a traditional Italian cultivar), were analysed. A large variability among genotypes was ascertained for swelling capacity (coefficient of variation [CV] = 27.9%), swelling index (CV = 30.5%) and calcium content (CV = 39.3%). The lowest variability was observed for seed coat (CV = 8.6%) and seed weight (CV = 9.6%). Genotype statistically affected all traits, whose mean values were: seed weight, 0.340 +/- 0.03 g; seed coat, 4.47 +/- 0.38%; seed volume, 0.292 +/- 0.04 ml; seed density, 1.18 +/- 0.15 g/ml; hydration capacity, 0.361 +/- 0.09 g/seed; hydration index, 1.05 +/- 0.21; swelling capacity, 0.346 +/- 0.10 ml/seed; swelling index, 1.21 +/- 0.37; cooking texture, 2.61 +/- 0.38 kg/cm(2); and calcium, 109.6 +/- 43.11 mg/100 g dry weight. Correlation coefficients among characteristics were also estimated. The genotype '44M33' was found to be interesting having good seed weight and low seed coat incidence and calcium content, all important attributes affecting cooking quality.

Absorption↗

Calcium, iron and zinc uptakes by Caco-2 cells from white beans and effect of cooking.

White beans (Phaseolus vulgaris L.) have an interesting content of essential elements, calcium, iron and zinc, but they content also phytates, oxalates, proteins, polyyphenols and complex polysaccharides that are known to interact with minerals and to affect their bioavailability. The bioavailability of calcium, iron and zinc from raw and cooked white beans was estimated using their uptake by Caco-2 cells as the criteria. Previously, the mineral fraction (soluble or dialysable) to be added to the Caco-2 cell monolayer was selected. The results obtained show that cooking increases the Caco-2 cells' uptake percentages (calcium, 18.8 versus 3.6; iron, 33.7 versus 1.7; and zinc, 17.2 versus 2.1) and improved the value of beans as a dietetic source of minerals.

Biological Availability↗

The effect on intestinal transit and the feces of raw and cooked bran in different doses.

Ten healthy male subjects on a low fiber diet were given two doses of raw wheat bran (12 and 20 g/day) and two doses of cooked bran (13.2 and 22 g/day). Both doses of raw bran increased fecal dry weight but only the higher dose decreased transit time and increased stool volume. Individual stool size was increased only by raw bran 12g/day. Neither bran influenced fecal wet weight or stool frequency. This study suggests that the cereal manufacturing process alters wheat bran so that cooked bran has less effect on the intestine than does a comparable amount of raw bran.

Adult↗

Gas cooking and smoking habits and the risk of childhood and adolescent wheeze.

The authors investigated the risk of wheezing illnesses in relation to contemporaneous pollutant exposures (gas cooking, heating, and smoking) in childhood and adolescence in a cohort of 2,289 United Kingdom subjects. Data from two questionnaires assessing wheezing at ages 7-8 and 15-17 years and one questionnaire on current and past pollutant exposures at age 16-18 years were studied (1987-1996). The 1,868 subjects returning all three questionnaires were divided into three groups representing childhood (10.5%), adolescent (10.9%), and persistent (i.e., both; 16.3%) wheezing and compared with 1,165 controls (62.4%) without wheezing. The estimated risks of childhood wheezing were increased by exposure to any gas in childhood (odds ratio (OR) = 1.47, 95% confidence interval (CI): 1.05, 2.04) and exposure to a gas hob in childhood (OR = 1.56, 95% CI: 1.13, 2.16) and were increased further in those persistently exposed. Risk of persistent wheezing in adolescence was paradoxically reduced by exposure to a gas hob (OR = 0.67, 95% CI: 0.50, 0.91), possibly because of selection avoidance. Contemporaneous exposure to combined smoking by both parents was associated with wheezing in all groups (odds ratios ranged from 1.62 (95% CI: 1.06, 2.46) to 1.93 (95% CI: 1.10, 3.38)). Maternal smoking alone was associated with persistent wheezing and with both childhood (OR = 1.90, 95% CI: 1.06, 3.39) and persistent (OR = 2.18, 95% CI: 1.15, 4.14) wheezing if smoking occurred throughout childhood and adolescence. The authors conclude that exposures to gas cooking and smoking in childhood and adolescence increase the overall risk of wheezing.

Adolescent↗

Identification of urine metabolites of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine following consumption of a single cooked chicken meal in humans.

Many studies suggest that mutagenic/carcinogenic chemicals in the diet, like 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), may play a role in human cancer initiation. We have developed a method to quantify PhIP metabolites in human urine and have applied it to samples from female volunteers who had eaten a meal of cooked chicken. For this analysis, urine samples (5 ml) were spiked with a deuterium-labeled internal standard, adsorbed to a macroporous polymeric column and then eluted with methanol. After a solvent exchange to 0.01 M HCl, the urine extracts were passed through a filter, applied to a benzenesulfonic acid column, washed with methanol/acid and eluted with ammonium acetate and concentrated on a C(18) column. The metabolites were eluted from the C(18) column and quantified by LC/MS/MS. In our studies of human PhIP metabolism, eight volunteers were fed 200 g of cooked chicken containing a total of 27 microg PhIP. Urine samples were collected for 24 h after the meal, in 6 h aliquots. Although no metabolites could be found in urine collected from volunteers before eating the chicken, four major human PhIP metabolites, N:(2)-OH-PhIP-N:(2)-glucuronide, PhIP-N:(2)-glucuronide, 4'-PhIP-sulfate and N:(2)-OH-PhIP-N:3-glucuronide, were found in the urine after the chicken meal. The volunteers in the study excreted 4-53% of the ingested PhIP dose in the urine. The rate of metabolite excretion varied among the subjects, however, in all of the subjects the majority of the metabolites were excreted in the first 12 h. Very little metabolite was detected in the urine after 18 h. In humans, N:(2)-OH-PhIP-N:(2) glucuronide is the most abundant urinary metabolite, followed by PhIP-N:(2)-glucuronide. The variation seen in the total amount, excretion time and metabolite ratios with our method suggests that individual digestion, metabolism and/or other components of the diet may influence the absorption and amounts of metabolic products produced from PhIP.

Animals↗