A prospective study of food preferences in childhood

This study has evaluated the impact of food choices at 2–3 years old on food preferences later in life, by following up the same subjects. Early preferences were estimated through recordings of food choices conducted in a nursery canteen in children aged 2–3, from 1982 to 1999. The children were free to choose the composition of their lunch from among a varied offering of eight dishes. The same subjects (n=341) were contacted in 2001–2002 and so their ages varied from 17–22 (n=91), 13–16 (n=68), 8–12 (n=99) to 4–7 (n=83). Their present preference for the 80 foods most frequently presented at the nursery canteen was assessed through a questionnaire. Five food categories were studied: vegetables, animal products, cheeses, starchy foods and combined foods. The ranking of preference for the different food categories changed especially after puberty. However, regressions performed by food category indicated that for most categories, individual present preference was highly linked to individual preference at 2–3 years old. The link was the stronger for cheeses, followed to a lesser extent by animal products and vegetables. Present preferences increased with age for vegetables and they decreased with age for animal products only in females (to a lesser extent, they decreased with age for starchy foods and cheeses). Analyses by specific foods confirmed the global analysis. Individual present preference was linked to individual early preference for all mature cheeses and for 50% of the foods for other categories: most of these items were strongly flavoured. This study showed that preferences were stable from 2- to 3-year-old until young adulthood and that some changes in preference occurred during adolescence.     

广东部分地区食品中环己基氨基磺酸钠的含量调查

目的了解广东部分地区食品中环己基氨基磺酸钠添加情况。方法采用气相色谱法对458个随机在大型商场和小型超市售卖的包装食品进行环己基氨基磺酸钠含量的检测。结果本次测试共458个,14大类食品,其中19.2%食品添加了环己基氨基磺酸钠,且大部分食品中的添加量在GB 2760—2014《食品安全国家标准食品添加剂使用标准》内,属于可放心食用的食品,不过其中有2.8%的食品超出了标准范围。14大类中饮料类、腌渍的蔬菜、脱壳熟制坚果与籽类、熟制豆类、凉果类、冷冻饮品、果冻糕点、复合调味料、腐乳、带壳熟制坚果与籽类、饼干类食品的风险较低,方便食品(调味面制品)、蜜饯凉果食品的风险较高。结论食品监管部门仍需要继续保持在食品生产消费中对环己基磺胺酸钠的安全风险管理。     

Antimicrobial activity of foodborne Paenibacillus and Bacillus spp. against Clostridium botulinum

The saprophytic Paenibacillus and Bacillus spp. found in cooked chilled foods may have an effect on the growth of Clostridium botulinum, a major microbiological hazard, especially for pasteurized vacuum-packaged products. Culture supernatants of 200 strains of Paenibacillus and Bacillus strains isolated from commercial cooked chilled foods containing vegetables were screened for activity against C. botulinum type A, proteolytic type B, and type E strains in a well diffusion assay. Nineteen strains were positive against C. botulinum. Among those, seven Paenibacillus polymyxa strains showed the highest antibotulinal activity and the largest antimicrobial spectrum against C. botulinum strains. The antibotulinal activity was evaluated throughout the growth of a representative strain of the positive P. polymyxa strains. The antimicrobial activity was detected in the culture supernatant from late-log/early stationary phase of the bacteria, which occurred after 7 to 10 days of incubation at 10 degrees C and after 2 to 3 days at 20 degrees C in nutrient broth and in vegetable purées under aerobic or anaerobic conditions. In co-cultures with the positive strain of P. polymyxa in nutrient broth and vegetable purées, a C. botulinum type E strain was inhibited whenever P. polymyxa reached stationary phase and produced its antimicrobial activity before C. botulinum began its exponential growth phase. The antimicrobial activity of P. polymyxa against C. botulinum was attributed to the production of antimicrobial peptides resistant to high temperature and acidity. Other gram-positive and -negative bacteria (Escherichia coli, Streptococcus mutans, Leuconostoc mesenteroides, and Bacillus subtilis) were also sensitive to these antimicrobial peptides.     

Bacterial contamination of ready-to-eat foods and fresh products in retail shops and food factories.

Raw vegetables cut for salad, cooked salad, cooked rice, boiled noodles, bean curd, and cooked Japanese foods were purchased in 27 retail shops in Tokyo. Intact vegetables before being processed and ready-to-eat fresh salad products were obtained from two food factories located in the suburbs of Tokyo. Two hundred thirty-eight retail samples, 137 samples of intact vegetables, and 159 samples of fresh products were examined for aerobic plate count (APC), coliforms, Escherichia coli, Listeria spp., Staphylococcus aureus, and Bacillus cereus. The APC of retail foods were 2.1 to 5.7 log CFU/g, and the range for the coliforms was 0.1 to 2.3 log CFU/g. The APC and coliform values showed that the raw vegetables cut for salad were the most heavily contaminated among the six kinds of ready-to-eat foods examined. Although L. monocytogenes was not detected, two samples of raw vegetables and five kinds of cooked foods yielded Listeria spp. S. aureus was detected in one sample of Japanese cooked food. The APC of the intact vegetables were 2.9 to 7.3 log CFU/g upon arrival and 2.2 to 7.2 log CFU/g after 3 days storage at 10 degrees C. The APC of the fresh products were 3.4 to 7.6 log CFU/g upon arrival and 4.7 to 8.7 log CFU/g after 3 days storage at 10 degrees C. The isolation rates for coliforms were 6.1 to 50% for intact vegetables and 50 to 66.7% for fresh products. E. coli was detected only in the fresh products. B. cereus was isolated from 20.1% (17 of 81) of the intact vegetables and 9.2% (8 of 87) of the fresh products.     

Processing characteristics of beef roasts made from high and normal pH bull inside rounds

The processing characteristics of roasts manufactured from either high or normal pH bull inside rounds (semimembranosus and adductor muscles), which had been stored chilled or frozen, were investigated. Roasts were injected with a salt/phosphate brine and cooked to an internal temperature of 63 °C in a 70 °C water bath. High-pH meat that had been frozen had less purge than normal pH meat. However, pH did not affect purge from chilled meat. Meat pH and storage conditions did not affect retention of pumped brine. Cook yields were significantly (P<0.05) higher for roasts made from high pH meat (103.8 vs 98.8%). Raw and cooked meat colour was affected by meat pH but not storage condition. Cooking reduced the effect of pH on meat colour but cooked roasts manufactured from high pH meat were redder than roasts manufactured from normal pH meat.     

Calpains from thaw rigor muscle

Pre-rigor beef M. Longissimus lumborum and diaphragma were frozen at −70 °C and thawed at different temperatures and the activities of extracted calpains and the toughness of heated meat compared with those in chilled muscle.

Fresh muscle contained about 14 μg of μ-calpain/g and was unaffected by freezing, but was reduced after thawing. Rapid thawing at 30 °C for 20 min reduced the μ-calpain to 14%. When cooked from the frozen state, extensive shortening occurred and tender meat was obtained.

By storing at −3 °C for 1 day, thaw-shortening was prevented, but tougher meat obtained. The μ-calpain decreased to 70% whilst the m-calpain was unaffected. Toughness decreased after further storage at −3 °C, as did the μ-calpain. The latter changes were similar to those during development of rigor mortis and ageing of non-shortened meat stored at 4 °C. Variation in calpain activity, rather than in sarcomere length, are likely to be the cause of toughness variation in thaw rigor muscle.     

The effects of antifreeze proteins on chilled and frozen meat

The effects of cryoprotectant proteins, trivially termed ‘antifreeze proteins’, from the Antarctic Cod and the Winter Flounder were assessed in meat during chilling and freezing. In light-microscopy studies, bovine muscle (Sternomandibularis) samples were soaked in phosphate buffered saline with and without 0·1 mg/ml antifreeze protein. Samples were then held frozen (−20°C) or chilled (2°C) for 3 days. Samples were freeze-substituted, embedded in resin and sectioned. With antifreeze protein present, transverse sections of frozen samples had many small intracellular spaces, probably representing ice crystals. Frozen controls had much larger intracellular single spaces. Antifreeze protein had no effect on chilled samples.

Similarly treated samples were examined by scanning electron microscopy using a cryostage attachment. Chilled ovine muscle samples (Peroneus longus) were soaked for various periods (0–7 days) in 0·9% saline containing various concentrations of antifreeze proteins (0–1 mg/ml). Samples were then held frozen (−20°C) or chilled (2°C) for 5 or 7 days. With frozen samples, antifreeze proteins reduced the size of ice crystals, compared to the control. This effect depended upon the concentration used and the period of soaking before the samples were frozen, but was independent of source. Antifreeze proteins had no effect on chilled samples.     

Application of nonlinear regression analysis to the estimation of kinetic parameters for two enterotoxigenic strains ofBacillus cereus spores

Two enterotoxigenic Bacillus cereus strains, isolated from cooked chilled foods containing vegetables, were characterized in relation to safe food production by studying their heat resistance characteristics. The kinetic parameters of thermal resistance were determined by one-step nonlinear regression and were compared with those calculated by using two linear regressions. Results showed that the new analysis methodology applied in this study can improve the estimation ofD - and z - values. Great differences were found in the thermal resistance of the two strains. TheD_90°C were 4·04 and 39 min for the AV TZ415 and AV Z421 strains respectively. Growth studies indicated that the two strains were able to grow at refrigeration temperatures, but the minimum growth temperature for the AV Z421 strain was 10°C, while the less heat-resistant strain, AV TZ415, grew at 5°C.     

Comparison of the hydrophobic grid-membrane filter DNA probe method and the Health Protection Branch standard method for the detection of Listeria monocytogenes in foods

The standard Health Protection Branch (HPB) method for the detection of L. monocytogenes in foods involves lengthy enrichment, selection and biochemical testing, requiring up to 8 days to complete. A hydrophobic grid-membrane filter (HGMF) method employing a digoxigenin-labelled listeriolysin O probe required 5 days to complete, and included an image-analysis system for electronic data acquisition. A total of 200 food samples encompassing 8 high-risk food groups (soft and semi-soft cheeses, packaged raw vegetables, frozen cooked shrimp, ground poultry, ground pork, ground beef, jellied meats, and pâté) were screened for the presence of L. monocytogenes by the two methods. Overall, 32 (16%) and 30 (15%) of the naturally-contaminated food samples tested positive for L. monocytogenes by the HPB and DNA methods, respectively. The DNA probe method was highly specific in discriminating L. monocytogenes from other Listeria spp. present in 50 of the samples tested. Results showed 94% sensitivity and 100% specificity between the two methods. The HGMF DNA probe method is an efficient and reliable alternative to the HPB standard method for detecting L. monocytogenes in foods.     

Effect of cooling rate upon processing characteristics of pork meat of different glycolysis type during post mortem ageing

Rapid chilling was applied to porcine longissimus dorsi muscles at 1 h post mortem in order to observe its effect on the quality of canned products prepared from those of different pH₁ values.

The muscle from one side of each animal was removed from the carcase 50 minutes post mortem and divided into two longitudinal strips. One was chilled immediately to 13–15°C (1 h post mortem): the other after a further hour (2 h post mortem) acted as control. After the centre temperature had reached 10°C the muscles were stored in a refrigerator at 3–5°C.

Compared with the control samples (chilled at 2 h p.m.), rapid chilling from 1 h p.m. caused an improvement in the water-holding capacity and the texture of pork meat, which had higher pH₁ values and was processed at 2, 4 and 48 h p.m. There was minimum brine retention and texture score if samples—both rapidly chilled and control—were processed at 24 h p.m.

Although brine retention of PSE pork meat could not be increased even by rapid chilling, the texture of heat treated PSE pork showed an improvement during storage, which was more pronounced after ageing for 48 h, if PSE samples were chilled at 1 h p.m.     

SENSORY ATTRIBUTES AND NUTRIENT RETENTION IN SELECTED VEGETABLES PREPARED BY CONVENTIONAL AND MICROWAVE METHODS

Sensory characteristics and retention of vitamin C, vitamin B₆, calcium, and magnesium were determined in vegetables cooked by conventional and microwave methods. Fresh broccoli, cauliflower, and potatoes and frozen corn and peas were cooked by boiling, steaming, microwave boiling and microwave steaming to equivalent tenderness as measured by a shear press. The sensory analysis of the vegetables cooked by the four methods indicated that some differences existed in color, flavor, texture, and moistness of the vegetables. No one method resulted in vegetables with optimum sensory characteristics. The nutrient retention was highest in foods cooked by microwave steaming, followed by microwave boiling, followed by steaming, and then by boiling. Generally vegetables cooked by microwave techniques retained higher percentages of the U. S. Recommended Daily Allowances for the nutrients than those cooked by conventional methods.     

食品中李斯特菌污染状况研究

目的了解冷藏冷冻食品中李斯特菌污染状况。方法采用PCR方法对样品中的李斯特菌进行初筛,阳性样品用国标法确证,对6类冷藏冷冻食品共3586份样品进行了李斯特菌带菌状况调查。结果珠海地区李斯特菌污染较为普遍,且存在着多重污染现象,生鲜奶、生肉禽类、蔬菜类样品不仅带李斯特菌率高,且带单增李斯特菌率高。结论应加强冷冻食品的李斯特菌监测与管理。     

Ascorbic Acid and 5-Methyltetrahyclrofolate Losses in Vegetables with Cook/Chill or Cook/Hot-Hold Foodservice Systems

The percent retention of vitamin C and 5-methyltetrahydrofolate in seven cooked vegetables was analyzed using HPLC and compared in simulated cook/chill vs cook/hot-hold hospital foodservices. Retention of vitamins after conduction and infra-red reheating was investigated. Vegetables reheated after one day of chilled storage had greater losses of both vitamins compared to those held at 72°C for 30 min, but better vitamin retention than vegetables held hot 2 hr. There was no significant difference in nutrient retention due to method of reheating. If warm-holding is restricted to < 90 min, vitamin retention in vegetables is likely to be higher in a cook/hot-hold foodservice than with a cook/chill system.     

舟山市2006-2008年食源性致病菌污染状况分析

目的了解舟山市市售食品中食源性致病菌污染状况及分布和高危食品种类。方法参照国家食源性疾病监测网工作手册进行。结果检测生畜肉、生禽肉、非定型包装熟肉制品、动物性水产品、蔬菜、海水鱼、淡水鱼、冷菜、鲜榨果汁等共511件,检出沙门氏菌3株,检出单核细胞增生李斯特菌5株,检出空肠弯曲菌3株,副溶血性弧菌68株。结论舟山市居民主要消费食品存在食源性致病菌污染,其中水产品和熟肉制品污染较重,应引起有关部门重视,并加强监督、检查力度,加大对食品卫生安全的宣传教育工作。     

The persistence of infectious adenovirus (type 35) in mussels (Mytilus edulis) and oysters (Ostrea edulis)

Microbiological analyses of fruits and vegetables produced by farms in Minnesota and Wisconsin were conducted to determine the prevalence of Escherichia coli in pre-harvest fruits and vegetables. During the 2003 and 2004 harvest seasons, 14 organic (certified by accredited organic agencies), 30 semi-organic (used organic practices but not certified) and 19 conventional farms were sampled to analyze 2029 pre-harvest produce samples (473 organic, 911 semi-organic, 645 conventional). Before each harvest season, a farmer survey was conducted to collect relevant information on farm management practices that might affect the risk of E. coli contamination in fresh produce. The use of animal wastes for fertilization of produce plants increased the risk of E. coli contamination in organic (OR = 13.2, 95% CI = 2.2–61.2, P-value < 0.0001) and semi-organic (OR = 12.9, 95% CI = 2.9–56.3, P-value < 0.0001) produce significantly. Improper ageing of untreated animal manure significantly increased this risk in organic produce (OR = 4.2 95% CI = 1.7–12.3, P-value = 0.005) grown using such manure as a fertilizer. Organic growers who used cattle manure for fertilization of their crops showed significantly greater risk of contamination with the E. coli (OR = 7.4, 95% CI = 1.6–36.8, P-value = 0.003), compared to those who used other types of manure-based fertilizer. In Minnesota, organic and semi-organic produce collected from the southeastern (SE) part of the state were at a significantly greater risk of E. coli contamination (OR = 3.45, 95% CI = 1.8–35.2, P = 0.008), compared to those collected from farms located in the southern (S) regions of the state. In Wisconsin, organic and semi-organic produce collected from the southern (S) cluster of farms were at approximately 3-times greater risk of E. coli contamination (OR = 2.67, 95% CI = 1.3–9.4, P = 0.004), compared to those grown in the northern (N) cluster of farms.     

Effect of NaCl, polydextrose, and storage conditions on the functional characteristics and microbial quality of pre- and post-rigor salted beef

The functionality and microbial storage life of pre-rigor beef mince stored at −1.5 °C under vacuum or a saturated carbon dioxide atmosphere, or at −18 °C in polyethylene bags, was investigated. Salt (2% w/w) or salt plus the cryoprotectant Polydextrose^® (2%/2.6% w/w) was added pre-rigor to some samples. Chilled storage decreased salt soluble protein (SSP) by 13–18% (P < 0.01); frozen storage decreased SSP content by 20%. Pre-rigor salted mince in saturated carbon dioxide packs had a satisfactory microbial quality after 12 weeks storage. The cook yield of finely comminuted sausage batters made from that mince and from fresh pre-rigor mince were similar, although batter stress and strain decreased with chilled storage. Adding Polydextrose^® to salted mince improved batter strain compared with the non-additive and salt-only samples and improved batter stress compared with the salt-only samples. The microbial storage life of chilled vacuumpacked unsalted mince was less than 6 weeks; pre-rigor salting increased its storage life.     

Preparation and validation of a growth model for Bacillus cereus: the effects of temperature, pH, sodium chloride and carbon dioxide

The growth responses of a vegetative inoculum of Bacillus cereus as influenced by varying conditions of temperature, pH value and sodium chloride concentration (% w/v) and carbon dioxide concentration (% v/v) were determined in laboratory medium. Growth curves in concentrations of NaCl in the range 0.5–10.5% (w/v), pH values in the range 4.5–7.0, CO₂ concentrations in the range 10–80% (v/v) and storage temperatures from 10 °C to 30 °C were fitted using the regime of Baranyi et al. (1993). A response surface model was prepared and predictions of doubling time, growth rate, lag time and time to 1000-fold increase could be obtained for any set of conditions within the matrix studied. This model is included in Food MicroModel Version 1. Predicted doubling times from the model were compared to observed doubling times in the literature and the model was found to give realistic estimates of doubling time for a range of foods including milk, meat and poultry and carbohydrate-based products.     

Variation in post-mortem rate of glycolyis does not necessarily affect drip loss of non-stimulated veal

In this study the effect of the rate of post mortem pH fall on the water-holding capacity of meat from moderately chilled veal carcasses was investigated. Also the relationship between muscle protein denaturation and drip loss of veal was examined. Three groups of 10 Friesian Holstein male veal calves each were selected on the basis of their pH in M. longissimus thoracis et lumborum (LTL) at 3 hr post mortem (pH₃): (1) fast pH-fall, pH₃ < 6.2; (2) intermediate pH-fall, 6.5 < pH₃ < 6.6; (3) slow pH-fall, pH₃ > 6.7. After 48 hr of chilling the LTL was excised from the carcass and sampled for determination of drip loss, filter paper wetness, sarcomere length, protein solubility and transmission value. Differences in pH₃ were not associated with differences in drip loss, filter paper wetness or differences in protein denaturation. It is suggested that at the relatively high veal carcass chilling rate the effect of rate of pH-fall on protein denaturation and thus on drip loss is negligible. Drip loss of veal was highly correlated with both solubility of sarcoplasmic (r = −0.67; p < 0.001) and total muscle protein (r = −0.54; p < 0.01) and with transmission values (r = 0.66; p < 0.001). These results indicate that protein denaturation measurements may be a good predictor for drip loss of veal.     

不同利用方式对几种根茎类蔬菜亚硝酸盐含量的影响

以山药、胡萝卜、莲藕为实验材料,研究不同贮藏条件、烹饪方法和熟菜保存方式下3种根茎类蔬菜中亚硝酸盐含量的变化。结果表明：无论常温还是低温贮藏,贮藏7d内,3种根茎类蔬菜的亚硝酸盐含量均呈现先增加后降低的趋势,虽然常温贮藏的亚硝酸盐含量高于低温贮藏,但两者均小于4mg/kg。不同烹饪加工可显著降低3种蔬菜的亚硝酸盐含量,煮制、炒制、烤制加工方式的亚硝酸盐含量降幅分别为70%～83%、66%～80%和33%～55%,其中胡萝卜的亚硝酸含量降幅最大,莲藕的最小。低温和常温保存的熟菜,菜体中亚硝酸盐含量随时间延长而增加,保存到48h时,3种菜体的亚硝酸盐含量均小于4mg/kg,且低温远低于常温(前者最大为1.03mg/kg,后者最大为1.98mg/kg),参照食用的亚硝酸盐标准,低温(4℃)和常温(20℃)保存的熟制根茎类蔬菜食用安全期均达48h,且煮制和炒制加工的熟菜优于烤制。     

Detection of Aspergillus carbonarius and other black aspergilli from grapes by DNA OLISA™ microarray

Black aspergilli, and particularly Aspergillus carbonarius, are responsible for ochratoxin A production in grapes. Correct identification of these species is essential for toxicological risk assessment in grape and wine. A low-complexity oligonucleotide microarray (OLISA™, Apibio, F) based on DNA oligonucleotides probes, obtained from sequences of the calmodulin gene, was set up in order to detect A. carbonarius, A. japonicus/A. aculeatus and A. ibericus isolated from grape. The designed microarray distinguished all Aspergillus species and the detection limit for A. carbonarius was 3.2 pg of DNA as a template for the PCR reaction. This microarray offers a quick and parallel analysis to detect individual Aspergillus species in pure cultures and in naturally contaminated grape samples.