Physical and Sensory Characteristics of Fresh Pork Leg Roasts Cooked at Low Temperatures

The effects of oven temperatures of 82, 93, 121 and 163°C were studied using 31 fresh pork leg roasts cooked to 74°C in oven bags. Warmed-over-flavor (WOF) was measured by sensory analysis after holding 3 hr at 68°C and after holding 24 hr at 2°C and then reheating to 68°C prior to serving. Roasts cooked at 82 and 93°C tended to have less WOF after refrigeration and reheating than roasts cooked at 121 and 163°C. Roasts cooked at 93°C had fewer aerobic mesophilic bacteria than those cooked at 121 and 163°C. In general, objective and sensory perception measurements indicated that roasts cooked at 82 and 93°C were of higher quality.     

The storage stability and textural, physico-chemical and sensory quality of low-fat ground pork patties with Carrageenan as fat replacer

Low‐fat ground pork patties (<10% total fat) made with carrageenan added at either 0.25, 0.50 or 0.75% final concentration were processed and the compositional and sensory characteristics compared with control patties which contained 20% fat. The moisture content of raw and cooked low‐fat patties was significantly (P < 0.05) higher than control patties because of greater amounts of water added during formulation. Cooking yield, fat and moisture retention also improved significantly (P < 0.05) in low‐fat patties that had carrageenan incorporated when compared to a control product. The dimensions of the low‐fat patties were maintained better than those of the control product during cooking. The sensory attributes of low‐fat patties with 0.5% carrageenan were similar to those of the high‐fat control. The lipid profile revealed as much as a 47.7 or 44.1% decrease in total lipids and cholesterol content respectively, compared with the controls. The calorie content was reduced by 31.1% in low‐fat cooked patties compared with the controls. The texture profile of low‐fat patties that had been made with 0.5% carrageenan were similar to control patties with only a slight increase in hardness and gumminess in the low‐fat product. The low‐fat ground pork patties made in the present study remained stable without any appreciable loss of physico‐chemical, microbiological and organoleptic quality during refrigerated storage (4 ± 1 °C) for 21 and 35 days in aerobic and vacuum packaging respectively.     

Species identification of meat products by ELISA

ELISA methods used in this study are proved to detect low contents of animal species (pork, beef, sheep and poultry), even in highly processed foods. They present the advantages of being robust, cheap and easy to perform. Nevertheless, F factors, determining the threshold values of the test, need to be validated for each species.     

Nonaccumulation of Residues in Swine Tissue Following Extended Consumption of Deoxynivalenol-Contaminated Diets

Several tissues from 62 pigs fed deoxynivalertol (DON)-contamirtated diets (6.0–7.6 mg DON/kg feed) for periods of 3–7 wk were analyzed to determine if residues accumulated following extended ingestion of the toxin. In the liver, kidney and backfat samples analyzed, trace levels were found, measuring on average 3.0 ± 3.5, 5.0 ± 9.2, and 6.7 ± 9.6 ng DON/g wet tissue, respectively. Only 13% (24/186) of samples had more than 10 ng/g, and of these only two contained more than 50 ng/g. These results indicate that when pigs are fed DON-contaminated grains, residues do not appear to accumulate in tissues to any appreciable extent.     

Lipid Oxidation in Cooked Pork as Affected by Vitamin E, Cooking and Storage Conditions

The individual and combined effects of muscle vitamin E level, cooking conditions (duration, temperature and rate) and packaging on lipid oxidation in refrigerated cooked pork were examined. Oxidative stability following cooking was higher in pork with a higher vitamin E level (p<0.01), cooked at a lower cooking temperature (p<0.01), cooked for a shorter time (p<0.01), cooked at a faster cooking rate (p<0.05) or stored in vacuum packs (p<0.01). Significant two-way and three-way interactions were observed between the effects of muscle vitamin E level, cooking conditions and packaging on lipid oxidation. Adopting more than one of these approaches to minimize lipid oxidation was more effective than adopting a single approach.     

猪肉背膘中3-甲基吲哚测定方法的研究

3-甲基吲哚即粪臭素，是小肠中未消化的蛋白质在大肠厌氧微生物作用下的产物之一，对未阉割的公猪肉品质有显著的负面影响。本次实验就对猪肉背膘中3-甲基吲哚的测定方法进行了研究。结果为：标样浓度在120ng／ml范围内线性良好，回收率在97％左右，样品相对偏差在3％以下。表明该方法的灵敏度和准确度均较好。     

Oxidative and color stability of cooked ground pork containing lotus leaf (Nelumbo nucifera) and barley leaf (Hordeum vulgare) powder during refrigerated storage

This study aimed to evaluate the oxidative and color stability of cooked ground pork containing lotus leaf powder at 0.1 (LP1) and 0.5% (LP2) as well as barley leaf powder at 0.1 (BP1) and 0.5% (BP2) during refrigerated storage for 10 days. The oxidative stability of these powders was compared with butylhydroxytoluene (BHT). LP1 had higher a* and lower b* values than the control (-) over 4 days (p<0.05). The pH values of the ground pork samples made with addition of LP and BHT decreased until day 4 and then increased. Thiobarbituric acid-reactive substance (TBARS) values were lowest in LP2 on day 10 (p<0.05). The ground pork samples containing LP and BP had lower peroxide values (POVs) and conjugated dienes (CD) compared to the control (-).These results indicate that LP or BP can be incorporated into ground pork to effectively retard oxidation after cooking.     

Production of biogenic amines by lactic acid bacteria and enterobacteria isolated from fresh pork sausages packaged in different atmospheres and kept under refrigeration

The occurrence of in vitro amino acid activity in bacterial strains associated with fresh pork sausages packaged in different atmospheres and kept in refrigeration was studied. The presence of biogenic amines in decarboxylase broth was confirmed by ion-exchange chromatography and by the presence of the corresponding decarboxylase genes by PCR. From the 93 lactic acid bacteria and 100 enterobacteria strains analysed, the decarboxylase medium underestimates the number of biogenic amine-producer strains. 28% of the lactic acid bacteria produced tyramine and presented the tdc gene. All the tyramine-producer strains were molecularly identified as Carnobacterium divergens. Differences on the relative abundance of C. divergens were observed among the different packaging atmospheres assayed. After 28 days of storage, the presence of argon seems to inhibit C. divergens growth, while packing under vacuum seems to favour it. Among enterobacteria, putrescine was the amine more frequently produced (87%), followed by cadaverine (85%); agmatine and tyramine were only produced by 13 and 1%, respectively, of the strains analysed. Packing under vacuum or in an atmosphere containing nitrogen seems to inhibit the growth of enterobacteria which produce simultaneously putrescine, cadaverine, and agmatine. Contrarily, over-wrapping or packing in an atmosphere containing argon seems to favour the growth of agmatine producer-enterobacteria. The production of putrescine and cadaverine was associated with the presence of the corresponding amino acid decarboxylase genes. The biogenic amine-producer strains were included in a wide range of enterobacterial species, including Kluyvera intermedia, Enterobacter aerogenes, Yersinia kristensenii, Serratia grimesii, Serratia ficaria, Yersinia rodhei, Providencia vermicola and Obesumbacterium proteus.     

Sodium Lactate/Sodium Chloride Effects on Aerobic Plate Counts and Color of Aerobically Packaged Ground Pork

Ground pork (15% fat) was formulated to contain 0% to 3.0% sodium chloride and/or 0% to 3.0% sodium lactate (SL) resulting in 28 treatment combinations. Five replications consisted of two with low initial microbial loads (< 10³ CFU/g) and three with high initial loads (> 10⁵ CFU/ g). Ground pork (454g) was overwrapped in PVC and stored (4°C) aerobically for 21 d. A significant salt × SL interaction existed for redness of samples with low initial aerobic plate count (APC). Red color was best preserved by 2.0% or 3.0% SL. Initial pH values of low and high initial APC samples were similar. Initial product pH was best maintained by higher SL levels in low initial load samples and by higher sodium chloride levels in high initial load samples. Samples containing 3.0% SL had the lowest APC regardless of salt level.