辐射肉品的特性及其质量控制研究

主要阐述了辐射技术对肉品微生物和肉品品质的影响,提出了对辐射肉品进行质量控制的措施,并对几种常用的肉品质量检测方法进行了阐述。     

Estimation of thermal diffusivity of foods using transfer functions

The effective thermal diffusivity of foodstuffs was estimated from time-temperature histories in the geometric center of samples exposed to heating and cooling processes.Transfer functions methodology was used as an alternative method to estimate the thermal diffusivity assuming that conduction was the main heat transfer mechanism. The samples were characterized as delayed first-order systems with unit gain, dead time (L) and time constant (τ).The results were compared with those obtained from the f_h value and with results reported in the literature.     

沛县鼋汁狗肉的制作

本文介绍了沛县鼋汁狗肉的制作工艺和相关信息.     

Assessment of the influence of diet on lamb meat oxidation

The effect of pasture- or concentrate-diet on colour stability, lipid oxidation and protein oxidation was measured in lamb meat (M. longissimus dorsi) during refrigerated storage of 7 days under gas permeable film. Lipid and protein oxidation increased rapidly with storage time while evolution of colour parameters exhibited a biphasic curve. Diet had an important effect on lipid oxidation where animals fed concentrate showed higher thiobarbituric reactive substance (TBARS) levels than animals fed pasture-diet. However the nature of diet did not affect protein oxidation or colour parameters of meat. In parallel anti-oxidant status of meat was estimated by measurement of vitamin E content and anti-oxidant enzyme activities while pro-oxidant status was evaluated by haeminic iron, polyunsaturated fatty acid (PUFAs) and glycogen content of muscle. Statistical analysis was performed in order to relate oxidation parameters to pro- and anti-oxidant status of muscle.     

Involvement of Clostridium gasigenes and C. algidicarnis in 'blown pack' spoilage of Brazilian vacuum-packed beef

The objectives of this study were to isolate psychrotrophic clostridia from Brazilian vacuum-packed beef cuts (spoiled or not) and to identify the isolates by using 16S rRNA gene sequencing. Anaerobic psychrotrophic microorganisms were also enumerated and samples were collected to verify the incidence of psychrotrophic clostridia in the abattoir environment. Vacuum-packed beef cuts (n = 8 grossly distended and n = 5 non-spoiled) and environmental samples were obtained from a beef packing plant located in the state of São Paulo, Brazil. Each sample was divided in three subsamples (exudate, beef surface and beef core) that were analyzed for vegetative forms, total spore-forming, and sulfide reducing spore-forming, both activated by alcohol and heat. Biochemical profiles of the isolates were obtained using API20A, with further identification using 16S rRNA gene sequencing. The growth temperature and the pH range were also assessed. Populations of psychrotrophic anaerobic vegetative microorganisms of up to 10¹⁰ CFU/(g, mL or 100 cm²) were found in ‘blown pack’ samples, while in non-spoiled samples populations of 10⁵ CFU/(g, CFU/mL or CFU/100cm²) was found. Overall, a higher population of total spores and sulfide reducing spores activated by heat in spoiled samples was found. Clostridium gasigenes (n = 10) and C. algidicarnis (n = 2) were identified using 16S rRNA gene sequencing. Among the ten C. gasigenes isolates, six were from spoiled samples (C1, C2 and C9), two were isolated from non-spoiled samples (C4 and C5) and two were isolated from the hide and the abattoir corridor/beef cut conveyor belt. C. algidicarnis was recovered from spoiled beef packs (C2). Although some samples (C3, C7, C10 and C14) presented signs of ‘blown pack’ spoilage, Clostridium was not recovered. C. algidicarnis (n = 1) and C. gasigenes (n = 9) isolates have shown a psychrotrophic behavior, grew in the range 6.2-8.2. This is the first report on the isolation of psychrotrophic Clostridium (C. gasigenes and C. algidicarnis) in Brazil. This study shows that psychrotrophic Clostridium may pose a risk for the stability of vacuum-packed beef produced in tropical countries during shelf-life and highlights the need of adopting control measures to reduce their incidence in abattoir and the occurrence of ‘blown pack’ spoilage.     

Effect of feeding growing–fattening rabbits a diet supplemented with whole white lupin (Lupinus albus cv. Amiga) seeds on fatty acid composition and indexes related to human health in hind leg meat and perirenal fat

A total of 20 weaned rabbits (33 days old) (10 per treatment) were fed one of two diets that included 150 g of sunflower meal (SF)/kg of diet or 120 g of whole white lupin (WL)/kg of diet for 42 days. The WL diet contained less saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) but more monounsaturated fatty acids (MUFA) than the SF diet. The WL diet significantly decreased SFA and PUFA content, as well as the PUFA n − 6/PUFA n − 3 ratio and saturation, atherogenic and thrombogenic indexes in hind leg meat. The fatty acid composition in perirenal fat was similar to that of hind leg meat; however, significantly higher MUFA levels were observed in rabbits fed the WL diet. Thus, feeding rabbits the WL diet affected the fatty acid profile of hind leg meat and perirenal fat in a favourable manner.     

Proteins in longissimus muscle of Korean native cattle and their relationship to meat quality

Proteomic profiling by two-dimensional gel electrophoresis and mass spectrometry of longissimus dorsi muscle tissue from Korean native cattle identified seven proteins that are differentially expressed in animals producing low and high quality grade beef. The expression level of alpha actin is increased in high quality grade beef and the expression levels of T-complex protein 1 (TCP-1), heat shock protein beta-1 (HSP27), and inositol 1,4,5-triphosphate receptor type1 (IP3R1), a new protein to be associated with meat quality, are increased in low quality grade beef. In particular, the quantitation of HSP27 and IP3R1 by both silver staining and immunoblotting correlated well with intramuscular fat content, meat tenderness, and free calcium levels. The data suggest that HSP27 and IP3R1 are potential meat quality biomarkers and their identification provides new insight into the molecular mechanisms and pathways associated with overall beef quality.     

当前食品香精研究开发的热点及展望

食品香精是加香产品的“灵魂”,是食品添加剂的重要组成部分。近年来我国食品香精呈现良好的发展势头,本文对当前食品香精研究开发的热点作了综述,并指出了未来的研究开发前景。     

Influence of the type of forage supplied to ewes in pre- and post-partum periods on the meat fatty acids of suckling lambs

The aim of this study was to evaluate the use of forage diets (grazing vs. hay) around the time of ewe parturition, on the fatty acids profile of suckling lamb meat (10-12 kg body weight). Forty-eight multiparous single-bearing ewes were used. The experimental treatments were conducted during the last 5 weeks of pregnancy and the 5 weeks of lactation in a 2 × 2 factorial design. Ewes were fed ad libitum on pastures or hay in the autumn. Results showed that milk from grazing ewes during the pre-partum period had a higher content of PUFA and CLA (P < 0.05) and VA, CLA in their suckling lambs' meat (P < 0.05). The effect in post-partum feeding was greater, revealing higher CLA, PUFA/SFA, PUFA n-3 and PUFA n-6/n-3 in milk and meat (P < 0.05). The CLA, VA and PUFA n-6/n-3 ratios are those that are most affected by grazing. Pre-partum grazing, regardless of post-partum feeding, improves FA composition, increasing CLA content in both milk and meat.     

Disparity of dietary effects on collagen characteristics and toughness between two beef muscles

Manipulation of growth rate and/or diet has been shown to affect protein turnover and may be used to improve beef quality. This trial was conducted to evaluate the effects of average daily gain (ADG) and diet on animal performance, collagen characteristics and beef quality of two different muscles; longissimus dorsi (LD) and semitendinosus (ST). Seventy six Hereford and Angus steers were assigned to three dietary management regimens for finishing: high grain diet based on corn (n = 28), alfalfa pasture (n = 22) and grass pasture (n = 26). Average daily gains were greater (P < 0.001) in Herefords vs. Angus and for corn- vs. pasture finished cattle. Overall, total collagen content was greater (P < 0.001) and the percentage of total collagen that was heat soluble was lower (P < 0.0001) for ST than for LD muscle. The lowest (P < 0.05) values for both total and heat soluble collagens were found in animals finished on corn. WBSF values for LD were greater (P < 0.01) in grass-fed vs. alfalfa- and grain-finished cattle while there was no difference in WBSF values for ST between grass- and corn-fed animals. No correlation between ADG and WBSF was observed for any muscle. ADG was not correlated with collagen solubility in ST, but was correlated (P < 0.05) with collagen solubility in LD. A key finding is that growth rate affected heat soluble collagen in the two muscles to a different extent. In conclusion, this study shows that different feeding strategies may not influence the tenderness of all muscles in a similar way.