不同生姜提取物的急性毒性研究

观察不同生姜提取物的急性毒性并对其进行评价.依据GB15193-2003(食品安全性毒理学评价程序和方法>进行急性毒性试验,研究生姜食品的急性毒性.生姜水提物和生姜醇提物对两种性别的小鼠经口毒性灌胃达66.67g/kg两周内动物未见明显中毒症状,无动物死亡.取灌胃1 d后与灌胃前的体重差值及灌胃一周后及灌胃前的体重差值做为小鼠长势的数据描述进行分析.经口急性毒性作用试验表明生姜无毒级物质.结论:生姜具有较好的食用安全性.     

超声波处理对淘汰蛋鸡嫩化效果的初步研究

采用超声波对淘汰蛋鸡肉的嫩化效果进行了初步的研究，对超声波的频率，功率，处理时间及处理媒质CaCl2的不同浓度进行了测试对比，结果表明：超声波与CaCl2相结合对淘汰蛋鸡肉的嫩化效果明显，超声渡的最佳频率为26．4kHz，功率为400W，处理时间15min，处理媒质CaCl2浓度为250mmol／L。     

MECHANICAL MEASUREMENTS OF MEAT TENDERNESS USING THE NIP TENDEROMETER

Abstract. A series of evaluations to compare the sensory panel ratings for tenderness with the Warner-Bratzler shear force and the Nip Tenderometer values was conducted using 150 pork chops, 239 lamb chops and 674 beef steaks. The Warner-Bratzler shear force values were more highly correlated with panel tenderness ratings than were the Nip Tenderometer readings for samples of pork, lamb and beef tested after cooling to room temperature (23 °C). Nip Tenderometer determinations on hot samples of beef (75 °C) were more closely related to panel tenderness ratings ( r =— 0.80) than were Nip Tenderometer readings ( r =— 0.58) or shear force values ( r =— 0.63) obtained on cold samples (23 °C). The combined advantages of ease and speed of application, correlation with sensory panel ratings and the demonstrated accuracy in identifying 'tough' vs 'tender' steaks suggest that the Nip Tenderometer has potential as an objective means for evaluating meat tenderness.     

APPLICATION OF ACTINIDIN FROM KIWIFRUIT TO MEAT TENDERIZATION AND CHARACTERIZATION OF BEEF MUSCLE PROTEIN HYDROLYSIS

The effect of actinidin on the tenderness of broiled bovine semitendinosus (ST) steaks was studied. An actinidin activity of 400 U/mL resulted in Kramer shear values and sensory tenderness scores equivalent to that produced by Adolph's papain-based meat tenderizer (18 U/mL). Both were significantly (P<0.05) more tender than steaks having no tenderizing treatment. Actinidin did not over-tenderize the steak surface as did Adolph's meat tenderizer. Hydrolysis of myofibrillar proteins in enzyme-treated steaks prior to broiling was considerably less for actinidin than for papain when using activities to attain equal Kramer shear values of broiled steaks.     

MEAT TENDERIZATION: POSSIBLE CAUSES AND MECHANISMS. A REVIEW.

The postmortem meat tenderizing process is complex and not fully understood. The nature of changes associated with the improvement in tenderness and the exact mechanisms involved are still unknown. Based on relevant evidence, old and new, this review attempts to clarify the statement of our knowledge of these aspects. Of the different biochemical and ultrastructural changes occurring in meat, a key role of myofibril disruption taking place at the N₂-line level in meat tenderization has been emphasized. This may be ascribed to the action of lyosomal enzymes, especially cathespin B and L. However, all the changes thus far identified can be only explained by a synergistic action of lysosomal and calcium-dependent proteinases. Besides or together with proteolytic enzymes, weakening of myofibrils may also be mediated by the high ionic strength achieved in postmortem muscles. Both mechanisms possibly involved in the meat tenderizing process have been tentatively tested in relation with the large muscle variability in aging rate. It appears that some concepts are in conflict with the results presented. For instance, no direct relationship was found between aging rate and proteinase content of muscles.     

AQUEOUS GARLIC EXTRACT AND MICROBIOLOGICAL QUALITY OF REFRIGERATED POULTRY MEAT

The antibacterial effect of garlic extract (5, 10 and 15%) was investigated on poultry carcasses obtained from a slaughterhouse, stored under refrigeration, and evaluated at selected time intervals. The effect of the garlic extract on the microbial contaminants of the poultry carcass surface – Salmonella, strict and facultative aerobic, mesophilic, and total and fecal coliforms – was evaluated. The garlic extract exhibited a concentration‐dependent reduction of microbial contamination. Garlic extract concentrations of 10 and 15% were the most effective. The bacteriostatic action of garlic extract against mesophilic microbiota can be observed until the third storage day. The count of total and fecal coliforms remained low during the storage period. Chicken feed was the apparent source of Salmonella contamination, and the aqueous garlic extract was not effective against Salmonella.     

EFFECT OF GAMMA IRRADIATION ON THE LIPID PEROXIDATION IN CHICKEN, LAMB AND BUFFALO MEAT DURING CHILLED STORAGE

Chicken, lamb and buffalo meat were subjected to low-dose gamma irradiation (2.5 kGy) and stored at 0–3C. Lipid peroxidation in terms of thiobarbituric acid (TBA) number and carbonyl content were monitored during storage. While irradiated meat showed slight increase in TBA number and carbonyl content on storage as compared to nonirradiated meat, this did not affect the sensory qualities of meat. Free fatty acid content decreased markedly on irradiation. Irradiated meats were microbiologically safe and sensorily acceptable up to 4 weeks in the nonfrozen state (0–3C) while nonirradiated meat had a shelf-life of less than 2 weeks .     

COOKING CHARACTERISTICS OF CHEVON MARINATED WITH GINGER RHIZOME EXTRACT IN DIFFERENT STORAGE PERIODS

The biceps femoris muscles of 12-month-old Osmanabadi goats in the prerigor state were chilled for 24 h at 4  ±  1C, and then cut in 3  ×  3 cm chunks and randomly divided into five groups. The chunks were marinated in ginger rhizome extract (GRE) at 1, 3, 5 and 7% along with 600 ppm of ascorbic acid, 2% sodium chloride and 0.5% sodium tripolyphosphate. The samples were packed in low-density polyethylene bags and stored at refrigerated storage condition at 4  ±  1C for 1, 3, 5 and 7 days. After storage, samples were drawn and the cooking characteristics were determined following the related storage periods. The marination of chevon chunks at 5% GRE improved the cooking yield (83.5–87.9%), cooked density (0.86–0.94%) and gain in height (10.4–8.9%), whereas reduction in diameter (10.1–8.8%) and emulsion stability (12.5–10.44%) were lower than other levels of GRE at all periods of storage.

PRACTICAL APPLICATIONS

Chevon is mostly stored at refrigeration conditions to increase its shelf life. However, there is not a limit of acceptability of chevon for the psychrophilic microorganisms that are important to estimate spoilage of refrigerated foods and also its texture. Marination of chevon with ginger rhizome extract at the 5% level along with 600 ppm of ascorbic acid, 2% sodium chloride and 0.5% sodium tripolyphosphate, and then storage at a refrigerated condition could prevent the spoilage and improve the texture. These levels of marination will be helpful in further studies to decide how long the chevon could be kept safe and tender.     

INFLUENCE OF DIFFERENT CASINGS ON SALAMI PRODUCED WITH MEAT FROM BUFFALO AND PODOLIAN CATTLE

ABSTRACT

The effect of different casings on the quality of new types of salami from buffalo and Podolian young bull meat was investigated. To this aim, three casings were used: a natural casing (NC), a modified natural casing (MNC) and a synthetic casing (SC). Their effects on processed meat were analyzed by evaluating salami quality at the end of the ripening time. Nutritional properties, microbial loads, pH, color parameters, texture and sensory properties were assessed. Moreover, the mechanical properties of the casings were measured. Results highlighted that both meat were suitable to produce salami; better results in terms of saturated and polyunsaturated fatty acids were recorded with Podolian meat. The NC and the SC exerted similar mechanical properties, very different from those of the MNC. The superior properties of the NC in terms of texture and color characteristics conferred to the fermented sausages could allow suggesting this casing as the most recommended solution to package unusual salami.

PRACTICAL APPLICATIONS

The increasing consumer interest in products with high energetic and nutritional value, authentic, tasty, rich in protein and low in lipid and cholesterol content gives rise to promote consumption of alternative meat to pork. Therefore, the influence of different casings on salami produced by boneless buffalo and young bull could be of crucial importance for industry that cares about consumer satisfaction.     

蛋白酶在猪肉脯嫩化加工中的应用研究

采用酶法嫩化技术，研究蛋白酶的种类，加酶量和酶解时间对猪肉脯嫩化的影响。结果表明，在猪肉脯生产加工中，酶法嫩化的最适条件为添加0．03％的蛋白酶C，酶解120s，肉脯嫩度、口感和营养价值都较佳。剪切力、持水力和感官评定等指标之间具有一定相关性，这为肉品嫩度预测及嫩化方法的开辟提供了思路。     

IDENTIFICATION OF POULTRY MEAT FROM PORK AND BEEF ON THE BASIS OF THE TITIN PEVK REGION USING PCR

The possibility of distinguishing three kinds of meat species (chicken, porcine and bovine) alone or in two-component meat mixtures was investigated using the polymerase chain reaction. The contribution of each component in the meat mixtures ranged from 1 to 100%. The identification of meat was performed on the basis of the sequence coding the PEVK region of titin and by employing polymerase chain reaction. DNA was isolated from raw, fresh and chilled meat. The data presented in this study suggest that it is possible to detect chicken meat, pork and beef in meat mixtures on the basis of PEVK region by using PCR.

PRACTICAL APPLICATIONS

The polymerase chain reaction (PCR) is a precise and quick technique that has many practical applications. Using PCR with primer sets designed on the basis of the PEVK region present in titin can be a convenient tool for species identification, especially for chicken meat mixed with pork and beef meat in two-component meat mixtures. Reliable and sensitive methods for species differentiation can give consumers confidence about authentic meat product composition.     

DETECTION AND CHARACTERIZATION OF VEROTOXIN-PRODUCING ESCHERICHIA COLI (VTEC) ISOLATED FROM BUFFALO MEAT

The emergence of Verotoxin‐producing Escherichia coli (VTEC) as zoonotic foodborne pathogens in recent years has become a public health concern because of its life threatening human diseases. In the present investigation, out of 87 strains of E. coli, 22 (25%) belonging to 13 different serotypes isolated from raw buffalo meat and its products were found to be verotoxic as tested by Vero cell cytotoxic assay. Serotype O26 followed by O153 and O157 were the predominant VTEC. All the VTEC strains were found positive for vt genes by polymerase chain reaction (PCR). Among the vt genotypes, vt₂(77%) was most predominant followed by vt₁(14%) and both vt₁and vt₂(9%). Production of enterohaemolysin on washed sheep blood agar supplemented with CaCl₂ showed 19 (86%) VTEC strains to be positive. Presence of VTEC in cooked buffalo meat products, namely shami kabab and kabab, appears to be a matter of concern and a potential threat to public health. VTEC detection by different methods suggests that PCR can be useful to evaluate the distribution of virulence genes (vt₁or vt₂or both) in E. coli isolates from buffalo meat and its products.     

IMPROVEMENT IN MICROBIOLOGICAL QUALITY AND SHELF-LIFE OF BUFFALO MEAT AT AMBIENT TEMPERATURE BY GAMMA IRRADIATION

The effect of low dose gamma-irradiation (2.5 kGy) on the shelf-life of prepacked fresh buffalo meat at ambient temperature (28–30C) in terms of microbiological, chemical and sensory qualities was studied. Unirradiated samples initially showed the presence of Enterobacteriaceae and Staphylococcus spp. These gradually increased during storage. After 12 h of holding , Clostridium spp. were observed in these samples. On the basis of microbiological, chemical and sensory analyses, the shelf-life was limited to 18 h. In contrast , Clostridium spp. and Enterobacteriaceae were not detected in irradiated samples throughout the storage period and Staphylococcus spp. were detected only after 12 h of holding. Irradiated samples had a shelf-life of 42 h.     

THE ANTIOXIDATIVE POTENTIAL OF LYOPHILIZED CITRUS PEEL EXTRACT IN DIFFERENT MEAT MODEL SYSTEMS DURING STORAGE AT 20C

Antioxidative potential of lyophilized citrus (Citrus unshiu) peel extract in raw and cooked meat systems was investigated. Beef pork, chicken, and salmon patties were prepared without (control), with lyophilized citrus peel extract (0.1%, NICP), and with 20 kGy-irradiated, lyophilized citrus peel extract (0.1%, ICP). TBARS value showed that the addition of lyophilized citrus peel (NICP or ICP) inhibited the development of lipid oxidation of raw and cooked meat patties during storage for 8 days at 20C (P<0.05) except for raw chicken patty. Hunter color a*-values of the cooked meat patties treated with NICP or ICP were higher than those of the control (P<0.05). Irradiation of citrus peel extract did not show any notable changes in its antioxidant effect in the meat systems. Thus, the lyophilized citrus extract could be used as one of the natural antioxidants with the potential of cost-effectiveness and is environmentally friendly.     

USE OF MECHANICAL TENDERIZATION TO INCREASE THE TENDERNESS OF BULLOCK BEEF1

The biceps femoris (BF), semimembranosus (SM) and longissimus dorsi (LD) muscles from bullocks and steers were passed through a mechnical tenderizer zero (OX), once (1X), twice (2X) or three times (3X). All three muscles were evaluated for cooking loss, cooking time and textural properties on an Instron Universal Testing machine. In addition, LD muscle steaks were presented to a sensory panel for evaluation. The passing of the SM and LD muscles through a mechanical tenderizer one or two times decreased peak load and fail energy and increased peak elongation and fail load values. LD steaks from bullocks not passed through the mechanical tenderizer (OX) were least esy to fragment, had the most detectable connective tissue and had lowest overall tenderness ratings. Passing bullock beef once (1X) through a mechanical tenderizer improved palatability ratings to a level comparable to untenderized steer beef.     

复合盐对鸡胸肉保水性影响的研究

研究几种盐单因次对鸡胸肉的保水性能的影响，并在此基础上进行正交试验，找出了影响显著的因素是柠檬酸钠和三聚磷酸钠。并确定了最佳的复合配比，可使鸡胸肉的失水率比对照降低20％。