【Objective】 The objective of this experiment is to study the pyridinoline cross-links of collagen and dissect its relevance to the shear force of beef.【Method】 Samples were divided into two groups.The first group consists of the same marbling with different ages.The second consists of the same age with different marblings.The shear force of beef,solubility and hydroxylysylpyridinium,lysylpyridinium of collagen were measured.【Result】According to the results of the first group,as bull aged,HP cross-links increased,LP cross-links increased firstly,and then decreased,which was followed by the decreasing of collagen solubility and the increasing of shear force.According to the results of the second group,as fattening,HP cross-links decreased,the solubility of collagen increased,and the shear force of beef decreased.【Conclusion】In the fattening,the synthesization of HP cross-link was restrained.There are shorts of mature cross-links in collagen,resulting in transition of gelatin more easily.So beef turns tenderer.

In this paper,the pH,protein solubility,dynamic viscoelasticity and gel properties(water-holding capacity(WHC),gel strength and gel elasticity) of fresh,chilled and frozen porcine longissimus muscle were conducted comparative comparison.The results showed that pH and protein solubility of fresh meat were the highest,and the gel properties and dynamic viscoelasticities were better.The pH and protein solubility of chilled meat were relatively low,and their gel properties and dynamic viscoelasticity were inferior to those of fresh meat.The pH,protein solubility,WHC and dynamic viscoelasticity of frozen meat were the lowest,however,the gel strength and gel elasticity of frozen meat were lower than those of fresh meat and higher than those of chilled meat.Therefore,refrigeration process can damage the functional properties of meat,and functional quality of fresh meat was the best.

A large quantity of fumes may be generated as a result of frying during the production of roast chicken.PM2.5 and formaldehyde concentration in the fumes and the contents of the hazardous substances 3,4-benzypyrene and heterocyclic amines in the PM2.5 particles were determined.The maximum levels of PM2.5 and formaldehyde were detected to be 2440 μg/m3 and 0.270 mg/m3,which exhibited a 31.5-fold increase compared with China’s limit level 2 for air quality(75 μg/m3) and a 2.86-fold decrease compared with China’s atmospheric emission limit,respestively.The PM2.5 particles were detected to contain 18.35–30.68 μg/g 3,4-benzypyrene and 14.87–37.72 μg/g.

This study was focused on a comparative evaluation of the sensory quality properties and processing characteristics of striploin and knuckle meats from Yanbian and Nanyang yellow cattles. Results showed that the a * value of Yanbian beef was significantly higher than that of Nanyang beef( P < 0.05), but the L * and b * values were significantly lower than those of Nanyang beef( P < 0.05). The juiciness of striploin from Yanbian cattle was better than that of Nanyang beef, while the juiciness of knuckle was worse than that of Nanyang beef. The cooking loss showed that Yanbian beef had a higher yield during processing than Nanyang beef. The striploin of Yanbian cattle had better tenderness with shear force of 3.19 kg/cm 2, which was suitable for frying and roasting. The gel p roperty of Yanbian beef was better than that of Nanyang beef, so Yanbian beef was suitable for preparing gel-type products. Nanyang beef had a better emulsifying property, and thuswas suitable for preparing emulsification-type products.

【Objective】The objective of this study was to investigate the effect of spice,which was commonly consumed and possess high antioxidant capacities,to the content of mutagenic and carcinogenic heterocyclic amines(HAs) formed in braised sauce beef.【Method】The total phenols content and antioxidant capacities of aqueous extracts from 20 commonly consumed spices were determined by Folin-Ciocalteu colorimetric method and [2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt](ABTS) radical cation decolorization assay,respectively.Five spices among them,which contain higher total phenols contents and possess better antioxidant capacities,were further added into braised sauce beef.Contents of HAs were determined by HPLC.【Result】Blank beef sample,which was boiled with only water,contained 9H-pyrido[3,4-b]indole(Norharman) and 1-methyl-9H-pyrido[3,4-b]indole(Harman),and their total amount was very low.Beside Norharman and Harman,2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline(7,8-DiMeIQx),3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole acetate(Trp-P-1) and 3-amino1-methyl-5H-pyrido[4,3-b]indole acetate(Trp-P-2) were detected in the control sample containing soy sauce,salt and white sugar,making the total HAs content to 35.72 ng.g-1.Five selected spices,containing clove,galangal,bay leaf,red prickly ash and cinnamon bark,exhibited specific effect on the type and content of individual HA.All of the 5 spices could significantly decrease the contents of Norharman and Harman(P0.05),while their effects on the contents of 7,8-DiMeIQx,Trp-P-1and Trp-P-2 were different.In addition,bay leaf could help the formation of 2-amino-3,4-dimethylimidazo[4,5-f]quinoline(MeIQ),which was not detected in the control sample.【Conclusion】The water extracts of spices exhibited specific effect on the type and content of individual HA.Generally,red prickly ash and galangal could reduce the total HAs content,significantly inhibit the formation of 7,8-DiMeIQx without generating new HA,and thus exhibit better inhibiting effects.

Sodium tripolyphosphate added into meat was hydrolyzed irreversibly through the action of purified pyrophosphatase (PPase) and tripolyphosphatase (TPPase). The dynamic hydrolysis of tripolyphosphate (TPP) by the PPase and TPPase in bovine muscle was studied by phosphorus-31 NMR ( 31 P NMR) spectroscopy over 24.5 h. In the presence of TPPase, the first-order reaction of TPP hydrolysis was not complete within 24.5 h, and pyrophosphate (PP) derived from TPP accumulated progressively. In the presence of both PPase and TPPase, the PP produced was subsequently hydrolyzed to Pi by PPase, and TPP was completely hydrolyzed in less than 24.5 h. The results showed that TPP was hydrolyzed faster by TPPase and PPase together than only TPPase.

An analytical method was developed for the simultaneous determination of 10 heterocyclic aromatic amines (HAAs) in beef jerky by solid phase extraction-high performance liquid chromatography (SPE-HPLC). The HAAs were eluted from an Extrelut NT 20 SPE column with 60 mL dichlormethane (containing 5% toluene), and then the extract was purified with a propylsulfonic acid silica (PRS) column and a C18 SPE column, and finally, the HAAs were stored in a methanol-ammonia solution. The separation was achieved by using a TSK-gel ODS-80 column and a gradient elution with the mobile phases of acetonitrile and 0.05 mol/L acetic acid-ammonium acetate buffer (pH 3.5). The identification and quantitative analysis of the HAAs fraction were carried out using an HPLC system with ultraviolet-fluorescence detectors. The results showed that the correlation coefficients of the 10 HAAs were all above 0.999 and the limits of detection were in the range from 0.02 to 2.46 ng/g. The recoveries of the 10 HAAs spiked in beef samples were 61.69% - 101.81% with the relative standard deviations (RSDs) between 0.28% and 7.81%. 1-Methyl-9H-pyrido[4,3-b] indole (Harman) and 9H-pyrido [4,3-b]indole (Norharman) were detected in all beef jerky, and the total HAAs content of beef jerky were between 16.65 and 60.38 ng/g. This method is with wide linear range and high sensitivity, and is enough for the analysis of the HAAs in actual meat samples.

Polyphosphates have been extensively used as food additives in meat processing,however,the addition of excess polyphosphates in exported aquatic products from China has often happened in recent years.Ion chromatography method applied to the determination of polyphosphates in meat possesses the advantages of low limit of detection,high sensitivity and reproducibility,good anti-jamming ability and accurate results.This paper introduces recent research achievements on ion chromatographic determination of polyphosphates in meat and compares ion chromatography method and several other common methods,which will have some practical significance to control the addition of polyphosphates and ensure meat safety.

A method was developed for the simultaneous determination of 9 heterocyclic aromatic amines (HAAs) including 2-amino-3-methylimidazo[4,5-f] quinoline (IQ), 2-amino-3,4-dimethylimidazo[4, 5-f] quinoline (MeIQ), 2-amino-3, 8-dimethylimidazo [4, 5-f] quinoxaline (MeIQx), 2-amino-3, 4, 8-trimethyl-imidazo [4,5-f quinoxaline (4,8-DiMeIQx), 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP), 3-amino-1 -methyl-5H-pyrido [4, 3-b] indole (Trp-p-2), 3-amino-1, 4-dimethyl-5H-pyrido [4,3-b] indole (Trp-p-1), 9H-pyrido [3,4-b] indole (Norharman), 1-methyl-9H-pyrido 3, 4-b] indole (Harman)) in poultry products using solid-phase extraction-high performance liquid chromatography (SPE-HPLC). The performance of 3 different organic extraction solutions, 2 solid phase extraction (SPE) procedures, three different reversed-phase columns and five different mobile phases were tested for optimizing separation conditions of the 9 HAAs from poultry products. In the end, ethyl acetate was selected as the extraction solution, and the extract was purified with propylsulfonic acid silica (PRS) and C18 SPE columns. The analysis was performed on a TSK-gel ODS-80TM column using a gradient elution with the mobile phases of 0.05 mol/L aqueous acetic acid-ammonium acetate buffer (pH 3.4) and acetonitrile. The results showed that the average recoveries (n = 6) of the 9 HAAs spiked in meat samples at 3 levels ranged from 60.47% to 90.55% with the relative standard deviations (RSDs) between 0.49% and 9.74%, and the limits of detection (LODs, S/N = 3) were in the range of 0.1 - 3.6 microg/kg. The method is simple, rapid, accurate and sensitive enough for the analysis of HAAs in poultry products.

Carbonado is a typical representative of the Chinese traditional poultry products,which has been well received by consumers.Studies showed that carbonados produced by traditional processing method contain a variety of hazardous compounds including trans fatty acids,oil oxides,polycyclic aromatic hydrocarbons and heterocyclic aromatic amines.Non-fried,non-salt boil,non-grill,and non-smoked poultry product processing technology can not only effectively inhibit the formation of harmful compounds in carbonado,but also realize the industrialization of carbonado processing,thus becoming an ideal technology for carbonado processing.The hazardous compounds in carbonado and their hazards to the human body are summarized.Main technical innovations of new technologies for carbonado processing are briefly introduced.In addition,a perspective on their future applications is presented.

Smoked meat products are very popular worldwide.The traditional smoking technology has defects,easily leading to the pollution of polycyclic aromatic hydrocarbons(PAHs) and formaldehyde.This paper outlines some defects of the traditional smoking technology and put forward the solutions: inhibiting the formation of PAHs and using liquid smoking.The first solution has limitation and can not solve the problem of formaldehyde pollution.However,the second not only retains the flavor of traditional smoked meat products,but also yields safe and healthy products,thus being worth advocating and popularizing.