Epoxides bearing azomethine linkages

Seven structurally different diepoxides, triepoxides or tetraepoxides bearing azomethine linkages were synthesized and characterized. The reactions of 4-hydroxybenzaldehyde or 3,4-dihydroxybenzaldehyde with 4-aminophenol or 4-aminobenzoic acid afforded azomethines, which reacted subsequently with excess of epichlorohydrin in the presence of benzyltrimethylammonium bromide to yield diepoxides or triepoxides. Triepoxides were prepared by reacting 4-hydroxybenzaldehyde with 5-aminoisophthalic acid or 4-amino-2-hydroxybenzoic acid again to yield azomethines, which were subsequently reacted with epichlorohydrin. In addition, a tetraepoxide was prepared from the reaction of 1,4-benzenedicarbaldehyde with a double molar amount of 4-amino-2-hydroxybenzoic acid to afford a bisazomethine followed by reaction with epichlorohydrin. The epoxy compounds were characterized by IR and ¹H NMR spectroscopy. Their thermal polymerization in the presence of 4,4-diaminodiphenylsulfone (DDS) was investigated by DTA. Thermal stabilities of cured resins were ascertained by TGA and isothermal gravimetric analysis (IGA) in N₂ or air. The polymer derived from the tetraepoxide was the most heat-resistant. It was stable in N₂ up to 313°C and afforded an anaerobic char yield of 58% at 800°C.     

Control of Listeriamonocytogenes on commercially-produced frankfurters prepared with and without potassium lactate and sodium diacetate and surface treated with lauric arginate using the Sprayed Lethality in Container (SLIC®) delivery method

Viability of Listeriamonocytogenes was monitored on frankfurters formulated with or without potassium lactate and sodium diacetate at a ratio of ca. 7:1 and treated with lauric arginate (LAE; 22 or 44 ppm) using the Sprayed Lethality in Container (SLIC®) delivery method. Without antimicrobials, pathogen numbers remained relatively constant at ca. 3.3 log CFU/package for ca. 30 d, but then increased to ca. 8.4 log CFU/package over 120 d. Regardless of whether or not lactate and diacetate were included, when treated with LAE, pathogen numbers decreased from ca. 3.3 log CFU/package to ca. 1.5 log CFU/package within 2 h, but then increased to 7.3 and 6.7 log CFU/package, respectively, after 120 d. When frankfurters were formulated with lactate and diacetate and treated with LAE, pathogen numbers decreased by ca. 2.0 log CFU/package within 2 h and remained relatively unchanged over the 120 d. These data confirm that LAE provides an initial lethality towards L. monocytogenes and when used in combination with reduced levels/ratio of lactate and diacetate as an ingredient for frankfurters provides inhibition throughout shelf life.     

Effects of dietary Chinese cured meat on lipid metabolism in rats

The effects of different fats on animal lipid metabolism were investigated in order to clarify the safety of cured meat. The physical effect of nitrite in the cured meat was also explored due to a increased concern of this compound as a food additive. Body weight, food intake, organ/body weight ratio and plasma lipid profiles were analyzed. Rats fed with cured meat fat did not show any differences in body weight and food intake, compared with the control, and no significant difference was observed among groups. However, lard-fed rats showed marked morphological alternations in aortic intima and liver tissue. The cured meat group did not show apparent morphological changes on aorta intima compared to the control. Rats that received lard diet had significantly elevated TC (2.27 ± 0.46 mmol/ml), higher LDL-C (0.78 ± 0.31 mmol/ml) but lower HDL-C (1.55 ± 0.14 mmol/ml). Lard-fed rats had elevated oxidized LDL in serum and MDA level in blood and liver. However, diets containing fresh fat (with/without added nitrite) or cured meat fat failed to show these detrimental effects.     

Effect of Iberian × Duroc genotype on composition and sensory properties of dry‐cured ham

BACKGROUND: Dry‐cured ham quality from three different Iberian × Duroc genotypes was studied: GEN1, Iberian × Duroc1; GEN2, Duroc1 × Iberian; GEN3, Duroc2 × Iberian. GEN1 and GEN2 are reciprocal crosses, while the difference between GEN2 and GEN3 is the Duroc sire line. The line Duroc1 (DU1) was selected for the manufacture of dry‐cured meat products, whereas the line Duroc2 (DU2) was selected for meat production with low carcass fat. RESULTS: Dry‐cured hams from all genotypes had similar chemical composition. However, intramuscular fat of dry‐cured hams from GEN3 was more unsaturated than that from GEN2, while GEN1 was intermediate. Lipid oxidation, measured as 2‐thiobarbituric acid‐reactive substances (TBARS) and hexanal content, was similar between genotypes. The colour of hams was affected by genotype; hams from GEN2 showed higher lightness (CIE L*), while those from GEN3 had a less intense colour (lower a* and C*). Texture measured instrumentally did not differ between genotypes; however, in the sensory analysis, panellists considered hams from GEN3 more fibrous, while those from GEN2 were considered juicier. Hams from GEN3 were also perceived as saltier and more acid. CONCLUSION: Genotype affected the quality of Iberian hams, with those from GEN3 being of lower quality, and this genotype was considered less suitable for the manufacture of Iberian dry‐cured ham. Copyright © 2007 Society of Chemical Industry     

肉类保藏技术(六) 辐照技术及其在肉类食品保藏中的应用

辐照技术是一种新型的冷杀菌技术,具有无残留、无污染、高效、节能等优点,因此在食品保藏中广泛应用。辐照处理不仅能有效提高肉品的卫生安全性、延长其保质期,并可最大程度地保持肉品的原有营养价值和感官特征,因此备受人们关注。本文主要介绍了食品辐照技术的原理、优点及辐照对肉品营养成分的影响、辐照肉品的安全性、辐照技术的在肉品保藏中的应用,并对辐照技术在肉品保藏中应用的前景进行了展望。     

腌腊肉制品的低温干燥工艺

研究南京香肠、南京香肚、广式香肠、肉枣的低温干燥工艺。结果表明:在温度5～8℃,湿度40%～50%,低温干燥时间分别为:南京香肠(d38～40mm干肠衣)192h,广式香肠、肉枣(d22mm胶原蛋白肠衣)为120h,香肚(d49～51mm)为330h。低温干燥工艺会使产品酸价、过氧化值明显降低,产品更加营养、安全、健康。     

Improving water retention of chicken breast meats by CaCl2 combined with pulsed electric fields

Frozen poultry meat is the most widely consumed animal-based food. However, water loss often leads to quality loss of poultry meat. Therefore, the present study sought to investigate the combined effect of calcium chloride (CaCl₂) and pulsed electric fields (PEF) treatment on chicken breast meats and the mechanisms underlying protein degradation. The results showed that the synergistic effect was superior to the single treatment. Compared with the untreated group, the combination of CaCl₂ and PEF increased water holding capacity of chicken breast meats by 16.61% and decreased cooking loss by 28.93%. Low-field nuclear magnetic resonance (LF-NMR) results indicated that the synergistic treatment promoted water molecules' binding capacity in myofibrils of poultry meat, which exhibited higher immobilised water. Additionally, the combination of CaCl₂ and PEF led to increased degradation of proteins of high-molecular weight and surface hydrophobicity of myofibrillar protein. Furthermore, the extension of the protein molecule and microenvironmental changes promoted interaction between protein and water. In conclusion, the synergistic treatment of CaCl₂ and PEF enhanced water retention and improved physicochemical properties of the myofibrillar protein in chicken breast meats.     

Dietary oxidised lipids,health consequences and novel food technologies that thwart food lipid oxidation: an update

Processed foods are popular and their consumption is expected to grow globally. Food processing and manufacturing promote lipid oxidation in foods rich in polyunsaturated fatty acids and cholesterol. This review focuses on how various food manufacturing/processing techniques promote lipid oxidation in grains, meats and meat products, dairy and fats/oils. This review also considers emerging evidence from animal and human studies that suggest a link between dietary oxidised lipid consumption and chronic disease risk. An update on novel food technologies that limit food lipid oxidation is discussed so as to inform both food scientists and dietitians/nutritionists to direct future efforts in not only continuing to bring these novel technologies to the market place but also conduct clinical trials to establish their role in human health.     

Behaviour of food-borne pathogens on dry cured sausage manufactured with herbs and spices essential oils and their sensorial acceptability

Dry cured sausages such as Portuguese chouriço de vinho are made generally with roughly minced pork and fat and seasoned with a large variety of herbs and spices. It is a particular sausage because meat is marinated in wine with other seasonings during 24–48 h before stuffing. Nowadays, health concerns of consumers have left food processors with less flexibility to choose preservative substances and methods. Thus, the objective of this study was to assess the antimicrobial effect of essential oils (EOs) of herbs and spices traditionally used in seasoning dry cured sausage chouriço against Salmonella spp., Listeria monocytogenes and Staphylococcus aureus. First, antibacterial activity of 14 EOs was screened by disk diffusion assay. Those EOs that displayed antimicrobial activity were further characterized by GC–MS and added as natural antimicrobial substances to the manufacture of chouriço at two concentrations (0.005% and 0.05%). Samples were analyzed 24 h after the preparation of the batter and after 3, 8, 15 and 21 days.After 15 days of drying, Salmonella spp. and L. monocytogenes counts decreased by ca. 2 log cfu/g in all samples. At 3 days, Salmonella spp. was already undetectable in chouriço made with 0.05% of garlic and oregano EOs. Both Salmonella spp. and L. monocytogenes were not detected after 8 and 15 days of drying respectively. S. aureus was still presented after 21 days of drying although its counts were not high enough to a potential enterotoxins presence. Utilization of EOs in manufacture of dry cured sausage resulted in an interesting strategy to improve its safety against Salmonella spp, L. monocytogenes and S. aureus, but with sensory limitations, that does not allow its use in high concentrations, that are those more interesting for pathogen inhibition.However, results with good potential to be applied by the industry were found, once the level of addition of 0.005% contributed for significant reductions on the pathogen's counts and for a shorter period to achieve the not detectable level, allowing the industry to shorten the drying period and, thereafter increasing yield production.