重庆城口腊肉挥发性风味化合物分析

以真空包装和散装2 种包装方式、秋季和冬季生产的重庆城口腊肉为研究对象,采用顶空固相微萃取和气相色谱-质谱联用技术分析重庆城口腊肉的挥发性风味成分。结果表明：在相同的生产季节,不同包装方式的腊肉样品中酯类、酚类和碳氢化合物相对含量变化明显,醛类和醇类物质相对含量变化不明显。在相同的包装条件下,不同季节生产的腊肉样品中酚类和碳氢化合物相对含量变化明显,酯类、醛类和醇类物质相对含量变化不明显。此外,腊肉的特征性挥发风味成分主要来自于酚类、醇类、醛类等,如3-甲基愈创木酚、4-甲基愈创木酚、愈创木酚、2,5-二甲基苯酚、己酸甲酯、甲苯酸丁酸酯、正己酸乙酯等。     

四川腊肉生产过程中理化、生化特性的研究

研究了四川腊肉生产过程中的理化、生化特性的变化情况。结果表明,腊肉的pH值在腌制的前期、烟熏的后期和成熟期间下降;总酸在腌制前期显著上升;在生产过程中腊肉的水分含量、水分活度和总糖含量逐渐下降,食盐含量逐渐升高;在生产过程中TBA值、过氧化值、酸价都呈逐渐上升趋势;成熟后产品的非蛋白氮和氨基酸态氮含量都比原料肉中的含量有显著增加,可溶性总氮含量与原料肉中的含量相比无显著变化,挥发性盐基氮在整个生产期间一直呈上升趋势。     

Survival and death of Listeria monocytogenes on cooked bacon at three storage temperatures

Survival of Listeria monocytogenes on cooked bacon cubes (a_w 0.910 ± 0.080), strips (a_w 0.726 ± 0.054), and bits (a_w 0.620 ± 0.038) was determined during a 25 week storage period at −20, 4.4, and 22 °C. Selective enrichment and subsequent enzyme-linked fluorescent antibody (ELFA) detection were used to asses survival on samples inoculated at ca. 1-log₁₀ CFU/g (LI). Samples inoculated at ca. 5.5-log₁₀ CFU/g (HI) were analyzed over time by direct plating on modified Oxford medium (MOX). The Baranyi model was fitted to the inactivation curves of HI samples using the DMFit program. At −20 °C, a decline of about 1-log₁₀ CFU/g occurred on all HI cooked bacon types by 14 weeks, although most LI samples remained positive by the ELFA detection method for 25 weeks. At 4.4 and 22 °C, some strips and bits LI samples were negative for the pathogen within 3 weeks, and >1.5 log₁₀ CFU/g reductions occurred on HI strips and bits by 8 weeks. Reductions on cubes at refrigeration and ambient temperature were ca. 0.5 log₁₀ CFU/g, and cubes remained positive on LI samples for 25 weeks. Rate parameter estimates indicated that the population declined fastest on strips and bits at 22 °C compared to all other product and temperature combinations. This study demonstrates that cooked bacon does not support the growth of L. monocytogenes and that the pathogen gradually dies off during storage.     

Nonane as a Radiolytic Product in Irradiated Bacon

Formation of nonane in irradiated bacon has been confirmed by gas chromatographic/mass spectrometric (GC/MS) analysis of irradiated nitrogen-flushed homogenized bacon in sealed glass vials. Unirra-diated bacon did not show the presence of nonane under similar conditions.     

Modeling microbial competition in food: application to the behavior of Listeria monocytogenes and lactic acid flora in pork meat products

Competition between background microflora and microbial pathogens raises questions about the application of predictive microbiology in situ, i.e., in non-sterile naturally contaminated foods. In this article, we present a review of the models developed in predictive microbiology to describe interactions between microflora in foods, with a special focus on two approaches: one based on the Jameson effect (simultaneous deceleration of all microbial populations) and one based on the Lotka-Volterra competition model. As an illustration of the potential of these models, we propose various modeling examples in estimation and in prediction of microbial growth curves, all related to the behavior of Listeria monocytogenes with lactic acid bacteria in three pork meat products (fresh pork meat and two types of diced bacon).     

Thermal Stability of Total Lipids Extracted from Zlatibor Bacon

In this study, non-oxidative and oxidative thermogravimetric analysis was applied as a method for determining the thermal stability of the total lipids extracted from Zlatibor bacon in different phases of production (raw samples, 10th and 30th day of smoking and 30th day of storage). The activation energies of the thermal degradation and oxidation of the total lipids extracted from examined samples were determined. A moderate increase of the activation energy, as well as the other information gained from TG analyses, indicated that there were no significant oxidative changes in Zlatibor bacon lipids during the production and storing.     

Effects of Retail Style or Food Service Style Packaging Type and Storage Time on Sensory Characteristics of Bacon Manufactured from Commercially Sourced Pork Bellies

Objectives were to characterize differences in pork bellies that were stored frozen for different durations prior to processing and characterize sensory properties of the bacon derived from those bellies when stored in either retail or food service style packaging. Bellies (n = 102) were collected from 4 different time periods, fresh bellies (never frozen) and bellies frozen for 2, 5, or 7 mo, and manufactured into bacon under commercial conditions. Food service bacon was packaged in oxygen‐permeable polyvinyl lined boxes layered on wax‐covered lined paper and blast frozen (–33 °C) for 45 or 90 d after slicing. Retail bacon was vacuum‐packaged in retail packages and refrigerated (2 °C) in the dark for 60 or 120 d after slicing. At the end of respective storage times after slicing, bacon was analyzed for sensory attributes and lipid oxidation. Off‐flavor and oxidized odor of bacon increased (P < 0.01) with increasing storage time in both packaging types. Lipid oxidation increased (P < 0.01) as storage time increased from day 0 to day 45 in food service packaged bacon from frozen bellies, but was unchanged (P ≥ 0.07) with time in food service packaged bacon from fresh bellies. Lipid oxidation was also unchanged (P ≥ 0.21) over time in retail packaged bacon, with the exception of bellies frozen for 5 mo, which was increased from day 0 to day 90. Overall, off‐flavor, oxidized odor, and lipid oxidation increased as storage time after processing increased. Freezing bellies before processing may exacerbate lipid oxidation as storage time after processing was extended.     

响应面试验优化低盐湘西腊肉复配防腐剂的配方

研制一种延长低盐湘西腊肉贮藏期限的复配防腐剂。采用响应面法,以抑菌率为响应值,考察柠檬酸、双乙酸钠和Nisin（乳酸链球菌素）用量对抑菌率的影响,优化复配防腐剂配方,并测定了复配防腐剂对低盐湘西腊肉的实际贮藏效果。结果表明：柠檬酸、双乙酸钠和Nisin对低盐湘西腊肉中的微生物有较强抑制作用;双乙酸钠和Nisin、柠檬酸和Nisin复配对抑菌均存在协同增效效应,且前者增效强于后者,但柠檬酸和双乙酸钠间无增效作用;复配防腐剂最优配方为柠檬酸用量1.20 g/kg、双乙酸钠用量0.97 g/kg、Nisin用量0.16 g/kg,以此配方处理低盐湘西腊肉抑菌率达95.98%,腊肉贮藏期限达160 d。     

复合抗菌膜对腊肉品质的影响

采用羧甲基纤维素(CMC)与明胶制作复合型抗菌膜用于腊肉的防腐保鲜。以膜的水蒸气透过率、膜的厚度和透光度为主要指标,对膜液的组成进行优化,以此为基础加入适量的山梨酸钾,制备出具有良好性能的复合型抗菌膜。结果表明,将CMC与明胶以质量比1:2的比例配制成质量浓度10g/L的成膜液,添加质量分数0.4%的甘油和0.08%的山梨酸钾制成复合抗菌膜,对腊肉进行涂膜保鲜够延缓腊肉的腐败速度,延长贮藏时间。