改进型城口腊肉贮藏过程中的品质变化及货架期预测

以改进型城口腊肉为研究对象,研究在不同贮藏温度条件下其感官品质、菌落总数、酸价(acid value,AV)、过氧化值(peroxide value,POV)和硫代巴比妥酸反应物(thiobarbituric acid reactive substances,TBARS)值的变化及其相关性,以探讨改进型城口腊肉在贮藏过程中的品质变化并预测其货架期。结果表明:不同贮藏温度下腊肉的感官品质随贮藏时间的延长而逐渐降低;菌落总数、AV、POV及TBARS值均随着时间的延长而逐渐上升,且上升速率为35℃30℃25℃;通过分析不同贮藏温度下腊肉的感官评分及各理化指标之间的Pearson相关系数选出POV为货架期预测模型的关键因子;通过POV的动力学方程计算出腊肉在12、25、37℃条件下的理论货架期分别为459、93、24 d,且货架期理论值与实测值能较好符合。     

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。     

美拉德反应法制备腊肉香精的工艺优化

为制备具有抗氧化性的腊肉香精,以川味烟熏腊肉酶解液为基料,研究美拉德反应制备腊肉香精的工艺条件。采用Friedman排序检验法,对不同还原糖种类及配比、氨基酸种类、反应时间、反应温度和起始pH进行单因素试验。在单因素基础上,采用L₁₈(3⁷)正交表进行正交试验设计,以感官评价值和DPPH自由基清除能力为指标,得到制备抗氧化腊肉香精最佳工艺条件。结果表明:氨基酸为L-半胱氨酸,还原糖配比为葡萄糖(G)+木糖(X)(G+X质量比为3:1),原始pH(5.8~5.9),G+X(3:1)、L-半胱氨酸、盐酸硫胺素添加量分别为腊肉酶解液质量的4%、0.10%、0.30%,反应时间为40 min,反应温度为110℃。在此条件下得到的腊肉香精,具有饱满的腊肉香味,感官评分为8.3±0.5,DPPH清除率达到86.37%±0.51%,有较强的抗氧化性。     

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。     

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。     

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).     

不同类型烟熏香精对西式培根风味的影响

为研究不同类型烟熏香精对西式培根风味的影响,本研究通过感官评价和电子鼻技术对添加不同类型烟熏香精制作的西式培根进行整体风味的分析,利用固相微萃取气相色谱-质谱联用技术研究不同类型烟熏香精对西式培根挥发性风味物质的影响。结果表明,不同类型烟熏香精制作的西式培根与传统西式培根在整体风味和主体风味化合物上进行比较,乐香水溶性烟熏香精（样品5）差异最小,其次为名花烟熏膏香精（样品1）和奇华顿油溶性烟熏香精（样品3）,再次为红箭油溶性烟熏香精（样品2）,而红箭水溶性烟熏香精（样品4）差异最大。乐香水溶性烟熏香精制作的西式培根与传统西式培根（对照样）的挥发性风味物质比较接近,有愈创木酚、4-甲基愈创木酚、苯酚和2,6-二甲基苯酚等35种共有成分。其中酚类物质的种类和传统西式培根相同,而含量是传统的1.22倍,从宏观和微观上都可以达到传统西式培根的风味。     

粉蒸肉的生产工艺

采用感官评定的方法对粉蒸肉的配方、加工工艺进行了研究。生产工艺条件为:猪五花肉1000g,酱油23g,黄酒3g,蔗糖4g,大米115g,胡椒粉1.1g,桂皮1.8g,八角3g,丁香1.8g,姜粉1.5g,盐6g,味精4.5g,红曲色素0.03%,肥瘦质量比为6∶4,加水量15%、腌制时间60min、蒸煮时间40min。成品肉香味浓、色泽粉红,肥而不腻。     

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.