生鲜面条储藏过程中微生物指标、理化性质及组分变化规律

研究了不同温度条件下生鲜面条储藏过程中微生物指标、理化性质(酸度和L~*)的变化,同时对生鲜面条组分包括蛋白质、淀粉和水分的变化进行了研究。结果表明:在25、10、4℃条件下,随着储藏时间的延长,菌落总数和霉菌酵母数量均呈增大趋势,并且25℃的菌落总数在第1 d超过3×10~5 CFU/g,而10℃和4℃菌落总数分别在第3 d、第7 d超过3×10~5CFU/g。理化性质表现为酸度增大、L~*降低。另外,在不同温度条件下,面条的组分储藏过程中表现为蛋白质降解、淀粉峰值黏度降低。核磁共振结果表明,随着储藏时间延长,T_2增大,A_(23)增加,水分子的自由度变大。本研究明确了生鲜面条储藏过程中微生物指标、理化性质及组分的变化,能够为生鲜面条的保鲜工艺提供借鉴。     

不同贮藏条件下菠菜生鲜面的品质分析

以菠菜生鲜面为研究对象,以水分含量、水分活度、p H、酸度、色泽、叶绿素含量、感官属性、菌落总数为考核指标,在4℃和25℃条件下系统研究光照、避光、充CO2等3种贮藏方式对产品品质影响。实验结果:在4℃和25℃条件下,3种贮藏方式中菠菜生鲜面的水分含量、水分活度、p H、色泽、叶绿素含量、感官属性随贮藏时间的延长逐渐下降,酸度和菌落总数逐渐上升;4℃、充CO2的贮藏方式,产品的品质最优;贮藏5 d的感官评分和菌落总数分别为7.1、8.7×104CFU/g,为产品的品质裂变转折点;菠菜生鲜面感官品质、菌落总数与产品的水分含量、酸度、水分活度、p H、总叶绿素、叶绿素a、叶绿素b、L*、a*、b*具有相关性。本研究通过对贮藏品质的探讨,为产品的货架期延长、突破制约产业化发展的技术瓶颈提供重要的数据支撑。     

贮藏温度和时间对哈尔滨红肠微生物菌相变化及理化性质的影响

研究贮藏温度和时间对哈尔滨红肠微生物菌相及理化性质的影响。将红肠贮藏在4 ℃ 或室温（（20±2）℃）条件下,研究第0、2、4、6天红肠菌落总数、乳酸菌、假单胞菌和葡萄球菌的数量变化,并分析不同贮藏温度和时间对红肠的感官、pH值、硫代巴比妥酸值、红色度（a*值）、亮度（L*值）及质构特性的影响。结果表明,在0～2 d菌落总数增长速率最快,6 d室温红肠样品菌落总数和葡萄球菌显著多于4 ℃的红肠样品（P＜0.05）。乳酸菌和假单胞菌在6 d数量较多,其中4 ℃和室温贮藏的红肠中假单胞菌分别上升到5.1（lg（CFU/g））和6.2（lg（CFU/g））。随着贮藏时间的延长,红肠的感官质量逐渐降低,pH值也逐渐降低,而硫代巴比妥酸值逐渐增大。a*和L*值变化不大,质构特性中硬度和咀嚼性逐渐变大,弹性和黏聚性的变化不大。研究表明假单胞菌和乳酸菌是红肠贮藏过程中主要的优势腐败菌,随着贮藏时间延长红肠的质量下降。     

鲜熟面条贮藏品质变化及货架期研究

为了明确鲜熟面条在不同贮藏温度下品质指标的变化情况,确定出不同贮藏温度下鲜熟面条的货架期,将制作好的鲜熟面条分别于0、4、10、15、20、25℃条件下贮藏,定期取样,测定其感官品质、pH值、质构品质和菌落总数,分析各项指标随贮藏时间的变化及其差异。结果表明,不同贮藏温度下,随着贮藏时间的延长,鲜熟面条的感官品质、pH值、弹性和黏聚性逐渐降低,硬度则先增大后减小,菌落总数逐渐增大;在0、4、10、15、20、25℃的贮藏条件下,鲜熟面条的货架期分别为126、91、17、11、5、4 d;pH值、菌落总数是评价鲜熟面条货架期较好的指标,其阈值分别为6.24和10~(5.87)CFU/g;温度对鲜熟面条品质及货架期有显著影响,低温(0、4℃)贮藏可使鲜熟面条货架期延长至3个月以上。     

复配型护色剂对菠菜生鲜面贮藏品质的调控

本研究通过色差和感官评分为目标参数,探讨复配型护色剂氯化钠、D-异抗坏血酸钠、叶绿素铜钠添加量对菠菜生鲜面色泽和品质的影响,以及3种添加剂调控菠菜生鲜面色泽和品质的协同效应。研究表明在25℃和4℃下,正交实验优化配方为D-异抗坏血酸钠添加量0.06%、叶绿素铜钠添加量0.015%、氯化钠添加量1.50%。由验证性实验可知,在25℃和4℃的储藏温度下菠菜生鲜面中多酚氧化酶和过氧化酶的酶活力与对照组相比受到明显的抑制作用;在25℃条件下储藏2 d菌落总数达到5.41±0.04 lg(CFU/g),而4℃条件下贮藏28 d内则在5.48 lg(CFU/g)以下,在同样贮藏时间下,比对照组菌落总数少,且4℃储藏环境更适合生鲜面的贮藏。同时,在25℃条件下储藏3 d内最优组酸度为1.47 mL/10 g,在4℃条件下储藏21 d内其酸度为1.23 mL/10 g,均低于对照组。此外,叶绿素含量和p H则都高于对照组,说明提出的复配型护色剂对菠菜生鲜面贮藏过程中色泽和品质变化起到一定的积极作用。本研究通过复配型护色剂对菠菜生鲜面贮藏过程中色泽和品质变化的探讨,为产品的护色、延长货架期等商业化发展提供理论支持。     

4 ℃贮藏期内冷鲜羊肉表面菌相变化分析

研究4 ℃条件下贮藏时间对冷鲜羊肉表面菌相组成的影响,以菌落总数为指标,结合菌落聚合酶链式反应法,了解冷鲜羊肉在其贮藏期内的菌群构成,以及随着贮藏时间延长其优势菌群的变化。结果表明,冷鲜羊肉在4 ℃托盘贮藏条件下,菌落总数随贮藏时间的延长而增加,第7天其菌落总数超过106 CFU/g,样品已经腐败变质;其表面主要菌群包括假单胞菌属、芽孢杆菌属、不动杆菌属等。随着贮藏时间的变化,假单胞菌占总菌相的大部分,是造成冷鲜羊肉腐败变质的主要优势菌。     

0℃冷藏三文鱼片新鲜度综合评价

对0℃贮藏的三文鱼片的理化指标和微生物指标【包括挥发性盐基氮(TVB-N)值、2-硫代巴比妥酸(TBA)值、p H值、色差值、菌落总数】进行定期测定,用电子鼻分析其挥发性气味组分(包括主成分分析、负荷加载分析以及线性判别分析);结合感官评价,探究冷藏条件下三文鱼片新鲜度的变化规律。试验结果表明:0℃贮藏的三文鱼片的TVB-N值、TBA值、菌落总数都随贮藏时间的延长而增大;p H值先降低后增高;色差值L*值先增加后减小再增加,a*值与b*值与其相反;总色差值则先增加后减小;感官评定分数一直下降。采用电子鼻能很好地区分不同贮藏时间的三文鱼片,各理化指标间有很好的对应关系(P0.01)。     

玉米薄饼贮藏品质分析及货架期预测模型建立

为探索玉米薄饼贮藏品质变化规律,以玉米粉和小麦粉为原料制备韧性玉米薄饼,研究玉米薄饼贮藏14 d内感官品质、理化指标、微生物指标、质构及老化特性的变化,探讨影响玉米薄饼贮藏品质变化的主要因素,建立玉米薄饼货架期预测模型。结果表明：贮藏在4、25 ℃和40 ℃ 3 种温度条件下,玉米薄饼的酸值、过氧化值、菌落总数、热焓值、b*值随贮藏时间的延长逐渐增大;韧性、延展性、L*值、a*值、感官评分逐渐降低。通过相关性分析得出菌落总数可以作为反映玉米薄饼贮藏货架期的品质因子,建立不同温度条件下菌落总数生长动力学模型及随贮藏温度变化的动力学模型,其准确因子为1.126～1.281,偏差因子为0.899～1.051。在此基础上建立韧性玉米薄饼货架期预测模型,预测值和实际值的相对误差为－4.10%～2.91%,模型能够快速可靠地预测饼的货架期,可为玉米饼及相关制品的工业化生产提供技术和理论依据。     

典型冷链贮藏南美白对虾优势菌菌相变化与感官品质相关性分析

将南美白对虾在典型冷链温度-23,0,5℃条件下贮藏,通过菌落计数与观察、革兰氏染色、生理生化试验对优势菌进行鉴定,结合感官评分和细菌总数变化规律,分析南美白对虾在典型冷链贮藏温度下优势菌菌相变化与感官品质的相关性。结果表明:典型冷链贮藏温度5℃条件下,南美白对虾细菌总数在第3天时超过6.2 lg(CFU/g),0℃条件下细菌总数在第5天超过6.0 lg(CFU/g),-23℃条件下的细菌总数一直低于4.0 lg(CFU/g)。分离纯化的4种优势菌被鉴定为黄杆菌属、假单胞菌属、不动杆菌属和葡萄球菌属,其中黄杆菌属与假单胞菌属占70%以上,是延长南美白对虾货架期的关键控制菌。结合菌相变化的感官评价表明,0℃和5℃条件下南美白对虾分别经3 d和5 d的贮藏,感官价值大大降低;而-23℃条件下贮藏30 d,其感官品质无明显下降。     

PCR-DGGE结合生理生化鉴定分析冷藏金枪鱼细菌菌相变化

以感官、色差、质构、挥发性盐基氮(TVB-N)、K值以及菌落总数、嗜冷菌总数为鲜度指标,研究4℃冷藏金枪鱼贮藏期间品质变化;并结合生理生化鉴定和16S rDNA,应用变性梯度凝胶电泳(DGGE)指纹图谱技术,分析冷藏金枪鱼主要微生物的菌相演替变化规律。结果表明:冷藏期间,金枪鱼感官品质劣变明显,亮度值L*、红度值a*和咀嚼性、硬度均呈下降趋势;贮藏第4天,菌落总数自3.60 lg (CFU/g)升至4.66 lg (CFU/g),而嗜冷菌数与菌落总数之间的差异减小;贮藏第6天,TVB-N值与K值分别由初始值9.62 mg/100 g和3.22%上升至25.00 mg/100 g和23.00%;不同冷藏时期的金枪鱼中微生物群落结构具有相似性,样品初始菌相中主要优势菌为噬氢菌、不动杆菌、假单胞菌、解糖假苍白杆菌、Boseaeneae、鞘氨醇单胞菌和油短波单胞菌。随着贮藏时间的延长,微生物多样性降低,至货架期终点第6天,红游动菌、约氏不动杆菌、假单胞菌、解糖假苍白杆菌成为主要优势腐败菌。     

市售鲜湿米粉菌落总数及大肠菌群数繁殖动态的考察

目的 考察南宁市售不同厂家的鲜湿类米粉的菌落总数、大肠菌群污染状况及后续繁殖动态。方法 按照GB 4789.1-2016《食品安全国家标准 食品微生物学检验 总则》抽样方法, 从餐饮店抽取6批不同厂家的未开封的鲜湿米粉。按照GB 4789.2-2016《食品安全国家标准 食品微生物学检验 菌落总数测定》、GB 4789.3-2016《食品安全国家标准 食品微生物学检验 大肠菌群计数》的检测方法, 分别在0、2、4、8、12、16、24 h对样品的菌落总数及大肠菌群项目进行检测, 在24 h同时取部分样品在沸水中焯1 min后平行检测, 对计数结果进行分析。结果 0 h时, 各样品的菌落总数在3.1×103~6.9×107 CFU/g, 大肠菌群在0~8.5×105 CFU/g。在22 ℃条件放置下, 随着时间推移, 各样品的菌落总数和大肠菌群数仍不断增殖。16 h(即保质期过后), 菌落总数达到7.2×107~1.9×109 CFU/g左右, 繁殖基本趋缓。24 h时, 在沸水中焯1 min后, 所有样品的菌落总数小于1.3×103 CFU/g, 大肠菌群均小于10 CFU/g, 远低于标准规定。结论 22 ℃储藏条件下并不能遏制鲜湿米粉的菌落总数及大肠菌群增殖, 沸水焯1 min可有效降至安全水平。     

微酸性电解水杀菌工艺优化及对云南鲜米线贮藏品质影响

为优化微酸性电解水（Slightly Acidic Electrolyzed Water,SAEW）对鲜米线杀菌工艺条件,探明其对米线储藏过程品质变化规律;以微酸性电解水处理温度、处理时间与料液比为自变量,鲜米线表面微生物杀灭对数值为响应值,应用响应面法优化其最佳处理条件。以最佳处理参数处理鲜米线,以无菌水处理样品作为对照组（CK）,两组样品均置于27℃恒温箱中储藏,定期测定其表面菌落总数、含水量、酸度、pH、色差等指标,探讨SAEW处理对鲜米线贮藏品质变化影响。得出其最佳处理条件为,温度21℃、时间15 min、料液比1：16（m：V）。在此工艺条件下计算所得菌落总数死亡数量级的理论值为3.09 lg CFU/g。进行3次验证实验实际平均菌落死亡数量级为（3.01±0.09） lg CFU/g。在此条件下,SAEW处理能有效控制样品表面微生物数量,同时可延缓褐变及总酸度的增加,减少水分含量的丧失,对pH无显著影响。处理后的鲜米线在贮藏储藏48 h后,表面菌落总数为7.46 lg CFU/g,总酸度为0.392 g/100 g,分别低于对照组的8.73lg CFU/g和0.49 g/100 g。色差值为39.73,水分含量0.69,高于对照组的35.57和0.65。pH为4.64。综合表明,SAEW处理野生菌不仅能控制其表面微生物增长量,还能减缓贮藏品质的劣变速度,该结果可为研究微酸性电解水在鲜湿米线加工中的应用提供理论依据。     

Effects of the Different Temperature and Saccharose Concentrations on Some Microbiological and Chemical Characteristics of Medlar Pickle

In the production of medlar pickle was used saccharose concertrations of 0.0%, 30% and 50% as basis of water. Preparing pickles were stored at 10°C and 20°C. During the storage period, the level of acidity and lactic acid bacteria (LAB) counts of pickle samples increased while the levels of pH decreased. This situation was slow in pickles stored at 10°C. The increase of saccharose concentration caused an increase in acidity and LAB count of pickles. The values of the final acidity (%) and pH of the pickles were 1.29 and 3.46, respectively. Lactic acid bacteria counts also increased during the storage period and reached to 108 CFU/ml at the end of 8 weeks. The increase of temperature shortened fermentation duration but mold growth on surface of pickles was abserved.     

SHELF-LIFE OF FRESH-LIKE READY-TO-USE DICED SQUASH

The shelf-life of fresh-like ready-to-use diced squash during storage for 16 days at 10–12C and 95% of relative humidity was investigated. The ascorbic acid (AA) content, moisture, soluble solid content, titratable acidity, pH, weight loss and microbiological counts were determined. At the end of storage, a 1.5% weight loss was observed. Water content did not show significant changes during storage. The soluble solids content and the Brix/titratable acidity ratios increased during storage, following a linear correlation. The evolution of AA content followed a 2° polynomial correlation, with a maximum between 7–9 days of storage and a final value of 17 mg AA/100 g of fresh weight. The total microbial count increased continuously throughout storage but showed an acceptable level until day 10.     

Sodium Lactate Effects on Shelf-Life, Sensory, and Physical Characteristics of Fresh Pork Sausage

The objective of our study was to evaluate the effects of various levels (0%, 1%, 2%, 3%) of sodium lactate on selected physical, sensory, and microbiological characteristics of fresh pork sausage stored at 4°C for 28 days. Samples containing 0% and 1% SL reached 10⁸ CFU/g after 10 days refrigerated storage. Addition of 2% or 3% SL to fresh pork sausage delayed microbial deterioration, pH decline, and development of sour- and off-flavors 7 days at 4°C. Samples containing 2% SL did not reach total plate counts of 10⁸ CFU/g until 24 days storage. SL appeared to protect red color, and to “enhance” pork-and salty-flavors in sausage. TBA, L-, a-, and b-values were unaffected by SL level.     

Effect of water activity (aw) and irradiation on the shelf-life of fresh noodles

In this work, the effect of water activity (a_w), irradiation and their combination on the preservation of fresh noodles was studied. Microbial growth, pH and sensory characteristics were investigated during 16 days' storage time under 37 °C. The combination of glycerol (3%), propylene glycol (2%), compound phosphate (0.4%) and salt (3%) was proved to be the most effective group which could reduce a_w from 0.979 (control) to 0.900. Under this condition, the shelf-life of fresh noodles could be extended for more than 7 times. Moreover, a synergism between humectants and irradiation treatment was observed in relation to microorganism inhibition and shelf-life extension. For all the irradiated noodles, TPC (total plate count) did never exceed the selected deterioration threshold limit (10⁶ CFU/g) during the entire observation period. When the irradiation dose was 4 kGy or higher, scarcely any bacteria proliferation was observed. Noodle samples irradiated at 4 kGy showed the best pH and sensory stability as the storage time increased.

Industrial relevance

This paper presents an effective and low-cost method to prolong the shelf-life of fresh noodles, which can largely extend the store time of fresh noodles at room temperature, and does not produce any negative changes in sensory attributes. This method will be a new system for food preservation with lots of possible industrial applications. The results of this research also have implications for dumpling skins and other noodle types.     

Shelf Life of Shrimp (Penaeus merguiensis) Stored at Different Temperatures

The sensory, microbiological and biochemical changes were determined in shrimp (Penaeus merguiensis) stored at 0° to 35°C. Mean aerobic plate count of fresh shrimp, initially 5.0 × 10⁵ CFU/g, increased with time and temperature to 6.4 × 10⁹ CFU/g at 35°C after 24 hr. A total of 560 different bacteria were isolated and identified. In addition, the dominant organisms were tested for ability to reduce TMAO, produce indole and hydrolyze protein. The initial bacteria were 30% Gram + organisms but changed to predominantly Grampsychrotrophs at lower temperatures and to mesophiles at higher temperatures. Odor, texture and color qualities decreased; TMA, TVB, pH and Indole increased with time and temperature. Shelf life of shrimp ranged from 7 hr at 35°C to 13 days at 0°C.     

丁香油与月桂酸对金黄色葡萄球菌的协同抑制作用

该研究探讨了丁香油、百里香油、薄荷油等三种植物精油以及中链脂肪酸月桂酸对金黄色葡萄球菌的抑制作用,筛选出具有协同抑制作用的组合丁香油与月桂酸,测定协同组合对金黄色葡萄球菌生长、细胞膜通透性的影响,并将该组合制成抑菌保鲜液,应用于生鲜米粉保鲜。结果表明,丁香油、薄荷油、百里香油及月桂酸对金黄色葡萄球菌的最小抑菌浓度分别为2.00μg/mL、4.00μg/mL、7.50μg/mL以及9.00μg/mL,丁香油和月桂酸联合使用,在浓度为1/4 MIC丁香油+1/4 MIC月桂酸时具有协同抑菌效果,此时分级抑菌浓度系数为0.50。丁香油与月桂酸协同处理使金黄色葡萄球菌细胞膜损伤,增加通透性。抑菌保鲜液对生鲜米粉中的菌落总数、金黄色葡萄球菌均有抑制作用,对维持生鲜米粉品质具有积极影响。72 h贮藏期间,处理组初始菌落总数比对照组至少低1.50 lg CFU/g;金黄色葡萄球菌降低1.65 lg CFU/g;酸度值比对照组至少低0.8°T;感官评价得分均高于对照组。结果表明,丁香油与月桂酸协同组合制成抑菌保鲜液有可能成为生鲜米粉的可替代复合保鲜液。