Effect of Frozen Storage on the Quality of Frozen Foods—A Review

This paper reviews the quality changes that occur towards the food products during the frozen storage period.This research aims to determine the significant physical and chemical changes that had occurred onto the frozen foods.Indeed,refrigerated storage is the easiest way to preserve food within short handling time.Based on the observation,it was discovered that the kinetics reactions help to establish computer-aided quality,prediction models.In certain food products,the negative impact of temperature indicated the need for a thorough evaluation of the quality parameters of individual’s kinetics reaction.In general,a reasonable temperature to store food is-18°C for most frozen foods,and this will retain the quality of commercial storage.

Microbial profile of some ready-to-cook frozen food items sold in Dhaka city,Bangladesh

This study aimed to assess the microbiological quality of 159 animal-and plant-based ready-to-cook(RTC)frozen food items currently popular in Dhaka.Microbiological analyses were carried out to enumerate total aerobic counts of mesophilic bacteria,yeast and mold and to detect some common foodborne pathogens according to standard microbiological criteria.Higher microbial loads in all animal-based food types,other than chicken strips were found.In contrast,plant-based items were relatively safe except paratha,dal-puri,rooti chapati,and aloo-puri.Several common pathogenic bacterial species were screened by analyzing their morphological,cultural,and biochemical characteristics.Escherichia coli was prevalent in most samples,while Salmonella species were least reported.A considerable number of samples exhibited enough microbial loads at infection or intoxication levels.

Cold-chain transportation in the frozen food industry may have caused a recurrence of COVID-19 cases in destination:Successful isolation of SARS-CoV-2 virus from the imported frozen cod package surface

Coronavirus disease 2019(COVID-19)pandemic has spread in 220 countries/regions towreak havoc to human beings around theworld.At present,the second wave of COVID-19 has begun in many European countries.The complete control of COVID-19 is very urgent.Although China quickly brought the virus under control,there have been eight sporadic outbreaks in China since then.Both in Xinfadi of Beijing and Dalian outbreak of COVID-19,environmental swab samples related to imported cold chain food were tested nucleic acid positive for SARS-CoV-2.In this outbreak in Qingdao,we directly isolated SARS-CoV-2 from the cod outer package's surface swab samples.This is the first time worldwide,SARS-CoV-2 were isolated from the imported frozen cod outer package's surface,which showed that imported frozen food industry could import SARS-CoV-2 virus.

Growth and survival of blue swimming crab (<i>Portunus pelagicus</i>) reared on frozen and artificial foods

Experiments were conducted to evaluate the efficacy of two frozen organism (with and without instant Nannochloropsis oculata and with and without instant encapsulated Spirulina) and artificial diet (with and without artificial encapsulated shrimp larvae feed) with live food as continues feed in the larval rearing of blue swimming crab, Portunus pelagicus. The larvae were conducted with six treatments and each treatment with three replications on newly one day hatched larvae in each replication. Results showed that these larvae fed with a combination diet of instant frozen N. oculata, Artemia nauplii and rotifer give a higher survival rate till 1st day juvenile crab compared to the treatment with instant encapsulated Spirulina and artificial diet (with artificial encapsulated shrimp larvae feed). One of experiments treated with encapsulated Spirulina recorded only 16 days for the zoea to reach the C1, one day earlier as compared to previous trials treated with and without instant frozen N. oculata. One of the experiments treated with artificial encapsulated shrimp larvae feed recorded 18 days for the zoea to reach the C1, 1 to 2 days longer as compared to all the previous trials earlier. Food type influenced survival, development, and metamorphosis to megalopa and 1st day juvenile crab of P. pelagicus zoea larvae. Our findings illustrate that the best survival, the most rapid development and the highest number of 1st day juvenile crabs were obtained from larvae fed with a combination diet of frozen N. oculata, Artemia nauplii and rotifer from hatching till the 1st day juvenile crab.

Probiotics viability in frozen food products

Improving gastrointestinal flora with probiotics is a promising method of treating and preventing many diseases.However,in food industry,introduction of probiotics is limited by the shelf life of products,as well as by the reduction of bacterial viability during storage.Thus,introduction of probiotics into foods to be frozen is a promising method to extend the shelf life of probiotic products.However,the storage of living cells in frozen products involves their damage during freezing and subsequent storage at temperatures below 0°C.Therefore,some technological solutions are required to protect probiotics during storage at sub-zero.Today,encapsulation,addition of cryoprotectants and prebiotics,as well as adaptation of microorganisms are widely used techniques of protecting probiotics.The combination of various protection methods is a promising way to improve the viability of probiotics during storage.Studies aimed at investigating various combinations of hurdle methods and their effect on bacterial survival are of great interest.This review compiles the most common methods of preserving probiotics in frozen foods,describing their effects,variety of approaches,and effectiveness.The main mechanisms of bacterial cell damage by freezing are described.Further trends in probiotic protection in frozen foods are also discussed.

Prevalence and antimicrobial resistance of Salmonella spp.in raw retail frozen imported freshwater fish to Eastern Province of Saudi Arabia

Objective:To determine the proportion of imported frozen fish contaminated with Salmonella among retail food stores and supermarkets in the Eastern Province of Saudi Arabia.Methods:A total of 223 frozen freshwater fish purchased from different supermarkets and grocery stores were analyzed for the presence of foodborne pathogen Salmonella.The isolation of Salmonella was determined and confirmed by using the methods of US Food and Drug Administration's Bacteriological Analytical Manual.CHROMagar Salmonella plus,biochemical tests and API 20E strips.Antimicrobial susceptibilities of Salmonella isolates were determined by the disk diffusion method on Muller-Hinton agar,as described by Kirby-Bauer.in accordance with the guidelines of the Clinical and Laboratory Standards Institute.Results:Out of the total 223 fish samples(20 of catfish,18 of carfu,20 of mirgal,25 of milkfish,35 of mackerel,75 of tilapia,and 30 of rohu),89(39.9%)were tested positive for Salmonella.The prevalence of positive samples were reported for the freshwater fish of pangas(60.0%,n=12),carfu(27.7%,n=5),mirgal(35.0%,n=7),milkfish(52.0%,n=13),mackerel(31.4%,n=11),tilapia imported from Thailand(64.0%,n=16),tilapia imported from India(28.0%,n=14),rohu imported from Thailand(26.6%,n=4)and rohu imported from Myanmar(46.6%,n=7).A total of 140 isolates of Salmonella spp.were yielded from at least seven different types of frozen freshwater fish imported from 5 different countries and were tested for their susceptibility to 16 selected antimicrobial agents.The highest antibiotic resistance was observed to tetracycline(90.71%)followed by ampicillin(70%)and amoxicillin-clavulanic acid(45%).Conclusions:The obtained results of this study shows that these raw retail imported frozen freshwater fish are contaminated with potentially pathogenic Salmonella spp.And the study recommend and suggest that there is a need for adequate consumer measures.

冷冻食品中冰晶检测技术的研究进展

冷冻加工过程中冰晶的形成与生长会对食品的品质造成极大影响。快速而准确地检测冷冻食品中的冰晶,以有效控制和调节其成核和生长,具有重要的科学价值。该文在总结冰结晶过程及其对冷冻食品品质影响的基础上,概述了近年来冷冻食品中冰晶检测技术的相关研究进展,并对未来发展趋势和面临的挑战进行了分析和展望。其中,基于光学、电学、磁学、声学等物理方法的新型冰晶检测技术具有无损在线检测的潜力,且可以结合人工智能技术,极大地提高冰晶检测的准确性和效率,是未来该领域的重要发展趋势。

不同剂量辐照处理对冷冻畜禽肉类品质的影响

目的:研究不同剂量辐照对冷冻畜禽肉类食品品质的影响,确定其辐射耐受剂量,为冷链食品的辐照消毒应用提供参数支持。方法:以冷冻羊瘦肉、牛瘦肉、猪瘦肉、鸭胸、鸡胸、猪肥肉及羊肥肉共7种肉类为研究对象,给予2kGy、4kGy、6kGy和7kGy的γ射线辐照处理,严格按照国家标准对不同种类肉类色泽、气味、蛋白质分解、脂肪氧化情况进行检测分析,探索辐照对畜禽肉类品质的影响。结果:2~7 kGy的γ射线对冷冻畜禽肉的色泽、气味无明显影响;与脂肪氧化相关的指标过氧化值、酸价均低于检测下限,挥发性盐基氮的含量均在国家标准的限定范围内。结论:2~7kGy的γ射线辐照后不会使畜禽肉品质发生明显改变。

冷冻处理对食品组分及品质的影响

冷冻通过抑制微生物生长和理化性质变化来维持食品品质,延长食品保质期。传统的冷冻处理方法,虽具有延长食品保质期的作用,但仍不可避免地引起食品不良的品质变化。冰晶的形成和蛋白质变性是导致食品品质劣变的主要原因。近几年,为缓解食品在冷冻贮藏过程中品质的下降,通过研究新技术抑制冰晶生长,添加冷冻保护剂增强各食品组分间作用和改变食品的环境条件来延缓食品在冷冻贮藏过程中的品质变化。本文针冷冻对蛋白质基食品贮藏过程中水分、蛋白质、脂肪等组分的影响。重点阐述冷冻引起冰晶的形成和重结晶造成的机械损伤。蛋白质冷冻变性和蛋白质的其它变化对蛋白质功能特性的影响。蛋白质和脂肪氧化对食品品质的影响和相互作用关系以及对蛋白质-蛋白质、蛋白质-脂肪和蛋白质-糖类等相互作用的改变对食品品质带来的影响,并对冷冻技术和冷冻保护剂等进行综述,为新型冷冻技术和工艺的开发提供理论依撑。

罗望子多糖对冰重结晶、生长习性和量热行为的影响

为系统考察罗望子多糖对冰晶生长的抑制效应,采用“蔗糖三明治”冰重结晶试验、Lifshitz-Slyozov-Wagner(LSW)理论模型、动态冰晶修饰试验和差示扫描量热法研究该多糖溶液的冰重结晶动力学、冰晶生长习性和量热行为。结果表明,罗望子多糖在溶液中呈浓度依赖性构象转变,该多糖具有显著的冰重结晶抑制活性,其中添加0.25%(质量分数)的多糖可以使冰晶生长速率降低近10倍。罗望子多糖具有较弱的冰晶形貌修饰活性,暗示其与冰晶表面可能具有较弱的相互作用。此外,罗望子多糖具有一定的冰点抑制活性而对融点没有显著影响。值得注意的是,当多糖浓度超过一定值时,冰重结晶抑制活性和冰点抑制活性略有降低,推测罗望子多糖基于“界面效应”抑制冰晶生长。研究结果表明罗望子多糖具有作为新型天然冷冻食品抑冰剂的潜力,也为理解天然多糖的防冻机理提供了新的思路。

食品多糖对冷冻面团特性的影响及作用机理研究进展

食品多糖因来源广泛,结构多样,具有保水性、流变性、乳化性和稳定性等多种理化性质。在面团系统中,食品多糖不仅能抑制面团在冷冻期间发生的水分流失、面筋结构损伤及酵母发酵力变差等问题,还能进一步缓解成品硬度增大、体积变小及感官风味变差的问题。该综述总结了食品多糖的来源、分类和结构特征,概述了不同食品多糖对冷冻面团水分、流变、发酵等特性和馒头品质的影响及作用机理,并针对目前的研究进展做出展望,以期为食品多糖在冷冻面团工业中的应用提供参考。

液相色谱-串联质谱法快速检测速冻调制食品中7种甜味剂与防腐剂含量

目的建立液相色谱-串联质谱法(liquid chromatography-tandem mass spectroscopy,LC-MS/MS)快速检测速冻调制食品中7种甜味剂与防腐剂的分析方法。方法采用Phenomenex Kinetex F5色谱柱(50 mm×2.1 mm,2.6μm),以0.05%甲酸-10 mmol/L乙酸铵和乙腈进行梯度洗脱,电喷雾离子源(electrospray ionization,ESI)负离子模式、多反应监测(multiple reaction monitoring,MRM)模式进行测定。结果在0.01~0.20 mg/kg质量浓度范围内,目标物的线性关系良好,相关系数均大于0.99,方法检出限(S/N=3)为0.01~0.10 mg/kg;在不同添加浓度(1.0、2.0、10.0 mg/kg)下,其回收率为81.2%~105.3%、相对标准偏差均不大于10%。结论该方法具有操作简便、快速、准确、灵敏等优点,可满足速冻调制食品中7种甜味剂与防腐剂的定性定量分析,为速冻调制食品中防腐剂与甜味剂的快速筛查和风险分析奠定基础。

速冻食品生产中的冷链管理及质量控制研究

合理的温度控制、包装密封性、运输环节的管理和人员培训等因素对速冻食品质量具有重要影响。因此,本文分析了冷链管理在速冻食品生产中的应用,提出了相关优化措施,旨在降低速冻食品在生产与运输过程中的质量损失,以供参考。

浅谈变性淀粉在冷冻型食品中的应用现状

随着现代生活节奏的加快,冷冻型食品因其便捷性和长期储存的特性而广受欢迎。变性淀粉作为一类重要的食品添加剂,在冷冻食品的加工和质量提升方面起重要作用。本文综述了变性淀粉的特性及其在冷冻型食品中的应用,利用变性淀粉可较好地改善冷冻型食品尤其是米面制品表皮易开裂、表面发暗、蒸制塌陷、口感黏连等品质问题,这对于节约成本、扩大消费和促进食品业发展具有积极意义。

冷冻肉制品食品安全风险分析及控制措施

冷冻肉制品是指畜肉宰杀后,经预冷、排酸、急冻,继而在-18℃以下储存,深层肉温在-6℃以下的肉品,可有效降低肉类中微生物的活性,减缓化学反应速度,从而延长肉类的保质期。然而,受到饲喂环境、兽药残留、生产加工、包装、贮藏及运输等因素的影响,冷冻肉制品存在一定的食品安全风险。基于此,本文系统分析了冷冻肉制品可能存在的食品安全风险,并提出针对性的控制措施,旨在确保冷冻肉制品的质量和安全,为消费者提供健康、可靠的食品。

速冻油炸食品过氧化值超标原因及控制措施分析

随着速冻食品市场的快速发展,油炸工艺作为提升食品风味与口感的重要手段,其安全性问题日益受到关注。其中,过氧化值是衡量油脂氧化程度的关键指标,对速冻油炸食品的质量安全影响较大。基于此,本文介绍了过氧化值超标的危害及其主要检测方法,简述了影响过氧化值检测结果的主要因素,分析了导致速冻油炸食品过氧化值超标的主要原因,并针对性提出控制过氧化值的措施,以供参考。

基于超声波的食品解冻技术研究

以牛肉为样品 ,对超声波解冻进行了研究 ,分析了在食品不超温情况下超声波频率、强度和加载方向对可解冻厚度的影响。以 80 0 k Hz超声波进行实验 ,理论计算值与实验结果总体上是一致的 。

速冻食品中沙门氏菌和金黄色葡萄球菌多重PCR检测方法的建立与应用

为实现速冻食品中沙门氏菌(Salmonella spp.)和金黄色葡萄球菌(Staphylococcus aureus)的多重聚合酶链式反应(PCR)检测,首先优化多重PCR扩增的反应条件,比较基因组DNA提取方法,结果表明:退火温度采用60℃、各引物浓度200nmol/L及扩增循环35次,本多重PCR检测技术可以有效地将沙门氏菌和金黄色葡萄球菌同时检出,检测特异性为100%。3种DNA提取方法中试剂盒法纯度最高,检出限分别是31、26DNA copies/reaction。经过在人工污染致病菌的速冻水饺中应用试验后,该多重PCR方法经过4h的增菌培养即可从速冻水饺中同时检测出起始菌落数低至100CFU/g的沙门氏菌和金黄色葡萄球菌。

国内外冷冻冷藏预制食品产业现状及发展前景

由于生活节奏、家庭人口规模、经济条件等的变化,预制食品在食品体系中的重要性日益增长。主要就国内外冷冻冷藏预制食品产业的现状进行简单阐述,总结冷冻冷藏预制食品发展的客观原因,指出其必将在我国迎来蓬勃发展。

食品冷冻理论和技术的进展

冷冻贮藏对食品保藏和运输具有重要意义,冷冻食品加工行业发展势头良好,与食品冷冻相关的理论与技术也有长足的进展。本文介绍了与食品冷冻过程相关的传递、玻璃化转变和冰结晶理论的现状和进展,指出由食品物料及其在冷冻过程变化的特殊性所引起的建立系统的食品冷冻理论的复杂性;综述了超声强化冷冻、高压冷冻、冷冻蛋白技术、CAS冻结系统和冰温技术的简要原理,及其在食品行业的应用进展。