冷藏中温度波动对牛肉品质的影响

温度波动在冷链运输中不可避免,是造成食品品质下降的最主要原因。本研究以速冻牛肉为原料,在空白组(-18℃)和温度波动组B(-18℃—-17℃)、C(-18℃—-13℃)、D(-18℃—-8℃)四个不同条件下,对牛肉的p H、色差、质地剖面分析(TPA)指标(硬度、弹性、凝聚性、胶性、咀嚼性)和显微结构进行测定。结果表明:随着温度波动幅度的增加,牛肉的品质显著下降。     

取向纳米改性包装材料阻隔性数学模型

取向纳米改性是提高包装材料阻隔性的一种有效的绿色化方法。本文阐述了蒙脱土的结构性能、纳米化的方法及其改性包装材料阻隔性的原理,重点介绍了多种预测取向纳米蒙脱土改性聚合物渗透性的模型,包括模型的构建条件、影响因素、数学建模和运用范围。讨论并比较了各种模型优缺点及与实验结果的符合程度,为取向纳米改性包装材料阻隔性的预测提供了理论依据。     

Microwave Assisted Thawing of Model Frozen Foods Using Feed-back Temperature Control and Surface Cooling

An apparatus was developed that combined microwave energy and cold air with different ambient temperatures to reduce thawing time and avoid run-away heating during microwave assisted thawing. Effects of microwave power level, sample thickness and surface air temperature on thawing time were investigated. The microwave power was cycled on and off using two temperature control schemes to maintain a predetermined temperature gradient based on hot and cold points. Thawing time was reduced by as much as a factor of seven compared to convective thawing at ambient temperature when appropriate conditions were used.     

Effect of Handling and Packaging on the Quality of Frozen Whitefish

Individually frozen, scaled whitefish (Coregonus clupeaformis) rapidly developed oxidative off-flavors when stored without packaging at ?12°C, but both vacuum-packaging in barrier films and ice-glazing significantly suppressed the development of oxidized flavors through 24 wk of storage. Removal of scales prior to freezing significantly enhanced the development of oxidized flavors over unscaled whitefish when both were held unprotected at ?12°C. Loose-packaging of individual, well-washed whitefish in closed polyethylene pouches significantly improved oxidative stability compared to those stored unprotected. However, vacuum, barrier-film packaging gave significantly better protection than polyethylene at both ?12°C and ?25°C through 24 wk and 72 wk, respectively.     

食品包装油墨迁移研究进展

食品安全越来越受到广泛关注,包装材料中油墨引起的食品质量问题频频发生,本文论述国内外包装油墨安全相关的法规及要求,总结国内外油墨迁移研究现状,为今后的食品包装油墨安全提供法律依据和实验指导。     

可生物降解包装材料的性能及应用研究

0引言可生物降解聚合物分为合成生物降解聚合物(如某些聚酯)和天然生物降解聚合物(如淀粉)。现代可生物降解包装材料可以通过     

可生物降解包装材料的性能和应用研究(英文)

目前,可生物降解包装材料已经成为替代传统合成材料的重要环保型材料。早期,已有研究人员将可生物降解聚合物应用于包装材料领域。近年来,随着环境问题,原油储量压力的加剧和普通消费者的偏爱,生物基及可生物降解聚合物得到进一步发展。本文介绍了可生物降解包装材料的发展过程,重点综述了材料的性能和应用。     

Reference Materials for Calibrating Probes Used for Measuring Thermal Conductivity of Frozen Foods

Reference materials which contained either 8% or 10% bentonite pastes and very fine pure copper powder (300 mesh, 30–.55%), provided thermal conductivities ranging from 0.9 to 1.9 W/mK. These materials were used to calibrate probes for measuring thermal conductivity of frozen food materials. Thermal conductivity values measured by the steady-state (parallel plate) method, the unsteady-state heat transfer (heating curve) method, and the probe method agreed within 5%. Although experimental density and heat capacity data of copper-filled bentonite pastes agreed with a mass average value of component properties, measured thermal conductivity values were much lower than the volume fraction average values.     

冻结速率对凡纳滨对虾虾仁贮藏特性的影响

本文以凡纳滨对虾（Penaeusvannamei）虾仁为原料,分别采用-80℃和．20℃两种冻结条件对虾仁进行冻结处理,分析冷冻速率对凡纳滨对虾虾仁贮藏过程中理化、鲜度及色泽特性的影响,明确冻结速率对虾仁解冻后的质量变化特征的影响规律。总体来讲,冻藏过程中虾仁质量变化趋势基本一致,随着冻藏时间的延长,虾肉解冻损失率增加,鲜度降低,pH呈下降后上升的趋势,TVB-N值上升,产品的亮度指标L＊升高。冻结速率对虾仁的贮藏特性影响差异显著,冻藏6d后冻结速率对虾仁解冻损失率、鲜度指标影响出现分化,-80℃速冻处理可明显改善虾仁的解冻失水,保证虾仁鲜度。20d后,pH值、TVB-N值变L‘值变化情况也表明-80℃速冻在一定程度上可以减轻虾仁贮藏过程中的质量劣化程度。     

冻结食品的解冻技术

就冻结食品的解冻技术进行了综述。对各种解冻方法的解冻原理及其在食品中的应用做了论述和分析,着重介绍了微波解冻、超声波解冻和高静水压解冻技术。     

日本冷冻食品生产与消费近况

简要介绍了日本的主要冷冻食品种类,介绍了日本全国冷冻食品的年产量、不同类别冷冻食品的年产量和冷冻食品年消费量的历年变化情况.     

陶瓷、玻璃食品包装中化学物质的检测和迁移研究进展

陶瓷和玻璃食品包装中的化学物质迁移到食品中危害消费者的健康,为此国内外建立了相关的法规来确保陶瓷和玻璃包装使用的安全性。本文对陶瓷和玻璃食品包装中的有害金属元素、欧盟和我国相关法规中的限量标准、与陶瓷接触的食品样品的消解方法、陶瓷和玻璃食品包装中有害金属元素的检测方法和迁移研究予以综述。     

超声辅助冷冻技术的作用机制及其对食品品质影响的研究进展

冷冻是一种重要的食品保藏技术,但冻结也会引起食品品质的变化。作为一项高新加工技术,超声辅助冷 冻技术可以加快冷冻速率,减小冰晶的尺寸,进而改善冷冻食品的品质。本文主要论述了超声辅助冷冻技术的作用 机制及对冰结晶形成的影响,同时综述了超声辅助冷冻技术对食品品质的影响及食品冷冻中常用的工艺参数。最 后,展望了超声辅助冷冻技术的发展方向,为超声辅助冷冻技术在食品中的应用提供理论支持。     

软包装材料摩擦性能实验参数研究

在不同实验条件下对PE膜、PP膜、PET膜及牛奶黑白膜4种软包装材料的摩擦系数进行了一系列测定,分别研究了不同的摩擦副组成、试验温度、静接触时间、滑动速度和法向载荷等实验参数对软包装材料摩擦性能的影响,并通过方差分析研究了实验参数对摩擦系数的影响程度。实验结果表明:不同摩擦副组成的摩擦系数有显著差异;试验温度和静接触时间都对摩擦系数影响显著(P<0.05);试验速度和法向载荷对摩擦系数影响不显著(P>0.05)。     

不同贮藏温度对速冻羊肉品质影响的实验研究

为研究时间对不同贮藏温度下速冻羊肉品质的影响,采用了菌落总数、挥发性盐基氮、pH、酸价及水分含量为指标,对速冻羊肉在-15、-20、-25℃三种不同温度冻藏温度和5、15、25℃三种不同冷藏温度下中的上述指标的变化进行了研究。实验结果显示,菌落总数、挥发性盐基氮、pH、酸价随贮藏时间的延长而增加,随贮藏温度的增加而上升。与冷藏温度下贮藏的速冻羊肉相比,冻藏能更好保持速冻羊肉的品质,减缓细菌的生长,减少水分的散失,能更久地保持其品质与延长其货架期。     

温度波动对贮藏猕猴桃品质劣变的影响

以“红阳”猕猴桃为试材,采用低温贮藏方式,分别设定3 个不同温度波动区间处理：对照猕猴桃在2 ℃贮藏,处理组温度波动范围为3 ℃（2～5 ℃）和5 ℃（2～7 ℃）下循环处理72 h（12 h 交替运行）,处理后贮藏于2 ℃条件下,通过测定猕猴桃的失重率、果实硬度、可滴定酸、可溶性固形物含量等指标,探究温度波动对猕猴桃品质变化的影响。结果表明：在猕猴桃贮藏过程中,温度波动处理提高了多酚氧化酶活性并使过氧化物酶活性高峰提前。温度波动处理对猕猴桃在贮藏前期的品质有较大影响,加快了猕猴桃硬度和维生素C 的下降,提高可溶性固形物含量和相对电导率,加剧透明化,引起猕猴桃各方面品质参数的衰变,致使整体走向衰败现象。贮藏过程中温度波动越大,对猕猴桃的品质参数变化影响越大,不利于猕猴桃的贮藏和保鲜。综上,温度波动处理对猕猴桃贮藏品质及生理代谢影响明显,降低果实抗氧化性以及加快细胞膜降解,加速了猕猴桃整体品质下降。     

Effect of Packaging on Color and Physical Characteristics of Ground Pork in Long-term Frozen Storage

Ground pork, 30% fat, was packaged in 454g units in Cryovac bags heat scaled under vacuum (V), Saran Wrap? (S), aluminum foil (A), Saran? overwrapped with aluminum foil (SA), and polyvinyl chloride (PVC) and frozen 13, 26, or 39 wk at ? 17°C. TBA values increased over time regardless of packaging. Those materials that excluded oxygen delayed lipid oxidation longest. Red color (CIE a* value and % reflectance difference at 630 and 580 nm) decreased over time; this was greater on exterior than interior of the meat block. Materials that excluded oxygen prevented loss of red color during the first 26 wk storage. Changes in redness and TBA appeared unrelated to pH. Changes in L* and b* values did not appear related to packaging treatment or storage time.     

Effect of Packaging on Physical and Sensory Characteristics of Ground Pork in Long-term Frozen Storage

Effects of packaging materials on water-holding capacity (WHC), thaw and cook losses, TBA value, moisture and fat content, and sensory characteristics of ground pork held in frozen storage for 13, 26, or 39 wk were examined. Moisture and juiciness decreased and total losses (thaw + cook) increased over time regardless of packaging. WHC decreased most in PVC-packaged pork (fresh = 0.53, 39 wk = 0.17) and least for vacuum-packaged pork (39 wk = 0.25). After 39 wk TBA values were highest for PVC-packaged (2.98) and lowest for vacuum-packaged pork (1.16). Rancid and sour odors and flavors followed similar trends.     

冻藏对高风险食品中微生物的影响

选择沙拉、生食水产品、凉拌菜三种高风险食品,比较冻藏前后菌落总数和大肠菌群数量差异。结果显示:三种样品在冻藏前后微生物数量均有不同的变化,其中,沙拉和凉拌菜样品菌落总数变化不明显,生食水产品中菌落总数有所增加,但并无显著性变化;三种样品大肠菌群均有明显的变化,其中,沙拉和凉拌菜均有显著性降低(p<0.05),而生食水产品有明显增加,但并不显著。