Overall Quality Throughout Shelf Life of Minimally Fresh Processed Fennel

ABSTRACT: The keeping quality of minimally fresh processed fennel up to 14 d at 0 °C under modified atmosphere packaging was studied. Samples of 1 cm³ diced fennel washed for 1 min with chlorinated (100 mg/L) water were placed in 35 μm oriented polypropylene (PP) bags or in PP baskets heat-sealed with unperforated or perforated (control) PP film. Changes in respiratory activity, ethylene emission, color, sugars content, chemical parameters, browning, decay, microbial growth, and sensory attributes were monitored. Respiratory activity in diced fennel was 1.5–fold higher than that for whole bulbs, and slight differences in ethylene emission between both whole and fresh processed fennel were found. A gas composition within both kinds of unperforated packages of about 11 to 13 kPa O₂ and 9 to 12 kPa CO₂ was reached. At the end of storage of fennel dices under this atmosphere, total plate counts were lower than legal limit for safe consumption. At any moment, neither physiological disorders nor decay developed. Although after 14 d a slight browning on the dices surface appeared, levels of sensorial attributes higher than acceptable for commercial purposes were reached.     

Cutting Blade Sharpness Affects Appearance and Other Quality Attributes of Fresh-cut Cantaloupe Melon

ABSTRACT: Cantaloupe melon pieces (1.8 cm dia × 3.5 to 4.0 cm cylinders) were prepared using stainless steel borers with sharp or blunt blades, and stored for 12 d in air at 5 °C. Pieces prepared with the sharp borer maintained marketable visual quality for at least 6 d, while those prepared with the blunt borer were unacceptable by d 6 due to surface translucency and color changes. Borer sharpness did not affect changes in decay, firmness, sugar content, or aroma, but blunt-cut pieces had increased ethanol concentrations, off-odor scores, and electrolyte leakage compared to sharp-cut pieces. Respiration rates at 5 °C were similar for both cutting treatments, but ethylene production rates were sometimes higher in pieces cut with the blunt blade.     

Microbial, Enzymatic, and Chemical Changes During Storage of Fresh and Processed Orange Juice

Microbial, enzymatic, and chemical comparisons were made on orange juice stored at 4°C without pasteurization, with light pasteurization (66°C, 10 sec) directed at vegetative microorganisms, and with full pasteurization (90°C, 60 sec) directed at the heat stable isozyme of pectinesterase. Effects of oxygen-barrier and nonbarrier packaging were also examined. Oxygen-barrier packaging did not benefit unpasteurized juice. However, lightly and fully pasteurized juices in barrier cartons exhibited lower microbial counts, greater ascorbic acid retention, and apparent slowing of cloud loss by the third week of storage. During the first 22 days storage, microbial, cloud, sugar, and ascorbic acid values for lightly pasteurized juice were similar to those of juice receiving full pasteurization.     

Cultivar Effects on Quality of Fresh Cut Apple Slices from 1-Methylcyclopropene (1-MCP)-Treated Apple Fruit

ABSTRACT: The effects of 1 -methylcyclopropene (1 -MCP) treatment of whole fruit on the subsequent quality and shelf-life of fresh-cut apple slices have been investigated. 'Delicious,' Empire, 'Idared', Law Rome, and 'Mutsu' apples were treated at 0.5°C with 1 μL/L of 1 -MCP for 24 h and stored in air 1 and 4 mo before being used for preparation of slices. 1-MCP reduced internal ethylene concentrations and maintained firmness of the whole fruit in'Delicious,' Empire, and 'Idared', but not consistently for 'Law Rome' and 'Mutsu.' Slices prepared from fruit of cultivars that responded to 1 -MCP had lower ethylene production rates and were firmer than those from untreated fruits. However, 1-MCP treatment did not consistently affect the extent of browning or aroma volatile concentrations. In cultivars in which treatment of apples with 1-MCP at harvest maintained the original fresh quality of intact fruit by suppressing ethylene production, fruit were firmer, and thus a superior fresh- cut product with an extended shelf-life potential was obtained. However, in general, slices prepared from untreated and 1-MCP-treated fruit deteriorated at similar rates.     

热处理对鲜切哈密瓜品质及其微生物的影响

为研究热处理对鲜切哈密瓜品质及其微生物的影响,分别采用75、85、95℃热水对鲜切哈密瓜烫漂30、60s,在冷藏(5℃)过程中每2d测定鲜切哈密瓜的菌落总数、色泽、还原型抗坏血酸、总酸、可溶性固形物、相对电导率和渗汁率。结果表明:在热处理当天,95℃、60s处理杀菌的效果最好,菌落总数为28CFU/g,而对照的菌落总数为1.3×103CFU/g,两者相差约46倍;第10天时,对照组的菌落总数为1.8×108CFU/g,而含量最低的95℃、30s处理的鲜切哈密瓜的菌落总数为2.4×105CFU/g,两者相差750倍;在处理当天和贮存过程中,热处理对还原型抗坏血酸含量、总酸含量、可溶性固形物含量和渗汁率有一定影响,但对色泽几乎没有影响。     

贮藏温度对鲜枸杞生理指标和营养品质的影响

为研究鲜枸杞在不同贮藏温度下的品质损耗规律,将新鲜采收的枸杞果实分别放在4℃和-4℃冷库贮藏21 d,测定并分析生理指标和营养品质的变化。结果表明:-4℃贮藏显著下调鲜枸杞的呼吸速率(呼吸峰值比4℃下调37%)和乙烯产生速率,延缓鲜枸杞硬度下降,并提高商品果率,贮藏末期硬度和商品果率分别比4℃提高21.54%和10.95%;同时,-4℃贮藏的鲜枸杞可溶性固形物、可滴定酸、游离氨基酸和类胡萝卜素含量显著高于4℃,说明鲜枸杞在-4℃贮藏21 d仍保持较好的营养品质。     

食品原料安全与初加工食品质量安全控制——以新鲜蔬菜的质量控制为例

新鲜蔬菜富含多种维生素与纤维素等对人体健康有益的成分,是健康膳食的主要成分之一。人们对蔬菜的需求和消费量在近10 年中持续增高。新鲜蔬菜以其易腐烂的生物特性,及作为原产品或者初加工产品的鲜食特性,在消费中存在着化学、物理和微生物安全风险,是产生食源性疾病的主要源头之一。由于新鲜蔬菜的质量安全风险存在于供应链的各个环节,因此控制蔬菜的安全质量措施要贯穿整个供应链。基于食品供应链的食品安全管理体系（Food Safety Management System,FSMS）的实施非常重要。在蔬菜供应链的各阶段安全控制中,各种安全管理控制体系需要应用于相应的不同阶段。     

整粒小麦加工全麦脆片前后营养成分的变化

为了最大程度保留小麦的营养并赋予最终产品良好的口感,直接以整粒小麦为原料,采用浸泡蒸煮、挤压膨化、微波真空干燥等技术制备了全麦脆片,对加工前后小麦主要营养成分的变化进行了研究。结果表明:经过挤压和微波真空干燥后,淀粉少量降解,且达到完全糊化,其水溶性和吸水性指数增加;蛋白质质量分数略有上升,游离氨基酸质量分数变化不大,蛋白质体外消化率从69.31%增加到76.55%;脂肪质量分数变化不大,饱和脂肪酸质量分数从36.71%增加到56.78%,脂肪酸值降低;总膳食纤维质量分数变化不大,可溶性膳食纤维从2.06%增加到2.64%;总酚质量分数增加了2.6倍。     

Maintaining Quality of Fresh-cut Tomato Slices through Modified Atmosphere Packaging and Low Temperature Storage

ABSTRACT: Quality of fresh-cut tomato slices was compared during cold storage under various modified atmosphere packaging conditions. Chilling injury of slices in containers sealed with Film A was higher than with Film B; these films had oxygen transmission rates of 87.4 and 60.0 ml · h^-1· m^-2· atm^-1 at 5 °C and 99% RH, respectively. While slices in containers with an initial atmospheric composition of air, 4% CO₂+ 1 or 20% O₂, 8% CO₂+ 1 or 20% O₂, or 12% CO₂+ 20% O₂ showed fungal growth, slices in containers with 12% CO₂+ 1% O₂ did not. Low ethylene in containers enhanced chilling injury. Modified atmosphere packaging provided good quality tomato slices with a shelf life of 2 w or more at 5 °C.     

Ethylene Absorbent to Maintain Quality of Lightly Processed Fruits and Vegetables

Ethylene had an undesirable effect on the quality of kiwifruits, bananas, broccoli, and spinach leaves that were prepared and stored as lightly processed products. A 2.or 20 ppm ethylene treatment hastened the softening of the pulp of kiwifruits and bananas held at 20°C. Use of charcoal with palladium chloride, as ethylene absorbent, prevented the accumulation of the ethylene and was effective in reducing the rate of softening in kiwifruits and bananas and of chlorophyll loss in spinach leaves, but not in broccoli.     

Physiology and Microbiological Quality of Fresh-cut Mango Cubes as Affected by High-O2 Controlled Atmospheres

Preliminary study showed that among 40‐ to 100‐kPa O₂ atmospheres, 60‐kPa O₂ reduced the respiration of fresh‐cut ‘Carabao’ mango cubes the most when held at 5 °C or 13 °C for 42 h. Therefore, the effects of 60‐kPa O₂ on the physiology and microbial quality of fresh‐cut ‘Carabao’ and ‘Nam Dokmai’ mango cubes were determined and compared with those held in air. The high‐O₂ atmosphere reduced the respiration rate of ‘Carabao’ mango cubes stored at 5 °C but stimulated the rate after 2 d of storage at 13 °C. Browning of ‘Carabao’ cubes was accelerated by 60‐kPa O₂ at 13 °C. With ‘Nam Dokmai’ cubes, the high O₂ had no effect on respiration rate, browning, and incidence of water‐soaked appearance at 5 °C and 13 °C. The high O₂ did not affect texture or ascorbic acid content of ‘Carabao’ and ‘Nam Dokmai’ mango cubes at either temperature. Counts of lactic acid bacteria and molds were below the detection level (2.4 log colony‐forming units [CFU]/g) during storage at both temperatures. However, 60‐kPa O₂ stimulated the growth of mesophilic aerobic bacteria on ‘Carabao’ cubes and yeasts of ‘Nam Dokmai’ cubes at 13 °C. The increased microbial count may have been due to the higher pH of cubes stored in 60‐kPa O₂ at 13 °C than at 5 °C or in air. Within ‘Nam Dokmai’ mango cubes, the predominant genera in mesophilic aerobic bacteria were Enterobacter, Klebsiella, and Pantoea and in the yeasts were Candida, Cryptococcus, and Rhodotorula. These results indicate that 60‐kPa O₂ is not desirable for mango cubes when held at 13 °C.     

热处理条件筛选及其提高鲜切芋头贮藏品质的生理机制

为延长鲜切芋头贮藏期,本文研究热处理温度和时长对鲜切芋头贮藏品质的影响,并探究热处理控制鲜切芋头褐变的生理机理。结果表明,38、60和100 ℃的热处理均能降低鲜切芋头失重率、延缓硬度下降、抑制褐变,表明热处理能提高鲜切芋头的贮藏品质。60 ℃热处理效果最好,且60 ℃热处理1 min的保鲜效果要好于同温度下30 s和3 min的热处理效果。热处理降低了鲜切芋头总酚含量,抑制了苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)和多酚氧化酶(PPO)活性,延缓了鲜切芋头的酶促褐变。     

Viscoelastic Behavior of Melon Tissue as Influenced by Blanching and Osmotic Dehydration

ABSTRACT: Viscoelastic properties of melon tissue exposed to steam blanching and osmotic dehydration (atmospheric or under vacuum) in glucose aqueous solutions were analyzed in a dynamic rheometer using oscillatory shear and creep tests. The storage modulus (G') greatly exceeded the viscous modulus (G') for raw and treated melon tissues, but the elastic component was partially lost because of processing. Blanching caused less than a 1 -fold decrease in G', whereas osmotic dehydration resulted in approximately a 3-fold decrease in G'relative to the untreated melon. Both moduli showed a weak dependence on frequency, with greater slope of the G'frequency lines for treated samples. A mechanical model, consisting of a spring in series with 2 Voigt elements and a dashpot element, properly predicted the creep compliance response for all melon samples. In general, overall compliance significantly increased by the treatments. The instantaneous elastic compliance and the viscoelastic compliances were the most sensitive viscoelastic parameters for distinguishing the differences in cell wall structure among osmotically dehydrated sample at atmospheric pressure and the tissues exposed to the other osmotic treatments. In contrast, G'modulus did not show an ability to evidence these structural differences because there were no significant differences in the G'values of osmotically dehydrated tissues at atmospheric pressure or in vacuum, with or without calcium addition.     

1-甲基环丙烯处理对鲜切西瓜生理代谢和品质的影响

系统比较仅在鲜切前或鲜切后用1-甲基环丙烯(1-MCP)处理和鲜切前后均采用1-MCP处理西瓜对鲜切西瓜呼吸强度、乙烯释放量、可溶性固形物、硬度和颜色等指标的影响。研究结果显示使用1mg/L的1-MCP处理鲜切后西瓜24h是一种最佳处理方式,该处理方式在7d的贮藏期内不仅有效降低鲜切西瓜呼吸速率和乙烯产生量,而且有效维持鲜切西瓜的硬度和颜色。     

5种苹果微粉的理化品质与行为特征

为了制备高品质的苹果纯粉,给苹果制粉加工和新产品开发提供理论支持,以国家苹果种质资源圃中常见的5个加工兼鲜食苹果品种(长富2号、寒富、黄元帅、国光、秦冠)为原料,采用中短波红外干燥联合普通粉碎技术制备苹果微粉,对苹果微粉的理化指标及加工过程中的行为特征进行测定与分析,采用主成分分析法对苹果微粉的品质评价指标进行简化。结果显示,在理化指标方面,色泽上寒富苹果微粉的亮度显著高于其他品种苹果微粉,秦冠苹果微粉的亮度最小;长富2号微粉的总酚含量最高;富士系苹果微粉的总糖含量最高。在行为特征方面,长富2号和寒富在高应力条件下的黏结性较小且在输送过程中表现较好。对测定的20项指标依据主成分解释总变量和碎石图,从中提取了反映原来变量90.38%信息的3个主成分,综合各项指标得出富士系苹果是制备高品质苹果微粉的优选品种。     

热处理对微加工茭白的质构与色泽的影响

研究了热水处理对茭白的嫩度、表皮色泽、叶绿素含量的影响 .结果表明 :38℃热水处理 1h可保持茭白的嫩度、抑制表皮中叶绿素的合成、抑制细胞质膜相对透性的增加 ,研究还表明茭白采后无呼吸高峰出现 .     

低乳糖脱脂鲜奶酪加工工艺

以脱脂乳为原料,研究发酵剂和乳糖酶的比例、发酵温度、后熟时间3个单因素对鲜奶酪乳糖水解率的影响。通过响应面试验得出乳糖水解率最高的方案。在此基础上,通过感官评定研究发酵时间、后熟温度、凝乳酶添加量、糖的添加量4个单因素对低乳糖脱脂鲜奶酪品质的影响;由正交试验得出低乳糖脱脂鲜奶酪的最佳加工工艺:发酵剂添加量2%,乳糖酶添加量2.9‰(体积分数),凝乳酶添加量0.016%,糖的添加量5%,发酵温度39℃,发酵时间6 h,后熟温度4℃,后熟时间28 min。鲜奶酪的乳糖水解率为90.95%,高于乳糖不耐受症对乳糖水解率为70%的要求。其脂肪含量低于2.5%,组织状态良好,乳清析出适量,酸甜适宜,为一种新型低乳糖低脂鲜奶酪,市场前景广阔。     

高压二氧化碳处理对鲜切哈密瓜微生物与品质的影响

本实验以哈密瓜为原料,优化了清洗工艺,研究了高压二氧化碳（high pressure carbon dioxide,HPCD） 处理对鲜切哈密瓜贮藏期间（4 ℃避光贮藏8 d）微生物（菌落总数、霉菌和酵母菌总数）、感官指标（质量损失 率、质构、感官评价）、品质指标（可溶性固形物含量、pH值、VC含量）、酶（多酚氧化酶（polyphenoloxidase, PPO）、过氧化物酶）活力的影响。本研究首先确定了强酸电解水清洗25 min为最佳清洗工艺,清洗后鲜切哈密 瓜的菌落总数下降了0.81（lg（CFU/g））。2.5、3.5、4.5 MPa处理8 min后的鲜切哈密瓜在贮藏期间微生物数量显 著增加,PPO活力上升,且在贮藏8 d时,质量、硬度和VC含量分别下降了16.45%～42.70%、30.38%～48.97%和 96.25%～96.73%。本研究为HPCD技术应用于鲜切哈密瓜加工提供了理论依据。     

BioSuee膜和硅酸盐对鲜杏采后果实转色的抑制作用

为了研究电商物流包装贮运期间BioSuee膜和硅酸盐材料对新疆鲜杏果实色泽转变速率的影响,以新疆小白杏、赛买提杏和李广杏为试材,分别采用PE膜(CK)、BioSuee膜(T1)和BioSuee膜结合微孔晶体硅酸盐保鲜剂(T2)进行商业化包装,在(10±1)℃条件下运输后,置于(25±1)℃的环境中贮藏,测定包装盒内O2...     

船上加工鱿鱼熟片的品质特性

目的:研究船上加工秘鲁鱿鱼熟片的品质特性,对比船上加工、岸上加工对秘鲁鱿鱼熟片品质特性的影响。方法:利用扫描电子显微镜及苏木精-伊红染色观察其微观结构变化;十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)分析蛋白组成变化情况;通过测定蛋白疏水性、巯基和羰基含量分析肌肉蛋白氧化变性程度;利用质构仪分析质构特性;检测鱼片中挥发性盐基氮(total volatile basic nitrogen,TVB-N)含量、甲醛含量及pH值,并对其进行感官评价。结果:SDS-PAGE结果显示船上加工秘鲁鱿鱼熟片与鱿鱼原料的蛋白条带基本吻合,没有明显的条带产生或消失,全质构分析发现两者在硬度和弹性指标方面不存在显著差异(P0.05);与岸上加工鱿鱼熟片相比,船上加工鱿鱼熟片肌原纤维结构破坏少,表面疏水性低,溴酚蓝结合量为25.22μg,蛋白质变性少,巯基含量为38.98 nmol/mgpro,氧化程度低,羰基含量为0.92 nmol/mg pro;感官评价显示船上加工鱿鱼熟片色泽白皙、较有光泽,具有浓郁的鱿鱼香味,总体接受度高达9.78分。结论:船上加工秘鲁鱿鱼熟片肌肉组织坚实富有弹性,蛋白损失少,TVB-N含量为29.25 mg/100 g,符合GB 2733—2005《鲜、冻动物性水产品卫生标准》,总体品质比岸上加工鱿鱼熟片好,适于二次加工利用。