Selected Mechanical Properties of Pomegranate Peel and Fruit

Mechanical property data of pomegranate fruits are limited. The objective of this study was to determine the compression and cutting properties of whole fruit as well as the puncture strength of peel samples of fruit at different storage times. The results showed that storage time had a significant effect on all the properties studied in this work except for peel shear strain (p < 0.05). The whole fruit cutting energy and power, maximum cutting force, peel shear strength and strain and shear modulus showed an increasing trend with storage time. However, firmness, bioyield force, and modulus of elasticity increased and then decreased with storage time.     

果蔗贮藏保鲜技术初探

本试验对不同贮藏保鲜处理的果蔗品质的变化进行研究,结果表明,采用低温贮藏可有效地防止果蔗品质劣变,真空包装去皮果蔗能延长其保质期。     

The effect of impact and fruit properties on the bruising of peach

Peach fruit quality is adversely affected by bruise damage. In order to reduce this damage, it is necessary to know the influence of fruit properties on bruise susceptibility. Two bruise prediction models were constructed for the damage susceptibility of peach fruit (measured by bruise volume) using multiple linear regression analyses. In the first model, peak contact force and three fruit properties (acoustic stiffness, fruit temperature and radius of curvature) were used as independent variables. In the second model, peak contact force was replaced by the impact energy. Peaches were subjected to dynamic loading by means of a pendulum at three levels of impact. Significant effects of acoustic stiffness, temperature and the radius of curvature and some interactions on bruising were obtained at 5% probability level with the coefficient of determination of 0.97 and 0.98 for models 1 and 2, respectively. It was concluded that lowering the temperature and increasing the radius of curvature and acoustic stiffness will reduce the bruise damage of the peach fruit.     

Physico-chemical Properties, Vitamin C Content, and Antimicrobial Properties of Pomegranate Fruit (Punica granatum L.)

Pomegranate (Punica granatum L.) fruit is widely used in the food and process industries due to its excellent nutritional and health value and as a raw material for the manufacture of secondary products such as jellies, dyes, and cosmetics. The objectives of this research were to determine the vitamin C content and antimicrobial properties of fresh and dried fractions of fruit peel and arils of locally grown and imported pomegranate in Oman. A significant variation in vitamin C content was found among the five varieties of pomegranate studied, ranging from 52.8 to 72.0 mg/100 g fresh weight (fw) for arils and 76.8 to 118.4 mg/100 g fw for peels. Irrespective of the variety of pomegranate, vitamin C content in the peel was significantly higher than the aril, with differences ranging from 24.4% to 97.0% depending on variety. Fruit fractions showed antimicrobial effects (inhibition zone) on Staphylococcus aureus and Pseudomonas aeruginosa but not Escherichia coli. Sun drying of fruit peel significantly (p ≤ 0.05) enhanced vitamin C retention and antimicrobial effects in comparison with oven drying presumably due to lower rate of moisture removal associated with low temperature drying over longer duration in comparison with short-time high-temperature oven drying.     

不同储藏时间及温度对荞麦淀粉特性的影响

采用碱液提取法提取荞麦淀粉,研究了不同储藏时间及温度对荞麦淀粉特性的影响。考察了提取物的水分、淀粉纯度、直链淀粉含量、淀粉膨胀度和溶解度的变化,并利用快速黏度仪和差示量热扫描仪分析了荞麦淀粉的糊化特性和热特性。结果表明,在4℃条件下储藏的荞麦,提取物的淀粉纯度高于38℃下储藏荞麦的淀粉纯度;储藏过程中,直链淀粉含量先下降再上升,淀粉膨胀度下降,且低温条件储藏时下降幅度更为明显。但储藏对淀粉溶解度和糊化特性无显著影响。38℃储藏的荞麦,淀粉初始糊化温度随储藏时间的延长先上升再下降,而4℃储藏的荞麦变化不显著。储藏过程中,糊化焓呈现先下降后上升趋势,且38℃条件下储藏的荞麦,该变化更为明显。研究可以为碗托等荞麦淀粉食品加工提供参考。     

贮藏温度对鲜食石榴籽粒贮藏品质及抗氧化能力的影响

研究不同贮藏温度(0、5、10℃和室温)对鲜食石榴籽粒贮藏品质、活性成分及抗氧化能力的影响。结果表明,与10℃和室温贮藏条件相比,0℃和5℃能减缓石榴籽粒的呼吸速率、抑制相对电导率和质量损失率的升高、提高抗氧化活性,大大延长了商品货架期。其中,0℃更好地保持了可溶性固形物含量和花色苷稳定性,并能保持更好的品质和货架期,因此,0℃可作为鲜食石榴籽粒最适宜的贮藏温度。     

石榴贮藏期间间歇升温处理对果实品质的影响

以陕西临潼净皮甜石榴为试材,研究了间歇升温处理对石榴果实贮藏期间品质变化的影响。结果表明:石榴在(5.0±0.5)℃条件下贮藏,每隔6 d在(15±0.5)℃下间歇升温处理24 h,能有效保持果粒可溶性固形物含量、总糖含量和可滴定酸含量,减缓果皮褐变指数升高速率,降低果实腐烂率,贮藏120 d果实外观色泽鲜艳.籽粒感官品质良好,保鲜效果理想。     

花前摘心对酿酒葡萄坐果率的影响

在宁夏贺兰山东麓地区，对5个主栽酿酒葡萄品种进行了不同时期、不同程度的摘心处理，结果表明：花前2天至初花期摘心有利于提高酿酒葡萄坐果率；摘心强度对坐果率的影响因品种而有差异。     

不同热处理方式对青枣贮藏保鲜效果的影响研究

以西昌地区的青枣为试材,研究不同热处理方式对青枣贮藏保鲜效果的影响.结果表明：适宜条件的热水处理效果较好,其最佳条件为55℃处理10 min,30 d腐烂指数为8.61%,好果率为81.67%,可溶性固形物和酸含量分别为9.4%和4.06%,Vc含量为28.17 mg/100 g.     

Experimental study of drop impacts and spreading on epicarps: Effect of fluid properties

The fluid mechanic of liquid drop impacts on solid food plays an important role in food engineering, e.g. when a spray technology is used to apply a coating. In the present work, drop impact behavior on banana and purple cabbage epicarps using high speed camera was studied. Drop velocity was controlled by modifying the height from which drop was ejected. Weber number varied from 100 to 800, whereas Reynolds number ranged from 1000 to 12,500. Liquid drop viscosity and surface tension effects on drop impact behavior were evaluated and temporal evolution of both spreading and flattening factors are presented. Results show that viscosity and epicarp surface properties had great influence on impact dynamics. For low viscosity liquid drops (water and Tween 20-water), the maximum spread factor, ξ_max, scaled with We^0.25±0.02, whereas for viscous fluid (water-glycerol mixture) it scaled with We^0.16±0.02. Finally, a new model was proposed to better fit the experimental data than the Roisman’s and Scheller’s models.     

Effects of fining treatment and storage temperature on the quality of clarified banana juice

The clarified banana juice was subjected to different treatment namely bentonite, combination of gelatin and bentonite and control and stored at 4, 25 and 37 °C for 24 weeks. The effects of fining treatment, storage temperature and storage time on turbidity, total polyphenol, browning index, microbiological, and sensory quality of clarified banana juice were evaluated during storage. Fining treatment, storage temperature and storage time had a significant (p<0.001) effect on turbidity, total polyphenol and browning index of clarified banana juice. Turbidity and browning index of juice were reduced by fining treatment with bentonite and a combination of gelatin and bentonite but increased with storage temperature and storage time. A significant decrease in total polyphenol content and increase in turbidity and browning index were detected for all juice samples during storage. However, it was noted that changes were significantly greater in control juice stored at higher temperature than in juice stored at 4 or 25 °C for up to 6 months. Sensory evaluation revealed that juices treated with bentonite or a combination of gelatin and bentonite and stored at 4, 25 or 37 °C were acceptable for up to six months, whereas untreated juice stored at 37 °C was only acceptable for up to 16 weeks.     

橄榄果实冷藏期间失重影响因素的研究

对福建省10个主栽橄榄品种果实在8℃、RH85%贮藏条件下的果实失重率及贮藏温度(2℃、6℃、10℃、20±1℃室温)、贮藏时间及包装对果实失重率的影响进行研究.结果表明,橄榄各品种随贮藏天数的增加,果实失重率呈线性增加;供试的10个橄榄品种,以中长营最易失水,福州品种群大长营、中长营、小长营较容易失水,莆仙品种群厝后本、刘族本保水性能较好,其中刘族本果实失重率显著(P<0.05)地低于其它品种果实.没有包装的檀香橄榄果实失重率与贮藏温度、贮藏时间呈显著(P<0.05)正相关,即橄榄果实失重率随贮藏温度升高(相关系数r=0.9560～0.9999),贮藏时间延长(r=0.9692～0.9960)而增加,且它们间存在互作效应,橄榄不同品种与贮藏时间之间也存在互作效应.用0.04mm厚聚乙烯薄膜袋包装,可有效地控制橄榄果实的自然失水,与对照组没有包装间存在极显著(P<0.01)差异,因而延长了橄榄果实贮藏期.     

微波处理对货架期石榴品质的影响

利用微波炉对采后石榴果实进行辐照处理,研究处理后果实在货架期的生理变化及贮藏品质。结果表明：10～20s 短时微波处理可抑制果皮多酚氧化酶(PPO)活性,减轻果实的褐变程度,保持果皮较高的多酚含量,减缓可滴定酸(TA)含量降低的速度,较好的保持了可溶性固形物含量(SSC)。10～20s 是适宜的微波处理时间,超过20s会产生热伤害,加重果实褐变。     

石榴果酒发酵工艺的研究

以成熟石榴汁为原料,对石榴果酒发酵工艺进行研究.确定石榴酒发酵工艺为:pH4.0、糖度为16,加入6 g/L果胶酶、0.20 g/L葡萄酒酵母,在24℃条件下前发酵4 d后,分2次添加葡萄糖,在18℃后发酵20 d,使其最终酒度在12%vol左右.将发酵醪陈酿、澄清、包装、灭菌后得到酒体醇厚、酸涩适中的深红色澄清石榴果酒.     

石榴果醋酿造工艺研究

以新鲜石榴汁为原料,通过单因素试验和正交试验探讨了石榴果醋酿造的最佳工艺条件.结果表明:酒精发酵最佳工艺条件为发酵温度30℃,酵母菌接种量0.07％,发酵时间5天.醋酸发酵的优化工艺条件为醋酸菌接种量10％,发酵温度28℃,初始酒精度7％.配制的石榴果醋饮料色泽棕红,无沉淀物,酸味柔和,具有石榴果醋特有的醋香气.     

Effect of high pressure on the microbiological quality of cooked chicken during storage at normal and abuse refrigeration temperatures

Vacuum-packaged cooked poultry meat was treated at a range of pressures (400–600 MPa) and hold times (1, 2 and 10 min), followed by storage at 4°, 8° or 12 °C for up to 35 days. Weissella viridescens was found to be the dominant microorganism in the pressure-treated meat, constituting 100% of the microflora identified at 500 and 600 MPa. None of the pressure-treated samples had obvious signs of spoilage during the 35 day storage period, even when the Weissella count was >7 log₁₀ cfu/g. Studies on a typical W. viridescens isolate showed it to be relatively pressure-resistant in poultry meat, with <1 log reduction in numbers after a treatment of 2 min at 600 MPa. Agar diffusion assays showed that the isolate also caused the inhibition of a number of Gram-positive and Gram-negative pathogens, including strains of Clostridium botulinum, Listeria monocytogenes, Bacillus cereus and Escherichia coli. The selection of a pressure-resistant organism, such as this Weissella sp. could be advantageous in extending the shelf-life, and also microbiological safety, of the cooked meat, as it could give protection in addition to the pressure treatment itself.     

不同储藏条件对小米风味的影响

脱壳的小米稳定性较差，不良储藏条件容易导致小米品质劣变，影响加工后的米粥风味。探索不同储藏温度和时间对小米风味的影响，明确适宜储藏条件具有重要意义。本实验以3个名优品牌小米为研究材料，在常温和4℃低温避光储藏一年，分别在储藏0，3，6，9，12个月时，利用顶空固相微萃取结合气相色谱质谱联用仪（HS-SPME-GC-MS）测定小米蒸煮挥发性物质。结果表明：在常温与4℃低温一年储藏期间内，醛类、醇类、杂环类及烷烃类物质相对含量变化整体呈“W”型；酸脂类呈“M”型。在4℃低温储藏条件下，醛类、醇类和酚类等物质相对含量较常温条件下更高，风味物质更丰富。正己醛、1-辛烯-3醇、正壬醇、2-正戊基呋喃和对二甲苯为储藏小米的关键香味物质。储藏小米最佳食用期限为4个月，低温储藏效果更好。该研究结果对小米储藏保鲜和品质育种提供理论基础。     

预冷时间对生鲜农产品贮藏品质的影响

为了降低生鲜农产品在流通与销售过程中的数量和质量损失,本文研究了不同预冷时间对生鲜农产品贮藏品质的影响。将新鲜采摘的西红柿、黄瓜、西葫芦、蒜薹四种生鲜农产品平均分成三组,分别在实验平台预冷0 h、10 h和20 h,通过微孔袋包装并扎口,放入冷藏库中冷藏18 d,每3 d进行一次取样。研究不同预冷时间对农产品失重率、硬度、呼吸速率与乙烯生成速率、腐烂率、可溶性固形物含量、Vc含量、感官评分、丙二醛、过氧化物酶活性的影响。结果表明,在贮藏时间达到18 d时,未经预冷处理的农产品腐烂率与失重率最高,分别是21.51%,63.29%,可溶性固形物最低,含量仅为12.11%,10 h预冷时间下腐烂率、失重率与可溶性固形物均控制得较优。针对抗氧化性能,10 h与20 h预冷时间下抗氧化性能和未预冷相比明显升高,且10 h预冷时间抗氧化性能最高,农产品外观品质保持较好。说明经预冷处理农产品贮藏品质均优于未经预冷处理,整体看来10h预冷时间农产品贮藏品质优于20 h预冷时间,可以降低农产品在运输销售途中的损失,使得农产品的新鲜程度有了保障。     

Long-Term Storage Effects on the Physical Properties of the Potato

Determination of physical properties of agricultural products, such as the potato, and their variations during long-term storage, is an important feature in achieving high product quality and consumer acceptance. Physical properties of potatoes (Agria, Satina, and Caesar cultivars), including surface area, volume, moisture content, weight, and three main diameters of tuber, were measured and then other properties, such as sphericity, roundness, geometric mean diameter, volume mean diameter, aspect ratio, effective diameter, and real density during storage time, were calculated. The measurements were done every 15 days for a period of 22 weeks and analyzed based on a completely randomized block design in ten replications. Significant differences were observed among three potato cultivars according to major diameter, shape characteristics, mass, volume, and surface area of tubers. In this relation, Satina was larger in size compared to the two other cultivars. However, the Agria cultivar was closer to a sphere in shape. Also, it was found that the surface area of each potato could be estimated based on its mass and volume by a power law equation with a high coefficient of determination. According to the results, real density of tubers increased as a function of storage time based on a polynomial equation with R² = 0.99. During storage time, moisture content of tubers decreased according to a linear model and was probably the major rationale for decrease in tuber size. Density, size, and moisture content are the major physical characteristics of potato tubers, which change dramatically during long-term storage. Considerable differences in physical properties of different cultivars persuade researchers to carry out further studies on other popular potato cultivars.     

不同煮制温度对新疆熏马肉品质的影响

目的：本实验旨在研究不同煮制中心温度对新疆熏马肉熟化过程中品质的影响。方法：测定煮制中心温度为60、65、70、75、80、85、90、95 ℃时,熏马肉的蒸煮损失、色泽、剪切力、肌节长度、肌纤维直径,并分析质构特性。采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecyl sulfate polyacrylamide gel electrophoresis,SDS-PAGE）分析熟化过程中蛋白质的变化。结果：随着中心温度的升高,蒸煮损失率显著增大（P＜0.05）。色泽a*、b*值呈先减少后增加的趋势,L*值先增加后减少,在70 ℃时a*、b*值达到最小值,L*值达最大值。剪切力与肌纤维直径均呈先增加后减少的趋势,并且剪切力与肌纤维直径成正相关（r＝0.777）。肌节长度显著降低（P＜0.05）。中心温度升高,硬度显著增大（P＜0.05）;弹性呈先增加后减少趋势;黏聚性与咀嚼性呈先减少后增加的变化趋势。SDS-PAGE结果表明,随着中心温度升高,大分子质量蛋白质发生降解。结论：煮制中心温度70 ℃是影响熏马肉品质的关键温度。