采用真空方法进行液体冻结的探索与分析研究

提出采用真空方式对液体进行冻结,并对抽空的温度、压力及释放热量的现象进行热力学分析。实验运用自行研制的真空冷却试验台,以水、糖水溶液及盐水溶液为冻结材料,实时检测降温与冻结过程中样品内外各点温度与压力的变化曲线,观察样品的变化状态。通过实验,了解了水与二元溶液真空冻结压力与温度的关系和冻结的特性,包括溶液的降温特点、沸腾现象、凝固现象等。实验结果显示,纯水的冰质地较致密而光滑;盐水的冰质地较松软,空隙较大,有明显的冰颗粒;糖水的冰,质地更加的松软,颗粒细腻,类似于冰沙。最后对采用真空技术应用于食品的冷却与冻结工业进行了展望。     

高速搅拌辅助对真空预冷纯水过程中防飞溅的影响

研究真空预冷纯水下压强下降速率、冷媒温度及搅拌速率等操作参数,并通过对单位时间里的理论水分损失量、实际水分损失量、飞溅量及压强差等指标的分析来探讨对防飞溅的效果。结果表明:增加搅拌能够明显抑制真空预冷过程中纯水的飞溅。通过高清摄像头观察当转速增至900 r/min及以上时,大量爆沸和飞溅的现象未被观察到。在0.48 min-1压强下降速率和-10℃冷媒温度的条件下,当搅拌转速从0 r/min增至1 500 r/min时,其纯水飞溅率分别为27.37%,16.39%,8.25%,3.00%,2.97%和2.70%,而其所对应的最大压差值分别是885,436,411,182,189和172 Pa,表明预冷过程中最大压差值与水飞溅率存在相关性(R2=0.93),并且可将900 r/min作为纯水防飞溅的临界转速。通过增加搅拌不仅不会对预冷速率产生负影响,反而会加快预冷速率。     

食品加工业中极具应用潜力的真空冷却技术

真空冷却是在真空下水分快速蒸发的预冷技术 ,可用于食品尤其适于叶类蔬菜的冷却。本文介绍了真空冷却技术的原理、在食品加工中的优缺点及其在水果、蔬菜、肉制品、鱼制品、调味品和焙烤食品中的应用     

真空冷却技术在熟肉制品工业化生产中的应用研究

真空冷却技术是依据较高温度的含水物料在密封环境中真空的条件下通过水分迅速蒸发使物料自身得到迅速降温冷却的原理,这项快速蒸发冷却技术过去仅局限应用在蔬菜和鲜花的冷却保鲜等领域中,本课题研究真空冷却技术应用在熟肉制品生产的冷却工艺中,实验结果表明:相同的熟肉产品从95℃冷却到20℃,真空冷却比传统自然冷却速度快20倍以上,该技术可有效防止微生物在产品中的污染和增殖,提高产品的质量和安全性,延长产品货架期。研究同时就真空冷却技术对产品失水率的影响作了探讨。     

一次性饮料自行冷却罐

<正>据英国《新科学家》周刊报道,佛罗里达州的一位发明家发明了一种一次性自行冷却罐,采用沸水冷却所装的饮料。 水并不总是在100摄氏度时才沸腾。如果水面上的气压降低了,那么它的沸点也会降低。如果水是在真空里,那么它的沸点将会降低到接近0摄氏度。一次性饮料自行冷却罐便是利用这个原理。这种罐有两个室,其中上面的那个室几乎装满需要冷却的饮料。罐里的空气全部抽掉后便生成一个真空,但是饮料上空的那个空间很快便充满水蒸汽,所生成的压力     

肉制品真空冷却技术研究进展

肉制品在热加工后需要进行快速冷却,以避免熟肉中微生物繁殖及保证品质。然而,传统的冷却方法难以满足这一要求,尤其是肉制品核心温度的降低。真空冷却技术的冷却速度快且冷却均匀,可快速降低熟肉制品的温度,进而延长产品的货架期和贮藏期等。但与此同时也带来了一些问题,如失重率高、投入成本较高等。真空冷却技术作为具有独特发展潜力的食品快速冷却技术,其特有的优势促使了人们对其的深入研究。为促进真空冷却技术的发展,本文综述了肉制品真空冷却技术的研究进展。     

食品加工业中极具应用潜力的真空冷却技术

真空冷却是在真空下水分快速蒸发的预冷技术，可用于食品尤其适于叶类蔬菜的冷却。本文介绍了真空冷却技术的原理、在食品加工中的优缺点及其在水果、蔬菜、肉制品、鱼制品、调味品和焙烤食品中的应用。     

冷却对熟粽子品质的影响

粽子在蒸煮后需冷却。为了寻找合适的冷却方法,通过真空冷却、冷风冷却、自然冷却3种方式处理煮后的3种速冻粽子,测定这些粽子的品质差异。结果表明:与常规冷却方式相比较,真空冷却速率高(P0.05),冷却损失较高(P0.05)。质构分析表明:真空冷却产品硬度较大(P0.05),而黏着性、弹性、内聚性、胶黏性、咀嚼性和回复性方面没有显著差异(P0.05)。感官分析表明:真空冷却的产品口感虽然不及常规冷却的产品,但在可接受的范围。化学指标分析表明,真空冷却能显著降低菌落总数。电子鼻分析结果表明:豆沙粽子和肉粽子真空冷却与常规冷却的产品挥发性气味显著不同,而对白粽子的影响不显著。真空冷却是一种快速、安全的冷却方法。     

真空泠却技术在熟肉制品工业化生产中的应用研究

真空冷却技术是依据较高温度的含水物料在密封环境中真空的条件下通过水分迅速蒸发使物料自身得到迅速降温冷却的原理，这项快速蒸发冷却技术过去仅局限应用在蔬菜和鲜花的冷却保鲜等领域中，本课题研究真空冷却技术应用在熟肉制品生产的冷却工艺中，实验结果表明：相同的熟肉产品从95℃冷却到20℃，真空冷却比传统自然冷却速度快20倍以上，该技术可有效防止微生物在产品中的污染和增殖，提高产品的质量和安全性，延长产品货架期。研究同时就真空冷却技术对产品失水率的影响作了探讨。     

它为你做菜你要对它好

微波炉也会累,微波炉积聚污垢过多时会影响电磁波的传播,导致受热不均。如果你不记得经常给它做个清洁,那么它的工作效率就会相应降低。烹饪后及时处理污垢的清洁尽量在刚刚加热完炉内还有蒸汽时进行,做微波莱后,炉门四周可能出现雾、水滴等,这属于正常现象,用软布及时擦干即可。因为高温会使食品的汤汁飞溅,可使用软布、温水及温和的清洁剂清洁微波炉内部表面、炉门的前后及炉门开口处。     

Effect of cooking bag and netting packaging on the quality of pork ham during water cooking

As a preliminary test for combining water cooking with vacuum cooling in soup of pork ham, three package treatments were designed to study the effect of cooking bag and netting on the quality of water cooked ham, i.e. ham cooked with a cooking bag and without a cooking bag (single netting and double netting). For treatments without a cooking bag, the results indicated that there was no significant superiority of ham cooked with double netting compared with ham cooked with single netting on the processing efficiency and quality characteristics. Although the hams cooked with a bag performed better in some chemical retentions and pigment, the water contents were significantly lower than those hams cooked in single netting (P<0.05), and there was a higher shrinkage tendency compared with the hams cooked without a bag. For the processing characteristics and texture properties of pork ham, there were no significant differences observed among the treatments with and without a cooking bag in terms of the combined effect of cooking and cooling (P>0.05). By considering the safety, convenience, cost, and the recovery effect on the quality changes of ham during vacuum cooling in soup, cooking with single netting is a better choice for future research.     

制汤工艺条件对猪排骨蛋白质溶出率的影响

以排骨蛋白质溶出率为指标,通过单因素试验及正交实验优化排骨汤煮制的工艺条件。结果表明:传统瓦罐煲汤法的骨水比例1:6(g:mL),煮沸后恒温120min,蛋白质的溶出率为19.73%。压力锅炖汤法的压力0.10MPa,骨水比例1:3(g:mL),煮制180min,蛋白质的溶出率达52.82%。木瓜蛋白酶用量2.4%,骨水比例1:4(g:mL),50℃,pH7.0,酶解420min,蛋白质的溶出率达到71.86%。3种制汤方法中酶解制汤法最佳,其水解液无苦味,色泽金黄,具有浓郁的排骨汤香味。     

不同熬煮时间对台湾泥鳅汤蛋白组分及抗氧化能力的影响

以台湾泥鳅为研究对象,分析不同熬煮时间(30、60、90、120、150 min)对泥鳅汤蛋白组分和抗氧化能力的影响。结果表明:随着熬煮时间的增加,汤中可溶性蛋白质含量显著(P<0.05)上升,在150 min达到18.49 mg/mL,同时汤中蛋白质水解成不同大小的短肽以及游离氨基酸。泥鳅汤中总游离氨基酸含量、必需氨基酸含量、鲜味氨基酸含量随熬煮时间的增加先上升后下降,在90 min时,总氨基酸含量最高到达2957.2 μg/mL,鲜味氨基酸含量为1296.7 μg/mL。随着熬煮时间的增加,泥鳅汤的ABTS+·清除率和DPPH·清除率均呈上升趋势,尤其是DPPH·清除率在熬煮30~90 min范围内从11.66%上升到84.10%。因此在熬煮90 min时,泥鳅汤的营养品质和抗氧化能力均较好。     

食用菌火锅底汤的安全性研究

目的：针对火锅底料长时间熬制可能出现污染物富集等不足,探讨使用食用菌为主料加工高品质火锅底料的可行性。方法：以松茸、茶树菇、香菇、金针菇为主料加工火锅底汤,测定其硝酸盐、嘌呤、重金属等指标的变化,据此优化该火锅底汤熬制工艺。结果：经熬制8 h,硝酸盐类总量低于饮用水标准的限量;嘌呤含量低于常人安全饮用限量,也适合除痛风患者急性期以外的人群饮用,属于低嘌呤食品;铅、铬、铜、镍均低于限量标准,但镉在熬制5 h时含量稍高。结论：建议该食用菌火锅底汤熬制时间为4 h。     

An innovative method of immersion vacuum cooling for cooked meat products: immersion vacuum cooling with ultrasonic assistance

In this paper, immersion vacuum cooling with ultrasonic assistance (IVCUA) is compared with immersion vacuum cooling alone (IVC) and vacuum cooling (VC) for cooling time, mass loss, colour, texture profile and water mobility and compartmentalization for cooked meat products. The results reveal that IVCUA clearly enhances the boiling intensity of impregnation liquid compared to IVC. The total cooling time using IVC (126.56 min) for samples from 72 to 4 °C was significantly longer (P < 0.05) than that of IVCUA (96.89 min) and VC (80.48 min). The cooling time of samples from 10 to 4 °C by IVC (46.26 min) was higher (P < 0.05) than that by IVCUA (28.55 min). There were no significant differences (P > 0.05) in mass loss, colour and texture profile among all samples. However, IVCUA had a higher transverse relation time of bulk water (T₂₄) and MRI proton densities (P < 0.05), as well as a more uniform water distribution compared to IVC.     

IMPROVING THE QUALITY OF PORK HAM BY PULSED VACUUM COOLING IN WATER

Vacuum cooling of pork ham with water, or immersion vacuum cooling, is a successful method to compensate the high mass loss of traditional vacuum cooling. In order to further optimize vacuum cooling with water, pulsed vacuum cooling was designed to study the effect of different cycles on the quality of pork ham, i.e., in one cycle, four cycles and eight cycles. The result indicated that increasing pulse cycles during vacuum cooling of pork ham with water would reduce the cooling loss with compatible cooling time. Tests on the physical properties of pork ham disclosed that tenderness and water‐holding capacity could be improved by increasing pulse cycles during vacuum cooling with water. However, There was no significant difference observed between pork ham in 4 pulse cycles and 8 pulse cycles (P > 0.05). Therefore, treatment of 4 pulse cycles was adopted for future research related to vacuum cooling of pork ham with water.     

Feasibility assessment of vacuum cooling of cooked pork ham with water compared to that without water and with air blast cooling

To optimise vacuum cooling for application in the meat industry, an improved cooling method, i.e. vacuum cooling with water (or immersion vacuum cooling), was designed to cool cooked pork ham (2.2 ± 0.2 kg). It was found that the cooling time of vacuum cooling with water was significantly shorter than that of traditional air blast cooling (P < 0.05). For the cooling loss, vacuum cooling with water was significantly lower (6.99%) than that of vacuum cooling without water (13.71%) (P < 0.05). Significant differences in physical and chemical attributes were also observed for ham processed by vacuum cooling with and without water (P < 0.05). Therefore, for a certain size of pork ham, vacuum cooling with water could be an effective method to meet safety guidelines and obtain compatible quality attributes with air blast cooling.     

反复卤煮对鸭胸肉和卤汤中杂环胺及其前体物的影响

为探究卤汤反复使用对鸭胸肉和卤汤中杂环胺及其前体物的影响,本文以鸭胸肉为原料,模拟盐水鸭的制作工艺,测定鸭肉和卤汤中杂环胺及其前体物的含量。结果表明:随着卤汤使用次数的增多,鸭肉和卤汤中肌酸、氨基酸、葡萄糖含量均显著升高(p<0.05)并且卤汤中前体物上升速率大于鸭肉。鸭肉和卤汤中杂环胺总量随卤煮次数直线上升,线性方程分别为y=0.0224x+1.7209(R2=0.9871)和y=0.0157x+0.3821(R2=0.9442)。卤汤反复使用40次后,鸭肉和卤汤的杂环胺总量分别为2.74、1.08 ng/g。卤汤反复使用过程中,鸭肉和卤汤中肌酸、氨基酸、葡萄糖含量呈现上升趋势,同时杂环胺也不断富集。因此,应尽量避免卤汤的反复使用。     

盐质量分数对鱼头汤熬煮过程中微纳米颗粒形成的影响

目的:探究盐质量分数对金枪鱼头汤熬煮过程中微纳米颗粒(micro/nano particles,MNPs)形成的影响.方法:在优化的鱼水质量比1:8、油煎时间40 s、油煎温度120℃、熬煮时间150 min条件下熬煮鱼头汤,探究不同的加盐质量分数(0.3％、0.4％、0.5％、0.6％、0.7％)对熬煮鱼头汤中营养物...