Kinetics of the thermal destruction of thiamine in the white flesh of rainbow trout (Salmo gairdneri)

Thin slices of white flesh from rainbow trout (Salmo gairdneri Richardson) were given different time—temperature treatments and the D and z values for total thiamine were determined. The z value (26°C) was in good agreement with previously reported data but the D values were considerably lower than published results. Thiamine appears to be less thermally stable in the fish muscle than was previously thought. This has serious repercussions when optimising thermal processing with respect to nutrient retention.     

Thermal Stability of Bovine Milk Immunoglobulin G (IgG) and the Effect of Added Thermal Protectants on the Stability

D and z values and some thermodynamic parameters of immunoglobulin G (IgG) in phosphate buffer solution (PBS) (0.15 M NaCl/0.01 M phosphate buffer, pH 7.0) and colostral whey, with or without the presence of thermal protectants, were calculated in model systems. The D and z values for separated IgG in PBS were much lower than those for separated IgG in 20% glycerol, whey, and whey with 20% glycerol. IgG in colostral whey showed larger D and z values with the protectants. The heat denaturing rate constants at 70-82°C for separated IgG in PBS were larger than those of IgG in colostral whey; and the energies of activation for separated IgG in PBS, 0.2% glutamic acid, 10% whole milk, 20% maltose and 20% glycerol were also larger.     

成熟温度对Mozzarella干酪蛋白水解和质构的影响

研究了温度为4,7,10℃时对干酪成熟过程中蛋白水解和质地的影响。结果表明,随着干酪成熟温度的升高,成熟期间干酪中可溶性氮与总氮的比值增加较快,干酪的硬度下降速度也较快。说明在较高的成熟温度下,干酪在较短的时间内能够达到成熟的状态。     

Effect of heat on microorganisms isolated from freshly caught chilled scad (Trachurus trachurus)

The effects of heat on bacteria making up part of the microFlora of the sea-Fish Trachurus trachurus were studied. From 80 bacterial isolates which were subject to primary identiFication four were selected. The bacteria were subjected to a heat stress of 55°C for 20 s both in pure and mixed suspensions, the D-values and post-stress recovery in nutrient broth were measured. Using differential plating on selective agents to identify sites of injury and recovery times, the growth parameters dissolved oxygen, redox potential and pH were measured during recovery. Bacteria presumptively identiFied as Shewanella putrefaciens and Pseudomonas putida were more sensitive to heat than other bacteria, suggesting that most heat treatments of Fish may reduce the number of these bacteria. After dissolved oxygen was used up during recovery in nutrient broth, Eh declined from positive to negative values typical of facultative bacteria showing that, after initial aerobic growth, the bacteria changed their metabolism to grow anaerobically. When dissolved oxygen reached zero, about 120 h after inoculation, the numbers of all bacteria were about 10⁷mL⁻¹, and corresponds to a minimum in the pH values, except for the most heat sensitive isolate (300 h after inoculation). Differential plating showed increased sensitivity to NaCl induced by heat treatments in some isolates.     

Modeling the combined effects of pH, temperature and ascorbic acid concentration on the heat resistance of Alicyclobacillus acidoterrestis

In this study, thermal inactivation parameters (D- and z-values) of Alicyclobacillus acidoterrestris spores in McIlvaine buffers at different pH, apple juice and apple nectar produced with and without ascorbic acid addition were determined. The effects of pH, temperature and ascorbic acid concentration on D-values of A. acidoterrestris spores were also investigated using response surface methodology. A second order polynomial equation was used to describe the relationship between pH, temperature, ascorbic acid concentration and the D-values of A. acidoterrestris spores. Temperature was the most important factor on D-values, and its effect was three times higher than those of pH. Although the statistically significant, heat resistance of A. acidoterrestris spores was not so influenced from the ascorbic acid within the concentration studied. D-values in apple juice and apple nectars were higher than those in buffers as heating medium at similar pH. The D-values ranged from 11.1 (90 °C) to 0.7 min (100 °C) in apple juice, 14.1 (90 °C) to 1.0 min (100 °C) in apple nectar produced with ascorbic acid addition, and 14.4 (90 °C) to 1.2 min (100 °C) in apple nectar produced without ascorbic acid addition. However, no significant difference in z-values was observed among spores in the juices and buffers at different pH, and it was between 8.2 and 9.2 °C. The results indicated that the spores of A. acidoterrestris may survive in fruit juices and nectars after pasteurization treatment commonly applied in the food industry.     

不同贮藏和食用方式对小青菜中亚硝酸盐含量的影响

采用国标的方法测定室温下贮藏的小青菜的亚硝峰值为10-34mg／kg,大大高于在4℃贮藏条件下的小青菜;4℃不密封和4℃密封两种贮藏方式亚硝峰最高峰都在第4d,分别为6．48nag／kg和5．31mg／kg;浸泡处理30min后,亚硝酸盐的含量仅为1．02mg／kg,比鲜样降低了45％;烫漂90S后亚硝酸盐含量有所降低;小青菜中亚硝酸盐含量会随着食盐添加量增大呈现增加趋势,添加小青菜质量0．8％的食盐使小青菜中亚硝酸盐含量增加了81％;小青菜炒制后贮藏24h,未添加唾液的样品亚硝酸盐含量为2．29mg／kg,添加唾液的样品24h时含量达到2．72mg／kg。通过正交试验,炒小青菜的最佳处理方式为浸泡60min、漂烫120S、食盐添加量为小青菜质量的0．1％。     

钙处理对干装苹果罐头质地的影响

采用质地多面分析方法(TPA),以清水处理为对照,研究碱性钙(氧化钙、氢氧化钙)、无机钙(氯化钙、碳酸钙、硫酸钙)、有机钙(乳酸钙、醋酸钙、丙酸钙)对干装苹果罐头质地参数(硬度、回复性、弹性指数、咀嚼性、内聚性)的影响,并对TPA参数之间及其与感官品质间的相关性进行了研究.结果表明:与对照相比,除硫酸钙以外,各处理对干装苹果罐头质地均有明显的影响,经碱性钙(氧化钙和氢氧化钙)处理的干装苹果罐头硬度适中,回复性、弹性指数、咀嚼性、内聚性、感官品质均较好.回复性、弹性指数、咀嚼性、内聚性之间的相关性均显著,硬度与感官品质之间呈显著正相关关系.表明碱性钙对干装苹果罐头有较好的作用,并保持良好的质构.     

钙处理对干装苹果罐头质地的影响

采用质地多面分析方法(TPA),以清水处理为对照,研究碱性钙(氧化钙、氢氧化钙)、无机钙(氯化钙、碳酸钙、硫酸钙)、有机钙(乳酸钙、醋酸钙、丙酸钙)对干装苹果罐头质地参数(硬度、回复性、弹性指数、咀嚼性、内聚性)的影响,并对TPA参数之间及其与感官品质间的相关性进行了研究。结果表明:与对照相比,除硫酸钙以外,各处理对干装苹果罐头质地均有明显的影响,经碱性钙(氧化钙和氢氧化钙)处理的干装苹果罐头硬度适中,回复性、弹性指数、咀嚼性、内聚性、感官品质均较好。回复性、弹性指数、咀嚼性、内聚性之间的相关性均显著,硬度与感官品质之间呈显著正相关关系。表明碱性钙对干装苹果罐头有较好的作用,并保持良好的质构。      

Color degradation kinetics of pineapple puree during thermal processing

Improvement of color, as a quality attribute of processed pineapple puree, has been made possible by the increase in knowledge of kinetic of color change. The kinetics of color degradation of pineapple puree were investigated during heat treatment at 70-110 °C in order to cover the temperature range that used in preheat and sterilization of commercial aseptic pineapple puree. Color changes associated with heat-treated puree were monitored using Hunter colorimeter (L, a, b, total color difference—ΔE) and Browning index (A₄₂₀). The changes in L and b values fitted well to the first-order kinetic model while ΔE, a value, and Browning index followed the zero-order kinetic. The dependence of the rate constant on temperature was represented by an Arrhenius equation. The results suggested that ΔE and lightness, based on activation energy, were the most sensitive measures of color change at temperature range 70-90 and 95-110 °C, respectively.     

Factors influencing the drained weight,texture and other processing characteristics of canned strawberries

The influence of variety, spin cooking and vacuum closing on the quality of canned strawberries was investigated. The characteristics observed were drained weight, pH, acid concentration and texture. A new variety named Majestic had significantly higher drained weight, acid concentration, pH and texture than Phenomenal, the major variety grown in Queensland. It also had a higher drained weight value when grown in one particular area. With the Phenomenal variety, spin cooking, compared with rotary atmospheric cooking, gave a significantly higher drained weight. In addition, the fruit retained its shape and did not collapse to the same extent. For both varieties vacuum closing gave significantly higher drained weight and acid concentration in the drained syrup than steam-flow closing methods.     

The effect of processing on the texture of canned mung bean (Phaseolus aureus) shoots

The effect of various processing regimes on the pectic substances and the final texture of canned mung bean shoots has been studied. A blanching temperature of 75°C for 30 s was optimal in activating the native pectinesterase of the shoots and a holding temperature of 55°C for an optimal 30 min led to maximal deesterification of pectin. This treatment resulted in a canned product that was superior to a sample blanched at 100°C.; the addition of calcium ions did not improve the product.     

宠物罐头食品的营养调控及工艺优化研究进展

宠物罐头作为满足宠物犬猫营养和能量需要的重要主食饲料来源之一,近几年其规模逐渐增大,产品日益受到养宠主人的青睐.相比传统的膨化干粮,宠物罐头具有更好的适口性,更高的能量密度.本研究从宠物罐头的适口性、营养学特点、凝胶剂的选择及微生物控制等方面系统阐述宠物罐头的生产工艺要点和国内外研究进展,以期能够规范宠物罐头市场,促进...     

热加工对鲤鱼质构的影响研究

通过质地剖面分析TPA(texture profile analysis),测定不同的加热温度和时间下鱼肉的硬度、咀嚼性、内聚性、弹性和回复性,通过其变化趋势,分析加热对鲤鱼肉质构和品质的影响。TPA结果:30℃低温加工的鱼肉的蛋白质降解适度,肉质结实,富有弹性,有咀嚼感,鲜嫩,可以最大限度的保持了原有营养和固有的风味。     

干装苹果罐头贮藏过程中质地与细胞壁组分的变化

以干装苹果罐头为研究对象,采用TPA质构分析和乙醇不溶物（AIR）法,研究干装苹果罐头（4±1） ℃和常温贮藏过程中质地和细胞壁组分的变化,并探讨其质地参数和细胞壁组分变化的相关性。结果表明,低温贮藏能延缓干装苹果罐头质地和细胞壁组分的变化,（4±1） ℃贮藏的在24个月时硬度、回复性、咀嚼性、内聚性的变化率分别为0.74%、1.92%、0.25%、0,水溶性果胶（WSF）降低率为5.45%、螯合剂溶性果胶（CSF）和碳酸钠溶性果胶（NSF）升高8.88%和24.49%、半纤维素组分（HF）降低14.15%;常温贮藏的在12个月时硬度、回复性、咀嚼性、内聚性的降低率分别为3.93%、3.85%、11.36%、3.45%,WSF降低率为7.27%、CSF和NSF升高0.58%和4.08%、HF降低14.41%,质地参数与WSF呈负相关,与CSF、NSF、HF呈显著正相关。     

漂烫黄秋葵嫩果力学质地变化及评价方法的研究

为探讨漂烫黄秋葵嫩果的力学和色泽质地变化规律以及建立漂烫黄秋葵嫩果力学质地评价方法,用TA-XT2i质地分析仪对漂烫黄秋葵嫩果横切片进行了两种接触方式的硬度测定,并测定了不同漂烫温度、漂烫时间和冷却条件下黄秋葵嫩果的硬度,同时用DC-P3色差仪进行了色泽测定。实验表明,用棱接触压缩实验的压缩功评价漂烫黄秋葵硬度优于棱面接触压缩实验;黄秋葵嫩果经40、60℃漂烫后冷激能更好地保持原来硬度、色泽,且沿长度方向其硬度呈下降趋势;经80、100℃高温漂烫后,黄秋葵嫩果发生软化和褐变;综合力学和色泽质地的分析,黄秋葵嫩果最佳漂烫方法为60℃漂烫30⁶0s后冷激。本研究表明用棱接触压缩实验法评价漂烫黄秋葵力学质地变化是可行的,本实验为漂烫黄秋葵力学和色泽质地变化提供了参考。      

三种原料前处理方式对淮山罐头品质的影响

为解决热烫预处理易造成淮山罐头汤汁浑浊的问题,提高淮山罐头品质,分析比较热烫处理和以果葡糖浆为渗透液的真空渗透处理、常压渗透处理三种原料预处理方式对淮山罐头品质的影响。结果表明,热烫处理虽然能够钝化多酚氧化酶和过氧化物酶活性,从而起到较好的护色作用,但是会对淮山的表面组织结构造成严重破坏,导致电导率增加,硬度下降达34.80%。常压渗透和真空渗透处理组的淮山,由于糖液的渗入,结构更加致密,在罐头加工前处理时间内,并不会使样品发生明显褐变,对细胞膜的破坏程度均远低于热烫处理。常压渗透5 h和真空渗透3 h、4 h、5 h的淮山硬度均较新鲜淮山有所上升,但抗坏血酸含量明显下降;真空渗透处理组的淮山组织结构更完整,所制成淮山罐头的感官评分高于相同渗透时间的常压渗透处理组和热烫处理组。真空渗透脱水预处理能有效减少淮山罐头浑汤问题,提高罐头品质。     

炖煮温度对干燕窝质构和风味的影响

目的:研究炖煮温度对干燕窝质构和风味的影响。方法:以干燕窝为主要原料,利用物性分析仪对不同炖煮温度的燕窝进行全质构分析,利用气相电子鼻检测分析仪和固相微萃取—气相色谱—质谱分析(SPME-GC-MS)方法对不同炖煮温度下的燕窝进行挥发性成分测定。结果:随着炖煮温度的升高,熟制燕窝的黏附性显著下降(P<0.01),回复性显著升高(P<0.05)。GC-MS从熟化后的燕窝中检出有效风味物质12种,其中醇类3种、醛类2种、酯类2种、酮类3种、酸类1种、醚类1种,分别占95,105,115℃熟制燕窝总检出物质的6.23%,49.34%,54.85%。结论:炖煮温度影响燕窝口感以及加工后的总体气味轮廓,熟制温度升高趋向于加强蛋清风味。95℃的样品中挥发性物质以酸类为主,105℃的样品以醇类为主,115℃的样品以酮类、醇类为主。     

Effect of the thermo‐alkaline treatment over the thermal degradation of corn starch

In this work, thermogravimetric data were used for to study the thermal degradation of corn starch with and without thermo‐alkaline treatment. Flynn–Wall–Ozawa, modified Coats–Redfern, and Kissinger methods were used to determine the activation energy. Corn starch treated with calcium hydroxide exhibited the highest activation energy values during the whole thermal degradation process which could be related to the physical crosslinking process between starch constituents and Ca ions as was confirmed by the infrared analysis. The energy activation was dependent of the conversion, indicating that this degradation is a complex process. DSC at high temperatures, used for starch, corroborated that the degradation in this material is a complex process governed by different chemical reactions. Thermo‐alkaline treatment has a decelerator role in thermal degradation of corn starch.     

The effect of heat treatment on the β-glucosidase activity in canned whole apricots

Summary. Undesirable odour and flavour in canned whole apricots are caused by the products of the β-glucosidase activity in the apricot kernels. the hydrocyanic acid content in canned apricots heat treated for 38 min at 86°C was found to be approximately 1 ppm, with no changes occurring even after long storage; the figure reached a maximum of 16–17 ppm after 150 days of storage at room temperature in fruit heat treated at the same temperature but for only 20 min.     

芦笋罐头加工工艺的研究

主要对芦笋罐头的加工工艺和配方进行了探讨。原料经过清洗、去皮、预煮、冷却、装罐、灌汤,然后通过真空封罐,经杀菌冷却制成芦笋罐头。实验结果表明8,0℃预煮3 min可保持其较好的色泽和组织状态。正交试验得到罐头罐液的最佳配方为糖0.8%,食盐2.0%,柠檬酸0.05%,抗坏血酸0.05%。罐头的适宜杀菌条件为121℃,10 min。