Maillard Browning of Common Amino Acids and Sugars

Common amino acids and amide derivatives have been ranked according to the intensity of Maillard browning formed when heated in an autoclave at 121°C for 10 min, under identical conditions, with each of the sugars D-ribose, D-glucose, D-fructose, α-lactose and sucrose. The amino compounds have been grouped into high, intermediate and low browning producing groups. Browning formed by heating a representative of each group with D-glucose, D-fructose and α-lactose at pH values ranging from 6–12 was studied. Maximum browning was obtained at a pH value of about 10 in all of the amino acid-sugar solutions tested.     

北太平洋鱿鱼(Todarodes pacificus)内脏自溶液总氨基酸组成质量评价和体外抗氧化性分析

采用自溶法水解鱿鱼内脏,测定鱿鱼内脏自溶液(squid viscera autolysates,SVAs)的蛋白质提取率、可溶性氮含量、游离氨基酸含量和水解度,分析SVAs总氨基酸组成,评价其营养价值,并对SVAs的体外抗氧能力进行分析。结果表明:SVAs的蛋白质提取率为(53.89±1.17)%、可溶性氮质量分数为(78.47±1.16)%、游离氨基酸质量浓度为(0.22±0.03)mg/m L、水解度为(14.73±2.02)%。SVAs中必需氨基酸含量占氨基酸总量的37.03%,呈味氨基酸(天冬氨酸、谷氨酸、丙氨酸和甘氨酸)含量占氨基酸总量的42.40%。氨基酸组成与联合国粮农组织/世界卫生组织推荐氨基酸评分标准模式和全鸡蛋蛋白质氨基酸模式相比较,得出SVAs是一种营养丰富、且氨基酸组成合理的优质蛋白源。研究还表明,SVAs具有良好的体外抗氧化能力,其中清除1,1-二苯基-2-三硝基苯肼自由基和羟自由基的IC50值分别为0.24 mg/m L和0.74 mg/m L,还原能力强于相同质量浓度的L-肌肽。     

Solute Effects at High Water Activity on Nonenzymatic Browning of Glucose-Lysine Solutions

The effect of different polyols (glycerol, propylene glycol, sorbitol, 1,3-butylene glycol, polyethylene glycol200, and polyethylene glycol 400) and various alkali metal chlorides (KCl, NaCl, LiCl, and CsCl) on the kinetics of nonenzymatic browning in glucose-lysine solutions, of high water activity (a_w) was studied. No particular inhibitory or promoting effect on browning of glucose-lysine solutions, when adjusting a, with the various polyols, was found. The alkali metal chlorides had a significant influence on the rate of browning and the relative effect of cations (Li > Na > K, Cs) paralleled the hydrated ionicradii in solutions.     

微生物发酵剂对兔肉脯游离氨基酸含量的影响

将植物乳杆菌（Lactobacillus plantarum）、木糖葡萄球菌（Staphylococcus xylosus）、汉逊德巴利酵母菌（Dabaryomyces hansenii）接种于兔肉糜中,发酵及烘烤制成兔肉脯,研究不同菌种对产品中游离氨基酸含量的影响。结果表明：三菌种单独发酵处理组中,游离氨基酸总量由高到低分别为：葡萄球菌处理组＞酵母菌处理组＞乳酸菌处理组,3 个处理组游离氨基酸总量均高于空白对照组,说明添加发酵剂促进了兔肉脯中蛋白质的分解,且其在兔肉脯中分解蛋白质产生游离氨基酸的能力依次递减;三菌种单独发酵处理组中,各种游离氨基酸的含量有增有减,说明不同发酵剂对蛋白质分解游离氨基酸的影响不同;三菌种混合发酵处理组总游离氨基酸含量及各氨基酸含量均高于空白对照组和单菌处理组,说明三菌种复合发酵分解蛋白质产生游离氨基酸的效果相对最好。     

荔枝干加工过程果肉糖分的变化与褐变

以糯米糍荔枝为原料,测定鲜果及不同加工阶段荔枝干的水分含量,用自动测色色差计测定不同阶段荔枝干的颜色变化,并用高效液相色谱法分析果糖、葡萄糖及蔗糖含量的变化。发现蔗糖含量整体呈下降趋势,在加工的前两个阶段蔗糖含量下降最多,终阶段几乎无变化;果糖、葡萄糖含量整体呈上升趋势,到褐变程度最大的第二及终阶段含量达到最大;葡萄糖和果糖参加美拉德反应的量几乎是一致的。     

Effects of pH on Nonenzymic Browning during Storage in Apple Juice Concentrate Prepared from Bramley's Seedling Apples

In Bramley's Seedling, adjustment of juice pH affected darkening in apple juice concentrate during storage in the order pH 2.0 > pH 3.0 > pH 4.0. Darkening was also greater in model systems corresponding to juice at pH 3.0 compared with pH 4.0. The rapid darkening in concentrate of this cultivar appeared to be due to high rates of Maillard browning reactions rather than to other forms of nonenzymic browning.     

物料含水量和机筒温度对双螺杆挤压人参制品褐变效果的影响

以人参粉为原料,利用双螺杆挤压机制备挤压制品,研究物料含水量和机筒温度对褐变效果的影响。结果表明,随着机筒温度(100、120、140℃)的升高色度L 值减少,a 值增加;同样的温度条件下,物料含水量高L 值增加,a 值减少;b 值在挤压温度120℃时呈最高。人参在挤压过程中随着褐变度的增加还原糖含量也增加,而淀粉含量减少。在挤压温度相同条件下,物料含水量低氨基态氮消耗量增加。从颜色变化看人参双螺杆挤压制品优于传统红参。     

Browning and Amino Acid Loss in Model Total Parenteral Nutrition Solutions

The kinetics of browning and amino acid loss due to the Maillard reaction was studied in model total parenteral nutrition (TPN) systems containing glucose and either lysine, tryptophan, and cysteine alone or in combination. Cysteine systems showed the highest molar rate of browning while lysine showed the slowest rate. The molar rate of browning with all amino acids combined was significantly less than that of the sum of the individual rates, indicating interactions or inhibition. TPN electrolytes had no significant effect on the browning rate. The amino acids showed an initial rapid pseudo-first-order decrease in concentration followed by an apparent recovery and stabilization at an equilibrium concentration of about 60-80% of the original level.     

Combined Effects of Temperature,pH and Water Activity on Predictive Ability of Microbial Kinetic Inactivation Model

It is well known that temperature is the key factor controlling the microbial survival/inactivation. However, the interactive effects of further stressing environmental conditions may influence microbial behaviour. The objective of this work was to include, in the inactivation model, temperature, pH and a_w effects using a black box polynomial model, aiming at accurate prediction. Data of Listeria innocua obtained within the temperature range of 52.5 and 65.0 °C, pH of 4.5, 6.0 and 7.5, and a_w of 0.95 and 0.99 were used for model assessment. The relations of such parameters with temperature, a_w and pH were assumed to be polynomials.     

亚临界水体系中几种氨基酸的自降解反应

在亚临界水体系中对几种常见且具有代表性结构的氨基酸自降解行为进行研究,探讨pH对氨基酸自降解生成挥发性物质的影响及氨基酸降解机理。结果表明：由于甘氨酸（Gly）、L-丙氨酸（Ala）、L-精氨酸（Arg）、L-天冬氨酸（Asp）结构简单且热稳定性较好,在亚临界水体系中不会发生降解反应;L-丝氨酸（Ser）和L-苏氨酸（Thr）在亚临界水体系中,可通过脱羧生成中间体氨基乙醛母体,继而生成各种吡嗪类衍生物,其中包括2,3,5-三甲基吡嗪、3,5-二甲基-2-(3-甲基丁基)吡嗪和3,6-二甲基-2-乙基吡嗪等;L-苯丙氨酸（Phe）在亚临界水体系中主要生成苯甲醛、苯乙醛、苯乙酮和7-乙基-1,3,5-环庚三烯等;L-半胱氨酸（Cys）自降解会生成关键中间体巯基乙醛,再通过与各种小分子醛相互作用生成噻吩、噻唑类化合物和多硫化物。根据各体系中挥发性物质生成情况,提出了各氨基酸在亚临界水体系中挥发性物质可能的生成机制。     

Model for Combined Effects of Temperature, pH and Water Activity on Thermal Inactivation of Bacillus cereus Spores

Initially, the effect of water activity (a_w) on heat resistance of Bacillus cereus spores (decimal reduction time) was investigated. A linear relationship was found between log D and 1-a_w. The combined effects of temperature (85-105°C), pH (4.5-6.5) and water activity (0.80-1) were then studied. A four parameter model was fitted to the data. This model appeared to be parsimonious with each parameter having a biological significance. Interactions between factors were observed but they accounted for <2.4% of the total variation and they were not taken into account by the model.     

干燥鸡胸肉褐变原因分析及褐变程度的测定

分析干燥鸡胸肉在储藏过程中褐变的机理,建立采用分光光度计测定褐变程度的方法。该方法使用热碱溶液裂解蛋白质分子,使其释放出美拉德反应产物类黑素,将蛋白质和氨基酸等物质沉淀分离,然后采用分光光度计测量类黑素溶液在波长420nm处的吸光度(A420nm),用A420nm判定鸡胸肉的褐变程度。该方法简单快捷,能够鉴别出产品微小的褐变程度差异,具有较高的灵敏度。     

绿茶氨基酸对滋味的影响

对绿茶17种氨基酸与滋味进行了简单相关、多元逐步回归和主成分分析。结果表明：应用多元逐步回归分析建立的氨基酸与绿茶滋味数学模型,在本试验条件下,模型拟会非常有效。还就绿茶滋味的化学评价进行了讨论。     

Nonenzymatic Browning in Aseptically Packaged Orange Drinks: Effect of Ascorbic Acid, Amino Acids and Oxygen

Nonenzymatic browning of single strength orange juice and synthetic orange drinks containing 10% (v/v) orange juice has been studied under aerobic and anaerobic conditions. The juice and drinks were aseptically packaged into two types of flexible film (retort pouch and polyethylene Whirl-Park) and stored at 20 wk at 24°C. Ascorbic acid retention was affected by the processing itself, the concentration of added amino acids, and by the packaging material. The effect of amino acids on browning was found to be linear with concentration and was more pronounced in the presence of high levels of ascorbic acid.     

Effects of Hot Water Treatments on Antioxidant Enzymatic System in Reducing Flesh Browning of Persimmon

The flesh browning that appears during commercialization period is the main postharvest disorder that is limiting the market of “Rojo Brillante” persimmon in the Mediterranean area. Previous studies have suggested that mechanical damage suffered by the fruit during packing line operations is the trigger of this alteration when fruit is previously subjected to the required deastringecy treatment. In the present work, the effect of hot water treatments (HWTs) on flesh browning incidence of Rojo Brillante persimmon has been investigated. For that, fruits submitted to the commercial deastringency treatment were hot water treated at 45 °C for 30 min or 50 °C for 20 min and then subjected to different intensity of mechanical damage in packing line. Fruit bathed at 25 °C for 25 min and fruit hand-packed acted as control treatments. Our results confirmed that mechanical damage during packing is a decisive factor in the incidence of flesh browning, and this alteration is found to increase the damage intensity. HWTs significantly alleviated flesh browning disorder by affecting the antioxidative system enzymes; the activity of catalase and ascorbate peroxidase was increased by HWTs while the activity of peroxidases was reduced. No changes were observed in polyphenol oxidase and phenylalanine ammonia lyase activity. Therefore, the application of HWTs may be a useful postharvest technology to reduce flesh browning of persimmon induced by packing line operations.     

波动温度模拟蟹肉副溶血性弧菌生长模型

研究模拟蟹肉在4℃~28℃范围内副溶血性弧菌的生长动力学曲线,采用Belehradek方程描述温度对副溶血性弧菌的生长动力学影响。通过在设计的波动温度下模拟蟹肉中副溶血性弧菌的生长动态模型而得到预测值,并与在此波动温度下副溶血性弧菌的实测值进行比较,本文同时采用了偏差因子和准确因子来验证模型对波动温度的预测适用性。     

四种氨基酸和单糖美拉德模式反应体系的颜色特征和自由基清除活性

美拉德反应(Maillard reaction, MR)可以产生具有特征颜色并具有自由基清除活性的物质。以木糖-甘氨酸、木糖-丙氨酸、木糖-天冬氨酸、葡萄糖-甘氨酸为四个反应体系,在30℃和60℃条件下研究比较其美拉德反应产物（Maillard reaction products, MRPs）的颜色、吸收光谱特征及自由基清除活性。结果表明,木糖-甘氨酸MRPs有特征性颜色出现,对大约570nm和630nm波长的可见光有较强吸收,并且这一特征在30℃加热条件下更为明显。而其他三组MRPs无此特征。四个反应体系的60℃ MRPs较30℃ MRPs有更强ABTS自由基清除活性,且在两个加热条件下,木糖-甘氨酸和木糖-丙氨酸MRPs均比另外两组体系的活性更强。     

析因设计探究温度与水分活度对美拉德反应模型的影响

为改善美拉德反应风味,采用析因试验设计,探究115、120、125 ℃反应温度和0.85、0.80、0.75水分活度对基于猪肉酶解物的葡萄糖-半胱氨酸美拉德反应模型感官色泽风味、褐变程度、电子鼻信号值的影响。结果表明,温度对美拉德反应模型感官色泽、焦糊风味以及褐变程度均有极显著影响(P<0.01),水分活度对美拉德反应模型感官色泽和褐变程度有极显著影响(P<0.01),且两者对反应模型感官色泽、焦糊风味以及硫刺激风味都有显著性的交互作用(P<0.05),对模型褐变程度有极显著交互作用(P<0.01)。除醇类物质信号值只受温度影响(P<0.01)外,温度和水分活度对模型产生的甲基类、长链烷烃类、无机及有机硫化物类风味物质都有极显著的影响(P<0.01),以及极显著的交互作用(P<0.01)。从感官评分结果可得当温度为120 ℃、水分活度为0.75时,葡萄糖-半胱氨酸美拉德反应色泽和风味评分综合最优。故温度和水分活度及其交互作用与美拉德反应模型的色泽、风味存在密切关系。     

必需氨基酸对人体健康的影响

人体需要从食物中摄取的8种必需氨基酸为：异亮氨酸、亮氨酸、赖氨酸、蛋氨酸、苯丙氨酸、苏氨酸、缬氨酸、色氨酸。人体对每种必需氨基酸的需要是有一定数量和比例要求的，食品中任何一种必需氨基酸的量过多或过少，均会造成人体所需氨基酸之间出现新的不平衡，甚至会产生体内负氮平衡，长期下去，可影响到机体的生理机能，导致代谢紊乱、机体抵抗力下降等。动物性蛋白质食品中含有人体必需的8种氨基酸，其构成比例与人体所需的比例基本一致，不含有限制氨基酸；而植物性蛋白质食品中，8种必需氨基酸构成比例则不然，含有某种限制氨基酸。解决的方法通常有：一是适当食用含有必需氨基酸强化的食品；二是适当食用一些全蛋白食品；三是合理调整膳食，荤素搭配，粗细结合，取长补短。