Browning Inhibition in Fresh-cut'Fuji'Apple Slices by Natural Antibrowning Agents

ABSTRACT Response surface methodology was used to study the effect of antibrowning agents (4‐hexylresorci‐nol, glutathione, N‐acetylcysteine, and ascorbic acid) and storage time (14 d) on the color of minimally processed Fuji apples. The selected color parameters were L*,a*, b*, hue angle (h*), and color difference (ΔE*). Storage time had a significant effect on all the studied color parameters (P± 0.05). 4‐hexylresorcinol showed the most effective individual effect on keeping constant a*values (P± 0.0001). Besides, the interaction of N‐acetylcysteine/ glutathione was found to have a significant effect (P± 0.05) on maintaining a* values over time. On the other hand, individual treatment with N‐acetylcysteine in concentrations higher than 0.75% w/v may be used to preserve a*and h*.According to the F‐test, 4‐hexylresorcinol and N‐acetylcysteine (P± 0.05) displayed a significant individual effect on ΔE*, indicating that ΔE* decreased when increasing the concentration of these antibrowning agents. Nevertheless, color difference went down when 4‐hexylresorcinol concentration increased up to 0.5%, but higher concentrations of this agent led to an increase in ΔE* that indicates browning.     

紫薯中多酚氧化酶活性的研究及褐变控制

研究紫薯组织中多酚氧化酶(PPO)的活性,最适pH值、最适温度等特性,并在此基础上,研究加热温度、加热时间、抗坏血酸和柠檬酸添加量对PPO褐变的抑制效果。结果表明：紫薯PPO最适pH值范围为5.5～7.5,最适温度为30℃。在较好的分离淀粉的前提下,最佳抑制褐变条件是：加热温度80℃、加热时间10min、抗坏血酸添加量0.9‰、柠檬酸添加量1.2g/L。     

可食性涂膜包装对鲜切马铃薯褐变抑制的研究

选用卡拉胶、壳聚糖、海藻酸钠为主要原料作为涂膜原料,对马铃薯进行涂膜处理。低温下冷藏,分别对马铃薯进行褐变度、色差值、多酚氧化酶活性及感官色泽测定。并与马铃薯护色剂处理作对照,以比较其褐变抑制效果。     

红茶菌液对鲜切马铃薯褐变的影响

实验研究红茶菌液对鲜切马铃薯褐变的影响。在贮藏过程中对鲜切马铃薯的硬度、L*值、VC含量和多酚氧化酶活力变化进行测定。结果表明：红茶菌液能明显抑制鲜切马铃薯多酚氧化酶活力,能明显保持鲜切马铃薯VC含量,对保持鲜切马铃薯硬度有一定作用,对鲜切马铃薯L*值影响不大。初步证实了红茶菌液对鲜切马铃薯具有防褐变效果,且其效应因子是由红茶汤液经红茶菌发酵后带来的。     

鲜切马铃薯褐变发生机理及其控制方法研究进展

随着人们生活水平的提高,鲜切果蔬凭借自身的优势开始进入人们的视线,鲜切马铃薯由于其丰富的营养和方便性被人们广泛应用。鲜切马铃薯在去皮和切割过程中,细胞组织结构会受到损伤,引发一系列的生理代谢变化,这些变化对马铃薯的品质质量及色泽都产生很大影响,最主要的是切割会诱导酶促褐变反应的快速发生,使鲜切马铃薯的外观品质迅速降低。本文综述了鲜切马铃薯褐变发生的机理,同时对国内外控制鲜切马铃薯褐变技术的方法进行归纳,总结了物理、化学等不同方法的研究进展并提出相应建议,为后续鲜切马铃薯的研究提供参考。     

Browning Inhibition and Textural Changes of Pre-Peeled Potatoes Caused by Anaerobic Conditions

Sulphite treatment is often used for inhibition of enzymatic browning of pre-peeled potatoes. Introduction of CO₂ or N₂ gases in the immersion water was investigated as an alternative to sulphite. The samples were stored at 4 °C. Daily introduction of the gases reduced the O₂ content from approx. 8.8 mg/L (measured at 20 °C) to 0.2-1.9 mg/L during the immersion period. The CO₂ treatment inhibited the browning completely and N₂ treatment did not. It is assumed that this is due to the lower pH in the CO₂ water. When CO₂ was added only one time at the start of the experiment, it also inhibited discoloration, but the immersion water developed a weak brown colour. Both the CO₂ and the N₂ treatment induced hardening in the outer potato tuber tissue after cooking after 4-7 d of storage, as did Na₂SO₃ solutions.     

复合抑制剂对菊芋酶促褐变的影响

采用磷酸盐缓冲液提取菊芋中的多酚氧化酶(PPO),并对其酶学特性进行研究。结果表明,菊芋多酚氧化酶最适温度50℃、最适pH 值为4.0 和8.0。动力学实验表明菊芋PPO 的米氏常数Km 39.27mmol/L、最大反应速率Vmax 为1.369U/min。通过响应面试验设计对菊芋酶促褐变的抑制剂配方进行优化,结果表明：用质量度0.02g/100mL 乙二胺四乙酸二钠(EDTA)、0.02g/100mL 柠檬酸亚锡二钠和0.04g/100mL 的抗坏血酸复合溶液浸泡30min,能有效防止菊芋在加工期间的酶促褐变。     

Modeling the Contribution of Sugars, Ascorbic Acid, Chlorogenic Acid and Amino Acids to Non-enzymatic Browning of Potato Chips

The contribution of potato constituents to color development in fried chips was evaluated using model systems. Soluble constituents of potato slices were removed using water and ethanol. Leached slices were infiltrated with pH 6.2 solutions containing sucrose, reducing sugars (glucose and fructose), ascorbic, chlorogenic and amino acids (asparagine and glutamine) in quantities typical for potatoes. Infiltrated slice composition was evaluated by HPLC. Slices were fried and the color measured. Reducing sugars showed linear association with L* and hue angle and quadratic relationship with chroma of chips. Ascorbic acid affected chip color at low reducing sugar levels (40 mg/100g tuber); sucrose also contributed to chip color development.     

稳定态二氧化氯对鲜切马铃薯贮藏性及酶褐变的初步研究

本文对不同浓度二氧化氯（ClO2）对鲜切马铃薯褐变和贮藏性的影响进行了研究。实验结果表明ClO2处理时间越长效果越好,浓度却不一定越大越好。不同浓度二氧化氯（ClO2）处理均对PPO和POD酶产生抑制作用,其中二氧化氯240mol／L处理10min、360mol／L处理5min和360m01／L处理10min处理效果最好;马铃薯的PPO、POD活性很高且两者之间具有相关性,与褐变度数值相吻合：经过不同浓度二氧化氯（ClO2）处理的样品之间蛋白质含量有差异,但不太明显。     

鲜切甘薯不同部位褐变机理差异

以‘渝薯17’甘薯为实验材料,将鲜切甘薯分为皮部、周边以及中心3 个部位。通过对冷藏过程中鲜切甘 薯不同部位褐变情况、褐变底物酚类物质含量、褐变相关酶活力的比较研究,探讨鲜切‘渝薯17’不同部位的褐变 机理及差异。结果表明,绿原酸是甘薯褐变的主要底物,鲜切甘薯不同部位褐变存在差异,皮部褐变最严重,周边 次之,中心最弱。皮部总酚和游离酚含量均显著高于周边和中心组织（P＜0.05）,其中主要底物绿原酸含量为周 边和中心组织的3～4 倍。多酚氧化酶（polyphenoloxidase,PPO）是引起皮部组织褐变的主要酶,苯丙氨酸解氨酶 对酚类物质的积累起促进作用;周边组织褐变由PPO和过氧化物酶（peroxidase,POD）协同作用催化;中心组织 褐变则主要由POD引起。     

Inhibition of Browning on Fresh-cut Pear Wedges by Natural Compounds

ABSTRACT: Mechanical operations such as peeling and cutting during minimal processing involve enzymatic browning of fruit tissue. The objective of this work was to evaluate the individual and combined effects of N-acetyl-L-cysteine, reduced glutathione, ascorbic acid, and 4-hexylresorcinol to control pear browning. Browning of fresh-cut pears was prevented by a minimum concentration of 0.75% N-acetyl-L-cysteine up to 28 d at 4°C. Reduced glutathione treatments were also effective along the storage time although browning was observed after 21 d of storage with a dip of 0.75% reduced glutathione. However, ascorbic acid or 4-hexylresorcinol treatments did not seem to completely prevent browning of pear wedges throughout the storage period. An enhanced antibrowning effect was observed when combining both N-acetyl-L-cysteine and reduced glutathione, considering hue angle as color change index. Thus, hue angle reached maximum levels at 1.5% N-acetyl-L-cysteine (NAC) or 1.5% glutathione (GSH) and 1% NAC with 1% GSH for 28 d. Besides, N-acetyl-L-cysteine, reduced glutathione and 4-hexylresorcinol completely inhibited polyphenol oxidase activity as well as browning inhibitors slightly reduced firmness of fresh-cut pears.     

热处理对鲜切马铃薯褐变及挥发性物质的影响

褐变是影响鲜切马铃薯贮藏品质的重要因素之一。该研究探讨45、50℃热处理1～4 min对鲜切马铃薯褐变和挥发性风味物质的影响,以期为鲜切马铃薯品质保持提供调控技术和理论依据。45、50℃热处理4 min鲜切马铃薯在室温下2 h就观察到轻微的褐变,L*值下降10.51%、14.96%;a*值上升2.74、3.84,而45、50℃热处理1～3 min组鲜切马铃薯6 h内均未观察到褐变现象。与对照组相比,45℃热处理1～3 min组鲜切马铃薯硬度无显著变化,而其余热处理组硬度显著降低;两种温度1～3 min热处理组鲜切马铃薯苯丙氨酸解氨酶（PAL）、过氧化物酶（POD）酶活性和总酚含量分别降低了27.81%～33.68%、18.33%～50.37%、6.22%～28.92%。45℃热处理1～3min和50℃热处理1～2min热处理组较好的维持鲜切马铃薯原有的挥发性风味物质。总的来说,45、50℃热处理1～3 min可有效的抑制鲜切马铃薯褐变;其中,45℃热处理3 min抑制马铃薯褐变的同时较好维持了硬度、色泽、抗坏血酸含量和挥发性风味物质。     

美拉德反应产物抑制冷冻甘薯片的褐变

氨基酸与葡萄糖形成的美拉德反应产物（MRPs）对甘薯中的多酚氧化酶（PPO）以及冷冻甘薯片的褐变均具有一定的抑制作用.氨基酸与葡萄糖在不同的反应条件下（氨基酸的种类、pH值、反应时间以及氨基酸与葡萄糖之比）所形成的美拉德反应产物对甘薯中多酚氧化酶的抑制作用不同.其最佳的美拉德反应条件是反应pH值为3.0,L-半胱氨酸,氨基酸与葡萄糖的质量比为1：2,反应时间为5 h.     

柿子醋贮藏期间褐变及其抑制方法

研究柿子醋褐变原因及抑制其褐变方法。利用分光光度计和色差法分析柿子醋在贮藏期间总酚含量、多酚氧化酶(polyphenol oxidase,PPO)和过氧化物酶(peroxidase,POD)活性以及褐变度的变化,并研究几种抑制剂(NaCl、柠檬酸和L-抗坏血酸)对其褐变抑制的影响。结果表明：柿子醋贮藏期间发生的褐变主要是由于PPO和POD催化氧化总酚类物质引起的酶促褐变。不同质量浓度的褐变抑制剂NaCl、柠檬酸和L-抗坏血酸均显著维持醋液中较高的总酚含量,抑制PPO和POD活性,从而降低褐变度,减缓褐变发生,其中以0.24g/100mL NaCl、溶液1.2g/100mL柠檬酸和0.48g/100mL L-抗坏血酸对柿子醋抑制效果较好。     

Industrially processed vacuum-packed peeled Kennebec potatoes: process optimization, sensory evaluation, and consumer response

To optimize the processing and storage of Kennebec potatoes for sale in peeled, vacuum-packed ready-to-cook form, we studied the effects of blanching, various anti-browning solutions, and storage temperature. Unblanched potatoes pretreated with a mixture of 1% ascorbic acid and 0.5% citric acid, and stored at 2 °C, were found to have a shelf life of at least 1 mo without browning. Potatoes so treated differed sensorially from fresh potatoes, but were well received by consumers. PRACTICAL APPLICATION: The process described here maintains the characteristics of fresh potato with all the amenities of a processed product.     

Kinetic Study of Antibrowning Agents and Pressure Inactivation of Avocado Polyphenoloxidase

Pressure inactivation at room temperature (25 °C) of avocado polyphenoloxidase (pH 5.0) in absence or presence of 10 mM ethylene diaminetetraacetic acid (EDTA), NaCl, or benzoic acid or 0.05 mM 4-hexylresorcinol or glutathione could be described by a fractional conversion model. There appeared to be a resistant enzyme fraction (∼10% to 20%), necessitating about 825 MPa for inactivation in absence of antibrowning agents. EDTA addition resulted in sensitization of the pressure-sensitive enzyme fraction, which was attributed to the acid effect. Benzoic acid or NaCl addition resulted in a marked stabilization, whereas addition of glutathione resulted only in a minor stabilization of the pressure-sensitive enzyme fraction. 4-Hexylresorcinol displayed a sensitizing effect below and a stabilizing effect above 700 MPa. The pressure dependency of the inactivation rate constant was altered (p < 0.05) by addition of 4-hexylresorcinol or benzoic acid.     

不同熟化方法对紫色马铃薯挥发性风味物质形成的影响

利用顶空固相微萃取和气相色谱质谱联用技术,对不同熟化方式的2种紫色马铃薯(杭引1号、紫罗兰)挥发性风味物质进行分析,结果表明:1)癸醛为蒸熟马铃薯主体挥发性风味化合物;癸醛,香叶基丙酮为煮熟马铃薯主体挥发性风味物质,微波烘烤的马铃薯主要挥发性风味物质有香叶基丙酮、2,2,4-三甲基-1,3-戊二醇二异丁酸酯;烘烤马铃薯主要挥发性风味物质有癸醛、香叶基丙酮、2,4-二叔丁基苯酚、1-吡咯烷-1-环己烯。2)熟化加热方式的不同,马铃薯产生的挥发性风味化合物的种类丰富程度也不同,烘烤熟化处理马铃薯产生的挥发性风味物质种类最丰富,分别为8种(杭引1号)、21种(紫罗兰);微波烘烤马铃薯检测出挥发性风味物质种类最单调,分别为2种(杭引1号)、4种(紫罗兰)。3)2个品种之间既有共有风味物质,又有独有的风味物质。     

不同贮藏温度下鲜切紫甘薯褐变相关因素研究

为研究鲜切紫甘薯的褐变条件与机理,本文对不同贮藏温度下(4和12℃)的鲜切紫甘薯的褐变程度、褐变相关酶活力以及褐变底物酚类物质进行分析。结果表明,12℃贮藏组的鲜切紫甘薯褐变度始终显著高于4℃贮藏组(P<0.05)。贮藏期间,褐变重的鲜切紫甘薯多酚氧化酶(Polyphenol oxidase,PPO)和过氧化物酶(Peroxidase,POD)活性更高,丙二醛(Malondialdehyde,MDA)含量更多。2~8 d,不同贮藏温度下鲜切紫甘薯绿原酸和阿魏酸含量显著不同(P<0.05),因此推断褐变相关酶活性、膜脂过氧化程度以及酚类物质含量可能是引起鲜切紫甘薯褐变的关键因素。通过相关性分析,多酚氧化酶(PPO)和过氧化物酶(POD)是引起鲜切紫甘薯褐变的关键酶。绿原酸和阿魏酸是鲜切紫甘薯褐变的主要底物。     

影响芦荟制品非酶褐变的因素及其控制方法

利用分光光度法测定芦荟制品加工和贮存过程中褐变指数的变化 ,结果表明 ,影响芦荟制品非酶褐变的主要因素有 :多酚类物质的质量浓度、pH、环境温度、Mg2 +、Fe3+、Cu2 +等金属离子以及包装材料的质量 ;控制这些因素可有效抑制芦荟制品的非酶褐变 .