一氧化氮缓释熏蒸处理对鲜切苹果片品质的影响

本文研究一氧化氮(nitric oxide,NO)气体缓释熏蒸处理对鲜切苹果片品质变化的影响。以红富士苹果为试材,将鲜切苹果片与NO供体二乙烯三胺一氧化氮聚合物(diethylenetriamine/nitric oxide,DETANO)、柠檬酸及玉米淀粉制成的NO气体缓释剂共置于密闭容器中,在4℃条件下贮藏。贮藏期间测定鲜切苹果片的表面明度(lightness,L*)值、果肉硬度、失重率、总酚含量、多酚氧化酶(polyphenoloxidase,PPO)活性、可溶性固形物含量、维生素C含量以及可滴定酸含量。结果表明:与对照组相比,NO气体缓释熏蒸处理能有效减轻鲜切苹果片的表面褐变、果肉软化和失重,显著抑制总酚含量的下降和PPO活性的升高,并保持可溶性固形物、维生素C和可滴定酸含量,延缓鲜切苹果片的品质劣变,为鲜切苹果片的贮藏保鲜提供了一种新方法。     

一种可食膜对鲜切苹果的生理及品质的影响

以红富士苹果为原料,研究一种复合性可食涂膜对鲜切苹果的保鲜效果,考察了呼吸强度、多酚氧化酶(PPO)的活力、游离酚含量、硬度、可溶性固形物含量(SSC)和维生素C(VC)含量等生理和品质指标。结果表明:使用该复合膜能显著降低鲜切苹果的呼吸强度,抑制PPO的酶活力,在游离酚增加的情况下仍显著抑制鲜切苹果的酶促褐变;用复合膜处理的鲜切苹果,硬度与对照基本一致,保持较对照组更高的SSC、VC和游离酚含量,使产品保持较好的外观、营养和质地等品质。     

苹果多酚处理对鲜切芋艿品质的影响

为了控制鲜切芋艿贮藏过程中的褐变并延长其货架期,研究（10.0±0.5）℃条件下,蒸馏水（CK）和不同质量分数（0.3%、0.5%、0.7%）苹果多酚浸泡处理对其色泽、硬度、糖类物质含量、总酚含量、丙二醛含量及褐变相关酶活力的影响。结果表明：苹果多酚处理能够延缓芋艿切片贮藏过程中的褐变进程,其中以0.5%苹果多酚处理的效果最佳;与CK组相比,0.5%苹果多酚处理可以保持芋艿切片较好的色泽和较高的硬度,延缓苯丙氨酸解氨酶活力和总酚含量的升高,抑制芋艿过氧化物酶、多酚氧化酶、脂氧合酶活力和丙二醛含量的升高,从而延缓鲜切芋艿贮藏过程褐变的发生,保持鲜切芋艿较好的贮藏品质。     

柠檬酸处理对鲜切苹果的保鲜效果

为研究柠檬酸处理对鲜切苹果品质的影响,将鲜切‘寒富’苹果分别放入0.5%、1.0%、1.5%柠檬酸溶液中浸泡2 min后沥干,用0.11 mm厚度的聚乙烯保鲜膜包装后置于4 ℃冷库中贮藏,每2 d检测与成熟衰老相关生理生化指标。结果表明,适当质量分数的柠檬酸处理可保持苹果切块的感官品质,延缓营养物质的下降,抑制微生物的繁殖,对鲜切苹果有较好的护色效果;1.5%柠檬酸溶液浸泡处理能在8 d贮藏期内4 ℃冷藏条件下保持着鲜切苹果的良好品质,能有效延迟果肉褐化进程,降低褐变程度,抑制硬度和可溶性固形物、可滴定酸及抗坏血酸含量的下降,并能延缓相对电导率和丙二醛含量的上升,降低多酚氧化酶、过氧化物酶的活性。     

柠檬酸亚锡二钠对鲜切莲藕护色作用的研究

柠檬酸亚锡二钠(DSC)是一种新型护色剂。将DSC用于鲜切莲藕预处理阶段,抑制莲藕多酚氧化酶活力及褐变,探讨影响DSC对鲜切莲藕片护色作用的因素,并与其他常用护色剂的护色效果进行对比。结果表明:DSC对鲜切藕产品低温保藏期间的褐变和多酚氧化酶活力都有很好的抑制作用,在pH 3～6条件下用0.05%～0.2%DSC浸泡液处理15min后,鲜切藕产品可保持较低的褐变度和多酚氧化酶活力,同时在4℃、20d内DSC的护色效果稳定;与其他常用护色剂比较,在0.1%的等量护色剂浓度下,DSC护色效果优于柠檬酸、抗坏血酸、异抗坏血酸钠,与亚硫酸氢钠效果相当。     

抗坏血酸、半胱氨酸与氯化钙复合处理对鲜切芋艿褐变的影响

研究抗坏血酸、半胱氨酸与氯化钙复合处理对于鲜切芋艿贮藏期间酶促褐变的控制效果及其机理。结果表明：切分后的芋艿片褐变度迅速上升,亮度（L*）值下降,苯丙氨酸解氨酶、脂氧合酶、多酚氧化酶和过氧化物酶活性升高,总酚积累。与对照相比,2.5%抗坏血酸＋0.05%半胱氨酸＋0.4%氯化钙浸泡处理能够有效降低鲜切芋艿贮藏期间的褐变度,保持较高的L*值和总酚含量,并抑制了苯丙氨酸解氨酶、多酚氧化酶、过氧化物酶和脂氧合酶活性和相对电导率的升高,达到提高鲜切芋艿贮藏品质和延长贮藏周期的目的。     

柠檬酸对鲜切莲藕酶促褐变的影响研究

研究柠檬酸处理的鲜切莲藕在4℃条件下贮藏15d期间,色差、整体感官质量(OVQ)、多酚氧化酶(PPO)活性、丙二醛(MDA)和总酚(TP)含量的变化。结果表明:与对照组相比,不同浓度的柠檬酸处理对鲜切莲藕的酶促褐变均有一定的抑制作用,且在本实验条件下,柠檬酸浓度越大,护色效果越好。对潜在机理的研究表明,1.5%的柠檬酸处理可显著降低鲜切莲藕中的PPO活性和MDA含量(p0.05),总酚含量在贮藏前期(0~3d)显著高于对照组(p0.05),柠檬酸对PPO和MDA的影响可能是其抑制鲜切莲藕酶促褐变的部分原因。本研究可为鲜切莲藕的保鲜护色提供一定的理论依据。     

复合保鲜剂对鲜切苹果贮藏品质的影响

以鲜切苹果为试材,研究不同浓度柠檬酸、壳聚糖及D-异抗坏血酸钠(D-sodium erythorbate,D-SE)复合保鲜剂处理5 min,4℃贮藏期间鲜切苹果贮藏品质特性的变化规律。结果表明:复合保鲜剂处理组可保持鲜切苹果感官品质、抑制鲜切苹果多酚氧化酶(PPO)及过氧化物酶(POD)活性,对鲜切苹果有较好的保鲜效果;1.0%柠檬酸+0.5%壳聚糖+1.0%D-异抗坏血酸钠溶液处理组优于其他处理组,能在4℃贮藏12 d内保持鲜切苹果外观品质与食用品质品质,有效抑制鲜切苹果果肉褐变,延缓硬度和TSS含量降低速率,降低与褐变有关的多酚氧化酶(PPO)及过氧化物酶(POD)活性。     

鲜切莲藕片的防褐变研究

按照采用均匀设计的要求，分别设计出以不同浓度的柠檬酸、抗坏血酸，氯化钙和焦磷酸钠的7种组合来处理鲜切莲藕。研究了莲藕在贮藏期间的褐变度、可溶性固形物、多酚氧化酶、总酚含量等指标的变化，确定出了0．2％柠檬酸＋0．7％Vc＋0．3％-0．4％氯化钙＋0．2％焦磷酸钠的组合，可以有效抑制鲜切莲藕的褐变，在5℃下货架期达16d。为鲜切莲藕的后续加工提供了依据。     

马齿苋提取物对鲜切苹果褐变的影响

酶促褐变是影响鲜切果蔬品质及商业价值的关键问题之一。为探究马齿苋提取物在果蔬保鲜方面的应用价值,以鲜切苹果为研究材料,采用质量分数0.05%马齿苋提取物溶液浸泡鲜切苹果5min,在(4±1)℃存放8d。以鲜切苹果的褐变指数、多酚氧化酶(polyphenol oxidase,PPO)活力、苯丙氨酸解氨酶(phenylalanine ammonia-lyase,PAL)活力、过氧化氢酶(catalase,CAT)活力、过氧化物酶(peroxidase,POD)活力、丙二醛(malondiadehyde,MDA)含量、抗坏血酸含量以及DPPH自由基清除能力为评价指标,分析马齿苋提取物对鲜切苹果褐变及贮藏品质的影响。结果表明:与蒸馏水对照组相比,马齿苋提取物溶液处理能有效抑制鲜切苹果的褐变程度,在降低POD、PPO和PAL活力方面也有明显效果,能够在保证膜完整性的基础上减少细胞膜出现的损伤。相关性分析表明:鲜切苹果的褐变指数与CAT活力、抗坏血酸含量、DPPH自由基清除能力呈现极显著负相关(P<0.01),与MDA含量、PPO活力、POD活力、总酚含量呈极显著正相关(P<0.01)。马齿苋提取物溶液处理的鲜切苹果抗褐变效果较好,同时贮藏后鲜切苹果的抗氧化能力也有一定提高。     

INFLUENCE OF CHEMICAL TREATMENT ON QUALITY OF CUT APPLE (cv. JONAGORED)

The quality of a new variety of apple, ‘Jonagored’, after peeling and cutting was evaluated during ten days of storage in air at 4C. The objective was to evaluate the shelf-life of apple cubes by detecting the limiting parameter and to test the influence of different chemical dips on the cut apple quality with the aim of extending shelf-life. Color, i.e. browning at the cut surface, was found to be the critical quality parameter determining the shelf-life of the cut apple to less than three days. There were no significant differences between the dip treatments in measurements of CIE values. When apple cubes were treated with ascorbic acid, ascorbic acid plus calcium chloride or ascorbic acid plus calcium chloride and citric acid, the 0.75% ascorbic acid dip was found to be the most effective preservation treatment in terms of reducing color change of the cut surface. Both 0.75% ascorbic acid and 0.75% ascorbic acid plus 0.75% calcium chloride inhibited the loss of firmness of apple cubes. When citric acid was added to the dip treatment, there were color changes similar to those of the control.     

曲酸处理对娃娃菜采后褐变的影响

为研究曲酸处理对娃娃菜茎部切口褐变的影响及其机制,本实验用0.05 g/L曲酸和超纯水（对照）分别浸泡娃娃菜茎部切口1 min,再在20 ℃、相对湿度90%的条件下贮藏5 d,每天取样分析其感官品质并测定呼吸强度、乙烯释放速率、总酚含量、类黄酮含量及褐变相关酶活力。结果表明：与对照相比,曲酸处理可以有效保持娃娃菜的感官品质,抑制娃娃菜茎部褐变,降低质量损失率、丙二醛含量,提高类黄酮以及总酚含量;抑制过氧化物酶、多酚氧化酶的活力,第5天时曲酸处理组过氧化物酶、多酚氧化酶活力分别比对照组低29.7%、28.5%;增强苯丙氨酸解氨酶、过氧化氢酶活力,第5天时曲酸处理组苯丙氨酸解氨酶、过氧化氢酶活力比对照组分别高1.0%、12.4%。结论：曲酸处理可以有效抑制娃娃菜茎部切口的褐变,保持娃娃菜商品性和营养品质,延长娃娃菜货架期。     

Biochemical changes of fresh-cut pineapple slices treated with antibrowning agents

The effectiveness of ascorbic acid (AA), isoascorbic acid (IAA) and N‐acetyl‐cysteine (AC) in inhibiting browning of fresh‐cut pineapple slices that were stored for up to 14 days at 10 °C, were studied. Slices treated with IAA and AA maintained higher levels of sugars and vitamin C than AC and controls. A low reduction of total phenolic content in treated slices was correlated with a lower polyphenol oxidase activity. IAA and AA slowed the degradation rates of sugars, vitamin C, and phenolic content, whereas AC was less effective in affecting these processes. A higher content of AA and IAA was associated with better compositional quality parameters and appearance of the pineapple slices during the storage period.     

POLYPHENOLOXIDASE ACTIVITY OF MINIMALLY PROCESSED 'JONAGORED' APPLES (MALUS DOMESTICA)

The influence of three chemical dips using ascorbic acid (AA), citric acid (CA) and calcium chloride (CC) on the polyphenoloxidase (PPO) activity and on the total phenolic content of minimally processed (MP) apple (Malus domestica, cv. Jonagored) during cold storage was evaluated and a potential relationship with enzymatic browning was investigated. An ascorbic acid dip (42.6 mM) of 5 min duration was the most efficient chemical treatment in reducing the PPO activity of apple cubes. A 92% inhibition was achieved after 7 days of storage at 4C. All treatments were advantageous in comparison to the control in reducing color changes. Color changes, determined by absorbance at 420 nm (soluble pigments) and lightness (L) (insoluble pigments) of apple cubes treated with ascorbic acid were correlated with total phenolic content. No correlation was observed between PPO activity and tristimulus color parameters, browning index or total phenolic content of AA‐treated apple cubes.     

乳酸菌发酵对梨汁的护色作用

梨汁在加工过程中极易褐变,乳酸菌发酵能有效保护梨汁的色泽。本研究测定梨汁发酵及储藏过程中色泽、多酚氧化酶活性、酚类物质、抗坏血酸含量等指标的变化,并与未发酵梨汁和添加柠檬酸的调酸梨汁对比,探索乳酸菌发酵对果蔬汁的护色机理。30天储藏期内,未发酵梨汁褐变指数从0.073变化至0.310,显著高于发酵梨汁(0.134);乳酸菌发酵作用有效抑制了多酚氧化酶的活性,使得发酵梨汁中的酚类物质的保存率(43%)显著高于未发酵梨汁(16%);发酵梨汁中抗坏血酸稳定性更高,保存率(85%)较未发酵梨汁高(50%),减少了非酶褐变。乳酸菌通过在梨汁中发酵产酸,抑制多酚氧化酶的活性,保存酚类、抗坏血酸等物质,从而保护梨汁色泽。     

Physiological and biochemical changes of different fresh-cut mango cultivars stored at 5 °C

Treatments to inhibit browning, decay and to extend shelf life of ‘Keitt’, ‘Kent’ and ‘Ataulfo’ mango cultivars as a fresh‐cut produce were investigated. Combinations of calcium chloride (CaCl₂), antioxidants [ascorbic acid (AA), citric acid (CA)] and two commercial film coatings resulted in a reduction of browning and deterioration of fresh‐cut mangoes stored at 5 °C, especially for the Ataulfo cultivar. The use of CaCl₂ + AA + CA significantly reduced colour deterioration, loss of firmness and did not affect sensory characteristics of fresh‐cut mango, with a larger effect in the Ataulfo cultivar. In general, these treatments prevented loss of sugar and vitamin C of cubes during storage at 5 °C. Shelf life of this cultivar was 21 days, while that of Keitt and Kent was only 9 and 12 days, respectively. There is a correlation between carotene and vitamin C content of Ataulfo mango and its longer shelf life compared with the other cultivars.     

Antibrowning and Antimicrobial Properties of Sodium Acid Sulfate in Apple Slices

ABSTRACT: There are few available compounds that can both control browning and enhance microbial safety of fresh‐cut fruits. In the present study, the antibrowning ability of sodium acid sulfate (SAS) on “Granny Smith” apple slices was first investigated in terms of optimum concentration and treatment time. In a separate experiment, the apple slices were treated with water or 3% of SAS, calcium ascorbate, citric acid, or acidified calcium sulfate for 5 min. Total plate count, color, firmness, and tissue damage were assessed during a 21‐d storage at 4 °C. Results showed that the efficacy of SAS in inhibiting browning of apple slices increased with increasing concentration. A minimum 3% of SAS was needed to achieve 14 d of shelf life. Firmness was not significantly affected by SAS at 3% or lower concentrations. Antibrowning potential of SAS was similar for all treatment times ranging from 2 to 10 min. However, SAS caused some skin discoloration of apple slices. When cut surface of apple slices were stained with a fluorescein diacetate solution, tissue damage could be observed under a microscope even though visual damage was not evident. Among the antibrowning agents tested, SAS was the most effective in inhibiting browning and microbial growth for the first 14 d. Total plate count of samples treated with 3% SAS was significantly lower than those treated with calcium ascorbate, a commonly used antibrowning agent. Our results suggested that it is possible to use SAS to control browning while inhibiting the growth of microorganisms on the apple slices if the skin damage can be minimized. Practical Application: Fresh‐cut apples have emerged as one of the popular products in restaurants, schools, and food service establishments as more consumers demand fresh, convenient, and nutritious foods. Processing of fresh‐cut apples induces mechanical damage to the fruit and exposes apple tissue to air, resulting in the development of undesirable tissue browning. The fresh‐cut industry currently uses antibrowning agents to prevent discoloration. However, the antibrowning solutions can become contaminated with human pathogens such as Listeria monocytogenes, and washing of apple slices with the contaminated solutions can result in the transfer of pathogens to the product. It would be ideal if an antibrowning compound prevented the proliferation of human pathogens in solutions and minimized the growth of pathogens during storage. The study was conducted to investigate antibrowning and antimicrobial properties of sodium acid sulfate (SAS) in comparison with other common antibrowning agents on Granny Smith apples. Results showed that among the antimicrobial agents we tested, SAS was the most effective in inhibiting browning and microbial growth for 14 d at 4 °C. However, SAS caused some skin discoloration of apple slices. Overall, SAS can potentially be used to inhibit tissue browning while reducing the microbial growth on apple slices. The information is useful for the fresh‐cut produce industry to enhance microbial safety of fresh‐cut apples while minimizing browning, thus increasing the consumption of the health benefiting fresh fruit.     

Effects of initial low oxygen and perforated film package on quality of fresh‐cut cabbages

The effects of perforated film packages (PFP) with different oxygen partial pressures (5, 8 and 10 kPa) and a barrier package (BP) at 21 kPa of O₂ on the quality of fresh‐cut cabbages were studied at 5 and 20 °C. The microbial growth, appearance, flavor, ascorbic acid content and polyphenol oxidase activity were determined during storage. The results indicated that fresh‐cut cabbages had better color retention and quality in PFP. Oxidation of ascorbic acid (AA) and browning of fresh‐cut cabbage were inhibited effectively using a PFP and an initial oxygen partial pressure equal to 5 kPa. Analysis of microbial growth also showed that the total count on fresh‐cut cabbage was relative lower in PFP with an initial low O₂ content. Loss of total ascorbic acid was much lower in PFP than that in BP by suppressing AA oxidation. The results of sensory evaluation showed that flavor and appearance were maintained effectively at 5 °C and significant differences in flavor were found between PFP and BP both at 5 and 20 °C, while significant differences in appearance were found between PFP and BP only at 20 °C. Copyright © 2007 Society of Chemical Industry     

精准温度处理对鲜切莲藕褐变、生理和品质的影响

为了明确精准温度处理对防褐变剂处理后鲜切莲藕褐变、生理和品质的调控作用,采用防褐变剂（质量分数1.0%无水柠檬酸+0.1%抗坏血酸钙+0.2% L-天门冬氨酸）处理鲜切莲藕,在相温（?0.5±0.1）℃、冰温（?0.5±0.3）℃和冷藏（4±1）℃的条件下贮藏,研究不同精准温度对鲜切莲藕表观色泽、褐变底物与相关酶活性、生理指标和营养品质的影响。结果表明,贮藏6 d时,精准温度（相温、冰温）处理可以延缓L*的降低、a*和褐变度的增加,抑制总酚的下降和褐变相关酶多酚氧化酶和过氧化物酶活性,其中相温贮藏维持鲜切莲藕原有色泽最佳。在贮藏过程中,精准温度（相温、冰温）处理能够抑制鲜切莲藕呼吸强度、乙烯生成速率、相对电导率和丙二醛含量上升,同时延缓鲜切莲藕还原糖的升高和V_C含量的下降。通过SPSS综合评分显示,相温组综合得分最高,主成分分析显示,相温组与多酚氧化酶、相对电导率、褐变度、丙二醛、a*的相关性较低。因此,相温贮藏更好地延缓鲜切莲藕贮藏期间褐变的发生并维持其品质。     

The effectiveness of ozone and acidulant treatments in extending the refrigerated shelf life of fresh-cut potatoes

Abstract: The objective of the study was to determine the effectiveness of acidulant dip treatments (with or without aqueous ozone) to reduce enzymatic browning and to extend the shelf life of fresh‐cut potato slices during refrigerated storage (4 °C) for 28 d. Potato slices subjected to aqueous ozone (2 ppm) had significantly (P≤ 0.05) higher L‐values and lower a‐values, but ozone did not appear to have any effect on aerobic plate counts (APCs) or polyphenol oxidase (PPO) activity. NatureSeal (NS) and sodium acid sulfate (SAS) were the most effective acidulant treatments in reducing browning (significantly [P≤ 0.05] higher L‐values, lower a‐values, and browning index values) regardless of ozone treatment. NS and SAS also had lower PPO activity compared to other treatments on days 0 and 28, and significantly (P≤ 0.05) lower APCs (≤2.00 log CFU/g) over refrigerated storage. Therefore, the SAS treatment was comparable to NS, a commercially available product, and showed promise as an effective antibrowning dip to reduce browning and spoilage in fresh‐cut potato products. Practical Application: A 1% SAS dip treatment which included 1% citric and 1% ascorbic acid was found to be an effective antibrowning dip for fresh‐cut potatoes along with NatureSeal®'s PS‐10, compared to other treatments. They were both effective in maintaining low microbial counts over refrigerated storage. Additionally, aqueous ozone washes (2 ppm) showed significant benefits to reduce browning; however, ozone did not affect microbial counts or PPO enzyme activity. Therefore, the SAS treatment could have potential use in the fruit and vegetable industry to reduce browning and spoilage in fresh‐cut potato products.