复合保鲜剂对鲜切山药保鲜效果的影响

为了延缓鲜切山药的褐变和品质劣变,延长保鲜期。从洋葱中提取洋葱油,结合保鲜剂柠檬酸和壳聚糖,以色差L*值和感官评分为考察指标,在单因素试验的基础上进行正交试验,筛选适合鲜切山药保鲜的复合保鲜剂配方。结果表明:鲜切山药最佳保鲜剂组合为0.6%洋葱油+1.0%柠檬酸+1.0%壳聚糖,与清水处理相比,该组合可显著抑制鲜切山药贮藏过程中多酚氧化酶(PPO)和过氧化物酶(POD)的活性,降低鲜切山药的相对电导率和丙二醛(MDA)含量,延缓失重和软化,保持鲜切山药的亮度和总酚含量,维持鲜切山药可溶性固形物和还原糖含量,且具有较好的感官品质。与对照组相比,该复合保鲜剂可使鲜切山药保鲜期延长6d左右。     

海藻酸钠涂膜对鲜切芋艿保鲜效果的影响

为了延缓鲜切芋艿的褐变和品质劣变,延长其保鲜期。以芋艿为原料,在(10±1)℃的贮藏条件下,研究不同浓度海藻酸钠涂膜对鲜切芋艿营养品质和酶活性的影响。结果表明:与对照组相比,不同浓度海藻酸钠涂膜可降低鲜切芋艿贮藏过程中多酚氧化酶和过氧化物酶的活性,显著抑制鲜切芋艿的褐变,减少淀粉、可滴定酸和维生素C的降解,延缓失重,维持可溶性糖和还原糖的含量,保持鲜切芋艿的营养品质。其中以2%海藻酸钠涂膜处理效果较好,与对照组相比可延长保鲜期4 d。     

淀粉/纳米TiO_2涂膜对鲜切山药保鲜效果的研究

以鲜切山药为保鲜对象,研究淀粉/纳米TiO_2涂膜对其的保鲜效果。将鲜切山药涂膜后在10℃贮藏,通过测定鲜切山药在贮藏过程中失重率、色泽、褐变、可溶性固形物含量、丙二醛含量、PPO和POD活性指标的变化,评估鲜切山药在贮藏期间的品质变化。结果表明:该涂膜能有效减少鲜切山药水分的散失和可溶性固形物含量的降低,抑制色泽变化和褐变,减少MDA的产生,抑制PPO和POD活性的升高。淀粉/纳米TiO_2涂膜能有效保持鲜切山药的品质,在鲜切山药保鲜上具有潜在的应用价值。     

壳聚糖精油复合涂膜对鲜切山药保鲜的应用

研究壳聚糖结合2种植物精油复合涂膜对鲜切山药在低温贮藏期间的保鲜效果。分别采用0.3%的柠檬精油、肉桂精油和二者1:1混合精油与壳聚糖乳液复配,同时采用纯壳聚糖乳液和水处理作为对照,考察不同处理方式对鲜切山药失重率、腐烂率、Vc含量、总糖含量、多酚氧化酶(PPO)和褐变强度(BD)的影响。结果表明,不同组分的精油复合壳聚糖涂膜处理均能够有效降低山药水分、Vc等成分的流失,延缓鲜切山药的褐变强度和PPO活性。壳聚糖复合2种精油涂膜处理能够减缓鲜切山药营养成分的流失,从而延长其保存期。     

改性葛根淀粉涂膜对鲜切山药保鲜效果的影响

分别使用不同浓度的改性葛根淀粉膜液对鲜切山药进行涂膜处理并在(4±1)℃下保存,定期测量贮藏期间鲜切山药的腐烂率、菌落总数、电导率、颜色、失重率、可溶性固溶物含量等指标。结果表明:改性葛根淀粉涂膜处理能有效抑制鲜切山药的微生物生长及颜色褐变,减少水分损失,较好地保持品质和安全,以改性葛根淀粉膜液浓度为3%的保鲜效果最好,其贮藏期可比对照有效延长4~5 d。     

铁棍山药黏液复合乳液保鲜鲜切马铃薯研究

为了降低鲜切马铃薯在贮藏过程中的酶促褐变程度、减缓营养流失,延长货架期,该文从铁棍山药中提取山药黏液,并与山梨醇以及V C复配,制备鲜切马铃薯保鲜乳液;通过色差、失重率、还原糖、抗氧化酶活性和抗氧化物质含量等指标的变化,探讨山药黏液复配乳液对鲜切马铃薯的保鲜效果。结果表明,1%山药黏液与0.5%的甘油、0.75%D-山梨醇以及0.02%V C(均为质量分数)的复配乳液涂膜的鲜切马铃薯,在室温下贮藏6 d,能够显著降低马铃薯的表面褐变程度、减少失重率和还原糖累积、显著抑制多酚氧化酶(polyphenol oxidase,PPO)、过氧化物酶(peroxidase,POD)和苯丙氨酸解氨酶(phenylalnine ammonialyase,PAL)的活力,降低总酚和丙二醛(malondialdehyde,MDA)含量;Zeta电位和粒径分析表明该乳液具有较好的稳定性和分散性。因此,铁棍山药黏液可作为天然的鲜切果蔬保鲜剂,具有应用潜力。     

复合保鲜液对鲜切山药的护色保鲜作用

为改善鲜切山药的保鲜效果,以柠檬酸、抗坏血酸、L-半胱氨酸和NaCl对鲜切山药进行浸泡10 min处理,以褐变度为评价指标,在单因素试验的基础上,进行L9(34)正交试验设计,筛选出最佳复合保鲜液配方。通过理化指标和营养指标的测定,结果表明鲜切山药最佳复合保鲜液配方为1.5%柠檬酸+0.8%抗坏血酸+0.1%L-半胱氨酸+1.5%NaCl(质量分数)。以此配方进行试验验证,测得贮藏10 d的褐变度比对照组降低23%,该保鲜液能够保持鲜切山药的色泽,抑制多酚氧化酶、过氧化物酶和苯丙氨酸解氨酶酶活性,减少营养物质及活性分子尿囊素的损失,提高鲜切山药的商业价值,为鲜切山药提供一种简单有效的保鲜方法。     

生姜提取液对鲜切马铃薯贮藏品质的影响

以鲜切马铃薯为原料,探索不同浓度的生姜提取液对其贮藏品质的影响,试验采用0.05%、0.10%、0.50%和1.00%的生姜提取液浸泡鲜切马铃薯,以蒸馏水为对照,在4℃下贮藏5 d,通过测定失重率、褐变度、可溶性固形物含量、还原糖含量和多酚氧化酶(PPO)活性来综合评价生姜提取液的最佳浓度。结果表明,0.50%生姜提取液对鲜切马铃薯的贮藏品质维持最好。0.50%生姜提取液处理能显著降低鲜切马铃薯的失重率和褐变度,减缓还原糖的上升速率,减少了可溶性固形物的损耗,有效抑制了PPO活性,较好地保持了鲜切马铃薯的品质,延缓了鲜切马铃薯的褐变。因此,生姜提取液可以作为鲜切马铃薯的护色保鲜剂。     

不同涂膜处理对鲜切铁棍山药品质的影响

以壳聚糖和海藻酸钠为保鲜剂,对鲜切铁棍山药进行涂膜保鲜,每隔2d测定失重率、Vc含量、可滴定酸含量、褐变度、可溶性固形物含量、多酚氧化酶活性等指标研究保鲜效果。同时以空白组、壳聚糖涂膜组作为对照。结果表明:壳聚糖浓度为1.2%的单一膜和1.2%壳聚糖、0.2%海藻酸钠复合膜都能有效地抑制鲜切铁棍山药的褐变,降低失重率,减少营养物质的损失。复合膜的保鲜效果最好。     

微波对鲜切山药护色及品质的保持

分别使用不同微波功率100、300、500 W对鲜切怀山药进行80 s处理,并在(4±1)℃下保存,贮藏期间每3 d测定鲜切山药的亮度、褐变度、多酚氧化酶活性、过氧化物酶活性、电导率、水分含量、失重率和感官评价指标。结果表明,微波处理能够有效抑制鲜切山药的相关褐变酶多酚氧化酶(polyphenol oxidase,PPO)与过氧化物酶(peroxidase,POD)的活性,延缓整体褐变,维持山药乳白色泽,同时能维持细胞膜的完整性,但微波功率对护色效果有较大影响,功率不足会导致护色效果不显著,功率过高则会引起鲜切山药失水失重加剧,实验中以微波功率300 W、处理时间80 s的保鲜效果最佳,能很好地维持鲜切山药的色泽,且贮藏保鲜期可达到15 d。该研究为今后鲜切果蔬保鲜的研究提供了微波护色方向。     

Allicin Inhibits Microbial Growth and Oxidative Browning of Fresh-Cut Lettuce (Lactuca sativa) During Refrigerated Storage

Fresh-cut lettuce has a short shelf life since it is very perishable and susceptible to enzymatic browning. The aim of this study was to examine the effectiveness of allicin treatment in prolonging the shelf life of fresh-cut lettuce (Lactuca sativa L. var. angustana Irish). Fresh-cut lettuce slices were treated with water (control), 0.2 and 1 % of allicin solutions, respectively, and stored at 4 °C, >90 % relative humidity. Sensory parameters, microbiological indicators, and physiological indices were determined at 0, 2, 4, and 6 days of storage. The sensory analyses revealed that allicin inhibited the color change and maintained the visual quality of lettuce slice without impairing flavor. Allicin treatment delayed microbial growth at cold storage, as evidenced by the lowered total viable counts (decreased by 2.52 log cfu/g) and yeast and mold counts (decreased by 1.59 log cfu/g) after 6 days in 1 % allicin-treated samples compared to control samples. In addition, differences between lettuce treated with 1 % allicin and control slices in objective color (total color change, chrome, and hue angle), total phenolic compounds and quinones content, activities of browning-related enzymes, and antioxidative enzymes suggested that allicin had antioxidative properties. Conclusively, it was demonstrated for the first time that allicin effectively protected fresh-cut lettuce from tissue browning and microbiological spoilage. These findings indicate that allicin has great potential as a natural additive to extend the shelf life of fresh-cut lettuce.     

硫代乙酸糠酯对鲜切茄子褐变的抑制作用

为延缓鲜切茄子在贮藏过程中的酶促褐变并延长其货架期,以鲜切茄子为试材,研究了最适浓度硫代乙酸糠酯（Furfuryl thioacetate,FT）处理对鲜切茄子感官质量评价、褐变度、褐变相关酶活性、总酚和醌含量及总抗氧化能力的影响。结果表明：0.64 mmol/L FT处理可抑制在低温贮藏条件下鲜切茄子的褐变,较好地保持其总体感官质量,延长鲜切茄子货架期至第5 d。进一步研究表明,与对照相比,0.64 mmol/L FT处理可以抑制鲜切茄子多酚氧化酶（Polyphenol oxidase,PPO）和过氧化物酶（Polyphenol oxidase,POD）的活性,提高苯丙氨酸解氨酶（Phenylalanine ammonialyase,PAL）的活性和DPPH自由基清除率,降低总酚和醌的含量。因此,FT作为一种新型褐变抑制剂能较好地延缓鲜切茄子的褐变并延长其货架期。     

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。     

热处理条件筛选及其提高鲜切芋头贮藏品质的生理机制

为延长鲜切芋头贮藏期,本文研究热处理温度和时长对鲜切芋头贮藏品质的影响,并探究热处理控制鲜切芋头褐变的生理机理。结果表明,38、60和100 ℃的热处理均能降低鲜切芋头失重率、延缓硬度下降、抑制褐变,表明热处理能提高鲜切芋头的贮藏品质。60 ℃热处理效果最好,且60 ℃热处理1 min的保鲜效果要好于同温度下30 s和3 min的热处理效果。热处理降低了鲜切芋头总酚含量,抑制了苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)和多酚氧化酶(PPO)活性,延缓了鲜切芋头的酶促褐变。     

淮山褐变机理及其控制技术研究进展

淮山是一种营养价值极高的药食同源食品。褐变是淮山加工贮藏过程中影响其品质的主要问题之一,有效控制淮山褐变,保持其色泽和营养特性,提高其货架贮藏期,对保障淮山品质和提高消费者接受性具有重要意义。在已有研究的基础上,本文阐述了淮山酶促褐变与非酶褐变的相关机理,围绕酚类底物、酶及氧气等酶促褐变三要素阐述了淮山酶促褐变机理,并对淮山加工及贮藏中的美拉德反应和焦糖化非酶褐变机理进行了介绍;综述了不同褐变控制技术对淮山褐变的控制效果,分析现有问题,并对未来前景进行了展望,以期为淮山褐变控制技术的研究和应用发展提供参考。     

Cassava Starch Coating and Citric Acid to Preserve Quality Parameters of Fresh-Cut “Tommy Atkins” Mango

Abstract: Combination of citric acid dipping (5 g/L) and cassava starch coating (10 g/L), with and without glycerol (10 g/L), was studied to verify the effectiveness of these treatments to inhibit enzymatic browning, to reduce respiration rate, and to preserve quality parameters of “Tommy Atkins” fresh-cut mangoes during storage at 5 °C. Color characteristics (L* and C*), mechanical properties (stress at failure), weight loss, β-carotene content, sensory acceptance, and microbial growth of fruits were evaluated during 15 d. The respiration rate of fruit subjected to the treatments was also analyzed. Nontreated fresh-cut mango was used as a control sample. Cassava starch edible coatings and citric acid dipping promoted a decrease in respiration rate of mango slices, with values up to 41% lower than the control fruit. This treatment also promoted better preservation of texture and color characteristics of mangoes and delayed carotenoid formation and browning reactions during storage. Moreover, the treated fruit showed great sensory acceptance by consumers throughout the whole storage period. However, the use of glycerol in the coating formulation was not efficient in the maintenance of quality parameters of fresh-cut mangoes, promoting a higher weight loss of samples, impairing fruit texture characteristics, increasing carotenogenesis, and favoring microbial growth during storage. Practical Application: Consumer demand for tropical fresh-cut products is increasing rapidly in the world market. Fresh-cut mangoes are appreciated world-wide for its exotic flavor. However, its shelf life is limited by changes in color, texture, appearance, off-flavors and microbial growth. The edible coatings act as gas and water vapor barrier, extending the storage time of fresh-cut fruit and vegetables. Thus, cassava starch is an alternative to preserve minimally processed mangoes and the quality parameters of fresh fruit. The information of this work is useful for the fresh-cut produce industry to increase shelf life of fresh-cut mangoes, which can be considered an alternative to fast food and other ready-to-eat products, attending the demand for healthy and convenient foodstuffs.     

Identification of the miRNAs and their target genes involved in fresh-cut potato browning inhibition by nitrogen

Browning decreases the quality and shortens the shelf life of fresh-cut potato, causing enormous economic losses. This study indicated that nitrogen treatment could inhibit this browning process. However, whether microRNAs (miRNAs) are involved in inhibiting the fresh-cut potato browning by nitrogen remains unclear. Therefore, nine small RNA libraries were constructed and performed high-throughput sequencing using fresh-cut potatoes from control and nitrogen-treated for 1 h groups at 25 °C to identify the miRNAs and their target genes involved in fresh-cut potato browning inhibition by nitrogen. The results revealed that four common differentially expressed miRNAs (DEmiRNAs) were identified as associated with browning. The correlation analysis indicated that fresh-cut potato browning was closely related to the expression of DEmiRNAs and their potential target genes. The miR172d targeting APETALA2/ethylene response factor and phospholipase D, miR482e targeting ATPase GET3-like, and PC-3p-17015_391 targeting stachyose synthase are vital in the nitrogen inhibited fresh-cut potato browning by regulating the ethylene signalling pathway, membrane lipid metabolic process, ATPase activity, and carbohydrate metabolic process. This study provides new insights into fresh-cut potato browning inhibition and helps to improve the quality of fresh-cut potato using nitrogen.     

Effect of an Edible Nanomultilayer Coating by Electrostatic Self-Assembly on the Shelf Life of Fresh-Cut Mangoes

This work aims at evaluating the effect of an alginate-chitosan nanomultilayer coating, obtained by electrostatic layer-by-layer self-assembling, in the quality and shelf life of fresh-cut mangoes. Coated and uncoated fresh-cut mangoes were stored under refrigeration (8 °C) for 14 days. The changes in mass loss, titratable acidity, pH, ascorbic acid content, total soluble solids, malondialdehyde content, browning rate, and microbial count were evaluated during storage. At the end of the storage period, lower values of mass loss, pH, malondialdehyde content, browning rate, soluble solids, microorganisms’ proliferation, and higher titratable acidity were observed in the coated mangoes. The nanomultilayer coating did not improve the retention of vitamin C during storage of fresh-cut mangoes. Results suggest that chitosan-alginate nanomultilayer edible coating extends the shelf life of fresh-cut mangoes up to 8 days.