Using polysaccharide-based edible coatings to maintain quality of fresh-cut Fuji apples

The effect of alginate and gellan-based edible coatings on the shelf-life of fresh-cut Fuji apples packed in trays with a plastic film of a known permeability to oxygen (110 cm³ O₂ m⁻² bar⁻¹ day⁻¹) was investigated by measuring changes in headspace atmosphere, color, firmness and microbial growth during 23 days of storage at 4 °C. Concentration of O₂ and CO₂ in the package was measured and no significant differences between coated and uncoated fresh-cut apples were observed. Ethylene concentration in coated apples seemed to be delayed since it remained below 50 μl l⁻¹ throughout the whole refrigerated storage period, while production of this gas was detected in uncoated apples from the very initial days of storage. Coated apple wedges exhibited ethanol and acetaldehyde formation from the second week of storage indicating fermentative metabolism. Polymers were crosslinked with a calcium chloride solution, to which the antibrowning agent N-acetylcysteine was added, being incorporated into the coatings formulation and helping to maintain firmness and color of apple wedges during the entire storage time. The application of the edible coatings also retarded the microbiological deterioration of fresh-cut apples. Alginate and gellan edible coatings effectively prolonged the shelf-life of Fuji apple wedges by 2 weeks of storage compared with the control apple slices which showed a considerable cut surface browning and tissue softening from the very early days of storage, limiting their shelf-life to less than 4 days.     

短波紫外线控制鲜切苹果褐变与其活性氧代谢的相关性

为研究短波紫外线（ultraviolet-C,UV-C）处理对鲜切苹果褐变控制与活性氧（reactive oxygen species,ROS）代谢的相关性,分析贮藏过程中UV-C处理后鲜切苹果的ROS水平、抗氧化相关酶活力、抗氧化物质（VC）含量以及非酶抗氧化能力的变化。结果表明：UV-C处理能够有效抑制鲜切苹果的褐变,降低超氧阴离子自由基产生速率和H2O2、丙二醛（malondialdehyde,MDA）含量;同时,UV-C处理能够有效提高抗氧化相关酶（超氧化物歧化酶、过氧化氢酶、抗坏血酸过氧化酶和谷胱甘肽还原酶）活力以及VC含量,减缓鲜切苹果非酶抗氧化能力（1,1-二苯基-2-三硝基苯肼自由基、2,2’-联氮-双(3-乙基苯并噻唑-6-磺酸)阳离子自由基清除能力和还原能力）在贮藏过程中的下降;相关性分析与主成分分析结果显示,鲜切苹果褐变程度与ROS水平和MDA含量呈显著正相关（P＜0.05）,与抗氧化酶活力和非酶抗氧化能力呈显著（P＜0.05）或极显著（P＜0.01）负相关,且UV-C处理组鲜切苹果的ROS代谢能力高于对照组。因此,推测UV-C处理可能通过调节鲜切苹果的ROS代谢进而控制其贮藏过程中的褐变。     

氧化白藜芦醇对鲜切苹果及果汁褐变的影响

为研究氧化白藜芦醇(oxyresveratrol,OXY)对苹果褐变的抑制作用,采用不同浓度的OXY对鲜切苹果、苹果汁进行处理,探讨在不同储藏阶段切片色度和果汁褐变度变化情况及OXY对苹果汁内多酚氧化酶(polyphenol oxidase,PPO)和过氧化物酶(peroxidase,POD)活性的影响。结果表明:OXY可改善苹果切片的感官品质,显著延缓切片L*值的降低(P<0.05),抑制a*、b*、ΔE值的升高(P<0.05)。同时,OXY还能显著降低苹果汁褐变度(P<0.05),显著抑制苹果汁内PPO和POD活性(P<0.05)。综上,OXY能有效抑制鲜切苹果片及苹果汁褐变,其作用机制可能是通过抑制苹果内PPO和POD活性实现。     

Effect of Tapioca Starch/Decolorized Hsian-tsao Leaf Gum-Based Active Coatings on the Qualities of Fresh-Cut Apples

The effect of tapioca starch/decolorized hsian-tsao leaf gum (dHG)-based edible coatings with various food additives (including ascorbic acid, calcium chloride, and cinnamon oil) on the qualities and shelf life of fresh-cut “Fuji” apple pieces was investigated during the refrigerated storage. The initial respiration rate, headspace gas composition, color, texture, microbial quality, peroxidase activity, and sensory qualities were analyzed. The results were also compared to those for samples submerged in distilled water and the samples treated with 120-ppm chlorine solution widely used in the industry. It was found that ascorbic acid and cinnamon oil delayed the browning of fresh-cut apples effectively when being applied in the starch/dHG-based edible coating solutions. In combination with calcium chloride, starch/dHG coated fresh-cut apples retained satisfactory firmness. Incorporation of cinnamon oil in starch/dHG coatings significantly reduced the growth of microorganisms, respiration rate, CO₂, and ethylene production of fresh-cut apples, but these apple pieces received lower scores in overall preference during sensory evaluation. Among the starch/dHG-based active coatings studied, starch/dHG coatings with ascorbic acid and calcium chloride are suggested for fresh-cut apples, as they could enhance qualities in terms of color and firmness, and prolong the shelf life up to 5–7 days by providing reasonable microbial quality.     

Dual effectiveness of sodium chlorite for enzymatic browning inhibition and microbial inactivation on fresh-cut apples

The dual effectiveness of sodium chlorite for browning inhibition and microbial inactivation on fresh-cut apples was investigated and compared to other anti-browning and antimicrobial agents. Results indicate that sodium chlorite significantly (P < 0.001) inhibited the browning reaction of fresh-cut Red Delicious apples stored at 5 °C for 14 days. This treatment also significantly reduced polyphenol oxidase activities. Treatments with acidified sodium chlorite, calcium chloride, or calcium ascorbate exhibited strong inhibition on apple browning during the early storage, these treatment effects diminished after 7 days in storage. Combining calcium chloride with sodium chlorite further significantly (P < 0.001) improved the firmness of apple slices, and browning inhibition during storage. Additionally, treatments with acidified sodium chlorite, sodium chlorite, or the combination of sodium chlorite and calcium chloride significantly (P < 0.001) reduced Escherichia coli populations on fresh-cut apples by 3.0, 3.6, and 3.9 log cfu g⁻¹ over the water control. The dual effectiveness of sodium chlorite to inhibit enzymatic browning and inactivate E. coli may allow this compound to achieve a prominent role in improving the quality and safety of products in the fresh-cut apple and other food industries.     

鲜切苹果品质保持研究

文研究了不同褐变抑制剂对鲜切苹果PPO活性、褐变度、感官品质的影响。试验结果表明:单一的1.5%L-半胱氨酸、1.0%D-异VC钠、1.0%谷胱甘肽处理均能较好地抑制鲜切苹果褐变。采用0.10%D-异VC钠+0.12%谷胱甘肽+0.13%L-半胱氨酸,浸泡2min的复合处理,可使鲜切苹果的PPO活性、褐变度、感官品质在14d内保持较优水平。     

鲜切苹果抗褐变研究

研究了不同褐变抑制剂对鲜切苹果PPO(多酚氧化酶)活性、褐变度、感官品质的影响。试验结果表明单一的1.5%L-半胱氨酸、1.0%D-异VC钠、1.0?TA-2Na处理均能较好地抑制鲜切苹果褐变。采用0.10%D-异VC钠 0.12?TA-2Na 0.13%L-半胱氨酸,浸泡2min的复合处理,可使鲜切苹果的PPO活性、褐变度、感官品质在14d内保持较优水平。     

高压氩气和氮气处理对鲜切苹果冷藏的保鲜效果

将鲜切苹果用高压(25MPa)氩气和氮气处理1h,以未处理和高压(25MPa)空气处理的鲜切苹果为对照,研究了在14d的冷藏期间高压氩气和氮气处理对鲜切苹果生理及贮藏品质的影响。研究结果表明,高压氩气和氮气处理降低了冷藏期间鲜切苹果的呼吸强度和乙烯产生量,减少了褐变反应的发生,很好的保持了鲜切苹果的色泽和总酚,且不影响可滴定酸和可溶性固形物含量。同时,还抑制了鲜切苹果中微生物的繁殖生长,在14d冷藏中,将嗜冷好氧菌生长量控制在6.0lg(CFU/g)以下,霉菌和酵母菌生长量控制在4.0lg(CFU/g)以下。高压氩气处理的保鲜效果好于高压氮气处理。但高压氩气和氮气处理会对鲜切苹果的组织硬度产生一定负面影响,降低鲜切苹果的硬度。     

半胱氨酸控制鲜切苹果褐变的生理机制

为研究半胱氨酸对鲜切苹果褐变控制的生理机制,以鲜切苹果为研究对象,采用0.5 g/L的半胱氨酸溶液处 理1 min,分析贮藏过程中鲜切苹果褐变指数（browning index,BI）、多酚氧化酶（polyphenol oxidase,PPO）和 抗氧化酶活力、抗氧化物质和丙二醛（malondialdehyde,MDA）质量摩尔浓度及抗氧化能力的变化。结果表明, 与蒸馏水处理相比,半胱氨酸处理能够显著抑制鲜切苹果的褐变,在贮藏初期半胱氨酸处理降低了鲜切苹果的PPO 活力,同时在贮藏过程中不同程度提高了鲜切苹果的抗氧化酶活力以及抗氧化能力,减缓了抗氧化物质在贮藏过程 中的损失,并且抑制了MDA的积累。相关性分析显示,鲜切苹果的BI值与抗坏血酸含量、过氧化氢酶活力以及抗 氧化能力呈极显著负相关（P＜0.01）,与MDA质量摩尔浓度呈极显著正相关（P＜0.01）。因此,半胱氨酸可能是 一方面通过抑制鲜切苹果的PPO活力,另一方面通过提高其抗氧化能力,延缓贮藏过程中的组织褐变。     

Phenolic profiling reveals the metabolite basis of flesh colour and fresh-cut browning in apple fruit

Flesh colour, which is affected by cultivars and browning, can largely impact consumer acceptance in fresh-cut apples. The study profiled phenolic metabolites from apple flesh of twenty-three cultivars by widely targeted metabolomics. Comparison among white- and yellow-fleshed cultivars showed fifteen phenolics, mainly quercetin 3-O-glucoside, hyperoside, hesperetin 5-O-glucoside and cymaroside, in white-fleshed apples were significantly higher than those in yellow-fleshed apples. It may indicate a metabolite basis of yellow and white flesh colour, and better potential nutrition in white-fleshed apples. In addition, ten phenolic metabolites including five cyanidin glycosides showed significant differences between the highest and the lowest browning groups, indicating them may be crucial in browning of fresh-cut apple. This work elucidates the differences of phenolic profiles among apple cultivars with different flesh colour and provides useful data to evaluate the suitability of apple for fresh-cut processing.     

紫外线照射与柠檬酸处理对鲜切苹果的保鲜作用

目的研究柠檬酸、紫外线照射、柠檬酸和紫外线照射联合处理对鲜切苹果生理生化的影响。方法以富士苹果为实验材料,分成4组,分别是0.5%柠檬酸(CA)溶液中浸泡5 min、紫外照射(UV)5 min/面、0.5%柠檬酸溶液中浸泡5 min+紫外照射(CA+UV)5 min/面、不处理的对照组(KB)。分别于0、1、3、5、7、10、13、15 d测定鲜切苹果的色差、多酚氧化酶(PPO)、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)活性。结果富士苹果经过切分后,褐变严重。PPO、POD活性升高,PAL活性变化曲折,总体呈上升趋势。柠檬酸、紫外、柠檬酸和紫外联合处理的3三种处理方式都可以抑制鲜切苹果的褐变,降低PPO、POD、PAL的活性。在4种处理方法比较中,柠檬酸和紫外联合处理的效果比较好。结论柠檬酸和紫外联合处理是鲜切苹果的理想的保鲜方法。     

Respiration and Storage Quality of Fresh-Cut Apple Slices Immersed in Sugar Syrup and Orange Juice

Storing fresh-cut apple slices in suitable fruit juice or sugar syrup is a general practice. However, application of this approach is mainly based on empirical knowledge, while systematic and comprehensive analyses of the relevant effects of this storage technique on keeping quality-related physiological properties of fresh-cut products is still missing. Hence, the aim of this study was to evaluate the impacts of complete immersion of fresh-cut apples in sugar syrup and fruit juice solution on respiratory behaviour and other relevant quality attributes (colour, tissue strength, and soluble solid and acidity). Sugar syrup and pure orange juice showed a high potential to store and protect fresh-cut apples. Results showed that only pure orange juice positively affected the produce quality by preventing browning effects. In addition, sugar syrup of 13.4–20% most effectively prevented browning of apple slices and guaranteed high product quality retention during storage. The application of different liquid media provides a practical means to prevent browning and maintain product quality.     

Effect of Solid Content and Lipid Content of Whey Protein Isolate-Beeswax Edible Coatings on Color Change of Fresh-cut Apples

ABSTRACT: Edible coatings from whey protein isolate (WPI)-beeswax (BW) were made with various total solid (8%, 12%, 16%, 20%) and BW content (0%, 20%, 40%, 60%, dry bases). Apple pieces were coated with the emulsion coatings; weight loss and color (CIE L*, a*, b* , and browning index [BI]) were measured during storage. Results show that coated apples had higher L* and presented lower BI than uncoated apples, indicating that whey proteins exert an antibrowning effect. The BI decreased as the solid content of the coating emulsions increased. Increasing BW content decreased enzymatic browning. Coating application did not reduce weight loss in fresh-cut apples, probably due to the product's high relative humidity.     

Effectiveness of edible coatings to inhibit browning and inactivate foodborne pathogens on fresh-cut apples

Multiple formulations of edible coating solutions were developed and evaluated for their ability to maintain the quality and minimize populations of foodborne bacteria on fresh-cut apples. Fresh-cut apples were artificially inoculated with Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes, and dip-treated with coating solutions. Changes in populations of pathogens and molds and yeasts (M&Y) were evaluated after solution treatments and during storage at 4°C for 35 days. Changes in color, texture firmness, and weight loss during storage were also determined. Among the formulations, the solution containing 1% of three organic acids (acetic, lactic, and levulinic acids), 2% N-acetyl-l-cysteine or L-cysteine with 0.5% chitosan demonstrated the best effectiveness for the simultaneous reduction of pathogenic and spoilage microorganisms, control of browning, and maintenance of the quality of fresh-cut apples. The treated apple slices had nondetectable pathogens and M&Y (<1 log CFU) and the least quality changes for 35-day storage. The developed solutions can be used at processing plants, retail stores, or homes to protect fresh-cut apples or other fresh-cut fruits and vegetables from microbiological and quality deterioration.     

真空浸渍辅助L-半胱氨酸处理对贮藏期鲜切马铃薯的护色作用

为研究L-半胱氨酸(L-cysteine,L-cys)对鲜切马铃薯的抗褐变机制,以鲜切马铃薯为研究对象,采用真空浸渍技术辅助0.7 g/L的L-cys溶液处理鲜切马铃薯,分析贮藏期鲜切马铃薯褐变指数(browning index,BI)、多酚氧化酶活性(polyphenol oxidase,PPO)、过氧化物酶活性(peroxidase,POD)、苯丙氨酸解氨酶活性(phenylalanineammonialyase,PAL)、总酚含量及抗氧化活性的变化。结果表明,在贮藏期,试验组鲜切马铃薯BI值、PPO活性、POD活性、PAL活性均显著低于对照组(p<0.05)。试验组总酚含量在贮藏0~6 d,显著低于对照组(p<0.05),但贮藏后期则显著上升(p<0.05)。另外,两组鲜切马铃薯抗氧化活性在贮藏期,均呈先上升后下降趋势。因此,结果表明,L-cys处理可以抑制鲜切马铃薯酶活性,从而延缓鲜切马铃薯在贮藏期间的褐变。     

短波紫外线处理对贮藏期鲜切马铃薯的护色作用

为研究短波紫外线(ultraviolet-C,UV-C)对贮藏期鲜切马铃薯的护色作用,在输出功率为15 W条件下对鲜切马铃薯辐照处理6 min.检测0～12 d贮藏期内褐变指数(browning index,BI)、多酚氧化酶(polyphenol oxidase,PPO)活性、过氧化物酶(peroxidase,POD...     

Apple Wraps: A Novel Method to Improve the Quality and Extend the Shelf Life of Fresh-cut Apples

A novel method was developed to extend the shelf life and improve the quality of fresh-cut produce. Edible coatings and films were made from apple puree with various concentrations of fatty acids, fatty alcohols, beeswax, and vegetable oil. Apple pieces were coated with solutions or wrapped in preformed films. Changes in moisture content and color were measured during storage. Increasing concentrations of lipids significantly improved the moisture barrier properties of films. Water vapor permeability varied from 69 to 325 g mm/kPa d m². Apple-based wraps significantly reduced moisture loss and browning in fresh-cut apples. Color was preserved for 12 d at 5 °C. Wraps were significantly more effective than coatings.     

Effects of plasma-activated water on microbial growth and storage quality of fresh-cut apple

Fresh-cut ‘Fuji’ apples were immersed for 5 min in plasma-activated water (PAW) generated, by plasma generated with sinusoidal voltages at 7.0 kHz with amplitudes of 6 kV, 8 kV, and 10 kV, designated PAW-6, PAW-8, and PAW-10, respectively. The control group was soaked in distilled water for 5 min instead of PAW. The results indicated that the growth of bacteria, molds, and yeasts was inhibited by PAW treatments during storage at 4 ± 1 °C, especially the microbial inactivation with PAW-8, which was the most efficient. PAW-8 reduced the microbial counts by 1.05 log₁₀CFU g⁻¹, 0.64 log₁₀CFU g⁻¹, 1.04 log₁₀CFU g⁻¹ and 0.86 log₁₀CFU g⁻¹ for aerobic bacteria (aerobic plate counts), molds, yeasts and coliforms on day 12, respectively. In addition, the bacterial counts of fresh-cut apples treated with PAW were <5 log₁₀CFU g⁻¹, which did not exceed to the existing China Shanghai local standard (DB 31/2012–2013) during 12 days of storage. PAW treatments reduced superficial browning of fresh-cut apples without affecting their firmness and titratable acidity. In addition, no significant change was observed in antioxidant content and radical scavenging activity between the PAW-treated and control groups. It is suggested that PAW is a promising method for preservation of fresh-cut fruits and vegetables, which is usually beneficial to the quality maintenance of fresh-cut fruits and vegetables during storage.     

Novel Browning Inhibitor Formulation for Fresh-cut Apples

ABSTRACT: Development of a browning inhibitor for fresh-cut apples that would not support human pathogen survival was investigated. Granny Smith and Fuji wedges were treated with acidic or neutral browning inhibitors with and without addition of sodium hexametaphosphate. Wedges in modified atmosphere packaging pouches were observed for browning during storage at 4 °C and 10 °C. A pH 2.9 dip containing ascorbic acid, citric acid, and sodium hexametaphosphate suppressed browning for at least 3 wk at 4 °C, whereas formulations without hexametaphosphate failed within 1 wk. These results demonstrate that browning in fresh-cut apples can be controlled with a formulation unlikely to support human pathogen survival or growth.     

高压二氧化碳处理对鲜切荸荠褐变的影响

为了延长鲜切荸荠的贮藏周期,本文研究冷藏条件下高压二氧化碳（HPCD）处理对鲜切荸荠褐变的影响。鲜切荸荠经高压二氧化碳（1、2、4 MPa,31℃,5 min）处理后,放在4 ℃条件下冷藏8 d,测定其在贮藏期间的色泽、硬度、多酚氧化酶活性、过氧化物酶活性、苯丙氨酸解氨酶活性及多酚类物质的变化情况。结果表明,经2 MPa和4 MPa处理均可有效抑制鲜切荸荠的褐变,而2 MPa处理可更大程度地减缓硬度的降低。与对照组相比,不同压力处理均能激活多酚氧化酶、过氧化物酶,抑制苯丙氨酸解氨酶活性,延缓多酚类物质的积累。其中,经2 MPa处理组效果最佳,贮藏至第4 d,苯丙氨酸解氨酶活性和多酚含量分别较对照组低59.1%和46.1%。研究结果可为HPCD技术在抑制鲜切果蔬褐变方面的应用提供参考。