Comparative polyphenolic antioxidant profile and quality of traditional apple cultivars as affected by cold storage

‘Kathista’ and ‘Lortiko’ are regarded as traditional and highly appreciated apple cultivars in Cyprus, yet their postharvest behaviour and phytochemical content are largely unknown. Such fruits were examined for their qualitative traits, phenolic composition and antioxidant capacity after harvest or short, intermediate or extended cold storage and additional ripening at room temperature (RT), using ‘Gala’ as reference cultivar. Total phenolic content was dependent on cultivar and length of cold storage, while hydroxycinnamic acids were always at higher levels compared to total flavonols for all the examined cultivars. No clear trends regarding the influence of cold storage or RT maintenance on fruit antioxidant properties were evident. Overall, quality attributes and polyphenolic content of the traditional apple cultivars were comparable with ‘Gala’ at harvest; thus, they can be considered a good source of nutraceuticals as summer apple cultivars. However, extended cold storage deteriorates fruit behaviour and antioxidant capacity, particularly in ‘Lortiko’ fruit.     

Dynamic changes in wax and cutin compounds and the relationship with water loss in 'Red Fuji' and 'Golden Delicious' apples during shelf life

Knowledge of the dynamic composition changes of combined cuticular wax and cutin in apples during their shelf life is scarce. Therefore, this issue was addressed using GC-MS analyses of the respective epidermal components in 'Red Fuji' and 'Golden Delicious' apples at 5 days intervals during the shelf life of 25 days. Water loss from the apples was also assessed. The proportion of total n-alkanes decreased in cuticular wax, whereas total acids increased gradually, and cutin monomer content significantly changed during the first 5 days. The predominant wax compound, nonacosane (C₂₉), decreased by 40.13% and 26.22% in 'Red Fuji' and 'Golden Delicious' apples, respectively. The cutin monomers 10,16-dihydroxy hexadecanoic acid (10,16-diOH C_16:0) and 9,10,18-trihydroxyoctadecanoic acid (9,10,18-triOH C_18:0) were detected only at the beginning of shelf life in apples of both cultivars. Regression analysis indicated that the rate of water loss significantly correlated with eight components. Our results expand the understanding of the dynamics of both wax and cutin compounds in postharvest apples and help to target specific compounds to maintain the quality of apples throughout their shelf life.     

沙果多酚的提取及组成分析

采用水浴振荡辅助乙醇提取法提取沙果果干中的总多酚,对提取工艺进行优化并分析了沙果果干中的多酚种类。通过正交试验优化出沙果青果的最佳提取工艺:乙醇体积分数50%,料液比1∶25(g∶mL),水浴振荡时间50 min,水浴振荡温度30℃,此条件下多酚得率可达(7.875±0.008)mg/g;沙果熟果的最佳提取工艺:乙醇体积分数60%,料液比1∶25(g∶mL),水浴振荡时间30 min,水浴振荡温度40℃,此条件下多酚得率可达(10.259±0.020)mg/g。液相色谱分析表明:沙果青果多酚主要含有4种多酚,分别为绿原酸22.033%、原花青素B_(2)8.875%、表儿茶素5.95%和根皮苷1.259%,这4种多酚占总多酚的38.117%;沙果熟果除含有上述4种多酚(分别为41.0758%、5.6413%、8.3252%、0.4998%),还含有(+)-儿茶素(7.2444%),这5种多酚占总多酚的62.7865%,沙果中仍有大部分未知多酚未检出。沙果熟果多酚种类及含量高于青果,营养价值更丰富。     

离子液体修饰碳糊电极测定海红果中的槲皮素

用离子液体1-甲基-3-丁基咪唑六氟磷酸盐([bmim]PF6)作修饰剂制备了离子液体修饰碳糊电极(IL/CPE)。在0.2 mol/L B-R(p H 3.2±0.1)缓冲溶液中,采用循环伏安法研究了槲皮素在该修饰电极上的电化学行为,建立了测定槲皮素的新方法。研究表明,槲皮素在IL/CPE电极上的氧化、还原峰电位差比在裸碳糊电极(CPE)上的小,而峰电流却显著增加,说明IL/CPE对槲皮素有电催化作用;在循环伏安曲线上,槲皮素的峰电流与其浓度在0.1~50μmol/L呈良好的线性关系,其线性方程为ip(μA)=3.941 3+0.211 9 c(μmol/L),线性相关系数为0.999 4,检出限为3.0×10-8mol/L。该法用于测定海红果中的槲皮素取得了较好的结果。     

Effect of short‐term air storage after removal from controlled‐atmosphere storage on apple and fresh‐cut apple quality

BACKGROUND: One of the realities of apple distribution for long‐term stored fruit is that a controlled‐atmosphere (CA) storage room will be unsealed and fruit held in air storage and marketed over several weeks. This work was conducted to determine the effect of post‐CA air storage of whole fruit on potential shelf life for fresh‐cut apple slices. RESULTS: Fresh‐cut slices of ‘Spartan’ and ‘Delicious’ apples held in post‐CA air storage for 2 or 4 weeks showed the least changes in cut surface color as compared with those made from apples immediately on removal from CA. Shelf life was most improved by post‐CA air storage in the ‘Spartan’ apples, which were more advanced in maturity as compared with the ‘Delicious’ apples. Internal ethylene concentration, firmness, and respiration changed significantly with post‐CA air storage, suggesting a relationship between physiological status of the whole fruit and shelf life of slices made from that fruit. CONCLUSION: The results support the hypothesis that apples had suppressed physiological activity in CA storage and are susceptible to accelerated deterioration upon cutting. Holding fruit for 2 weeks in air storage allowed recovery of physiological activity, which resulted in greater resistance to deterioration in response to fresh‐cut processing. Copyright © 2010 Crown in the right of Canada. Published by JohnWiley & Sons, Ltd     

Short anaerobiosis period prior to cold storage alleviates bitter pit and superficial scald in Granny Smith apples

BACKGROUND: Californian Granny Smith apples are very susceptible to bitter pit (BP) and superficial scald symptoms that develop during cold storage. The main preventive means are diphenylamine dipping and/or gaseous application of the ethylene inhibitor 1‐methylcylclopropene (1‐MCP), which is effective against superficial scald but not against BP. This study investigated the efficacy of a non‐chemical alternative, low‐O₂ (LO2) stress, in preventing these two physiological disorders. RESULTS: Application of LO2 stress at 20 °C for 10 days prior to cold storage of Granny Smith apples reduced superficial scald and BP incidence and severity during 8 months at 0 °C. LO2 treatments induced volatile alcohols and reduced ethylene and 6‐methyl‐5‐hepten‐2‐one (MHO‐on) production, thereby reducing superficial scald development after 4 months at 0 °C. In addition, LO2‐treated fruits had higher pectin methyl esterase (MdPME) gene expression, similar to that of 1‐MCP‐treated fruits, associated with their higher firmness. Conversion of MHO‐on to 6‐methyl‐5‐hepten‐2‐ol (MHO‐ol) in LO2‐treated fruits may explain the lower scald development. CONCLUSION: The ratio between MHO‐on and MHO‐ol might serve as an index of superficial scald severity. Reduction of BP symptoms in LO2‐treated fruits could be due to accumulation of volatile alcohols in the peel tissue. Copyright © 2010 Society of Chemical Industry     

Influence of apple purée preparation and storage on polyphenol contents and antioxidant activity

The polyphenolic components of Idared and Shampion apple purées were determined by HPLC; chlorogenic acid was the most abundant acid (20.0 mg/100 g in microwaved Idared); other polyphenols identified in high concentrations included (−)-epicatechin, procyanidin B1 and B2; quercetin and cyanidin glycosides were found in minor concentrations. The Shampion purées had higher total phenolics (142 mg/100 g) and procyanidin B2 concentrations (17.3 mg/100 g) than the Idared ones, and polymeric procyanidins represented 41% of all polyphenols. Antioxidant capacities of the samples, determined by spectrophotometric methods and EPR spectroscopy, correlated well with the concentration of polyphenols. The antioxidant properties could be better represented by EPR than by UV–vis measurements. The latter require transparent (clear) samples whereas EPR can be a method of choice in the assessment of radical-scavenging activity of dense and cloudy apple purées. Our results support the putative high antioxidant value of apple purées and define their capacity in terms of the major constituents. Apple purées are a rich source of natural antioxidants, especially of chlorogenic acid and procyanidins.     

有机茶山海棠叶主要活性成分测定及模拟胃酸条件下清除亚硝酸盐的效果

以茶山海棠的春、夏、秋叶为研究对象,分别以自然冲泡法和磨碎浸提两种方式采用分光光度法测定多酚类、黄酮类和甜茶苷的质量分数。在模拟胃酸条件下,测定自然冲泡条件下不同固液比、不同反应时间对NO2的清除率的影响,并在此基础上分析各成分质量分数与清除亚硝酸盐(NO-2)的能力的相关性。结果表明,茶山海棠的多酚类质量分数在0.51%～1.55%,黄酮类在5.10%～12.20%,甜茶苷在2.34%～4.67%之间。自然冲泡条件下,3种茶汤都有较好的清除NO-2的能力,茶水比在1:50以下,对NO-2的清除作用随茶汤质量浓度的增加而增大。3种茶汤的NO-2清除率在固液比相同时存在显著性差异(P<0.05),其清除能力大小为:夏茶>春茶>秋茶。茶山海棠的春、夏、秋叶的NO-2清除率与黄酮类和甜茶苷的质量分数呈正相关性,与多酚类质量分数则无明显相关性。茶山海棠的清除NO-2反应较快,20min反应已基本完成;相同反应时间下,夏茶的清除率显著高于春茶和秋茶。