柿树乙醇脱氢酶活性与可溶性单宁含量的关系

研究了4种不同脱涩类型柿(Diospyros kaki Thunb)果实和叶片中的可溶性单宁含量、乙醇脱氢酶（alcohol dehydrogenase, ADH）活性和ADH最适反应温度,以了解ADH在脱涩过程中的作用。结果表明：不完全甜柿和完全甜柿果实发育前期,可溶性单宁含量逐渐降低,ADH活性逐渐增高,到果实基本完成脱涩后,ADH活性又开始降低,在不完全甜柿中变化较大;涩柿和不完全涩柿在果实近熟期,可溶性单宁含量有所下降,但不能完成脱涩,且ADH活性较低。叶片发育过程中,可溶性单宁含量的变化与ADH没有相关性。乙醇脱氢酶的最适反应温度在25℃左右。ADH与柿果实脱涩有一定关系。     

新鲜柿脱涩技术

1脱涩的原理柿果实内含有一种特殊的细胞,它的原生质里含有很多单宁物质,被称为单宁细胞。涩柿果实中的单宁,绝大多数以可溶性状态存在于单宁细胞内。当人们咬破果实后,部分单宁流出来,被唾液溶解,使人感到有强烈的涩味。甜柿果实中的单宁,绝大多数以不溶性状态存在,当人们咬破果实后,单宁不为唾液所溶解,所以不会感到有涩味。脱涩,就是将可溶性单宁变为不溶性单宁,并不是将单宁除去或减少,这种变化在单宁细胞内较容易进行。2脱涩的作用柿脱涩的作用大致分两种:直接作用和间接作用。2.1直接作用用酒精、石灰水、食盐等化学物质,渗入单宁细胞…     

柿子如何脱涩贮存保鲜

正如何将柿果内可溶性单宁变为不可溶性,使人感觉不到涩味,对涩柿品种脱涩的主要方法有以下几种。温水法即用草帘围护大缸保温,将柿果浸入40℃左右的温水中,保持水温,经10~24h即可脱涩。此法可使柿果保持原有硬度及脆度,且果色鲜亮。石灰水法将采收后的柿子浸泡于用生石灰刚配好的4%的石灰水内,约2~3d即可脱涩。此法脱涩的柿果鲜脆可口。鲜果混存法100kg柿果与3~5kg苹果、梨等分层相     

采收期对‘富平尖柿’生理特性的影响

【目的】探索采收期对‘富平尖柿’的生理代谢影响,寻找其最佳采收期,提高果品商品品质。【方法】以‘富平尖柿’为试材,采用对比试验法,于10月13日开始,每间隔5日,采收一次柿果,直至11月3日,共采收5个批次,调查了不同采收期采收的柿果的色泽、单果质量、硬度、水分、可溶性固形物含量、呼吸强度、总单宁、可溶性单宁、聚合单宁、原果胶、可溶性果胶、乙醇、乙醛含量及果胶酶、乙醇脱氢酶、多酚氧化酶(PPO)的活性变化,分析了不同采收期对‘富平尖柿’的理化品质指标和生理特性影响。【结果】在试验采收期内,随着采收期的延迟‘,富平尖柿’的绿色变淡,色泽变得更黄,单果质量增加,硬度降低,水分含量增大,可溶性固形物含量增高,呼吸强度降低,可溶性单宁含量减少,聚合单宁含量增加,原果胶含量降低,可溶性果胶含量增多,果胶酶活性增强,乙醇、乙醛含量及乙醇脱氢酶、多酚氧化酶活性随采收期延迟先增高后降低‘,富平尖柿’在霜降后5～10 d采收,各种理化品质较好,柿子能保持良好的硬度、色泽和内在品质。【结论】富平尖柿最适采收期位于霜降后5～10 d,此时采收的‘富平尖柿’色泽好,可溶性固形物含量高,硬度适中,果品商品性指标较好,利于后期的运输保藏和加工操作。     

柿果脱涩新技术试验

柿树品种资源丰富,在全国分布很广,产量仅次于苹果、梨、柑桔。由于涩柿含可溶性单宁(主要成分是三羟基苯和没食子酸也称柿子素 Diospynin)味涩。涩柿充分成熟之后,不能在树上脱涩,采后须经后熟或人工脱涩方可食用。脱涩作用是在适当温度下通过某些化学物质使酶活化刺激果实成熟,或由无氧呼吸的中间产物与单宁物质结合使之凝固成为不溶性的树脂状物质(络合物),食用时感觉不出涩味。传统的脱涩方法很多,如农家自古以来有使用温水脱涩法、碱法脱涩、草法(辣蓼草)脱涩、土窖烟烘法、盐矾法等。随着科技迅速发展,又采取了物理化学方法脱涩,     

浙江省本土柿资源果实营养指标分类因子筛选研究

对浙江省本土柿果实营养品质性状进行分类因子的筛选研究，为选育本地优良柿资源提供科学方法。以237份浙江省本土柿资源为样本，对可溶性固形物、粗纤维、类胡萝卜素、矿质元素等13个营养指标进行了变异分析、相关性分析、主成分分析、聚类分析，最终进行分类因子筛选。最终筛选出含水量、可溶性固形物、可溶性糖、淀粉、类胡萝卜素、单宁、粗纤维等7个指标作为浙江省本土柿资源果实营养品质性状的分类评价因子。7个分类评价因子能够反映柿果实汁液、果实甜度、果肉质地、果肉颜色、脱涩程度、化渣性等果实品质，对筛选优良柿品种具有较大意义。     

采收期对富平尖柿贮藏过程中生理生化特性的影响

【目的】探究采收期对富平尖柿贮藏特性的影响,提高贮藏效果,为富平尖柿的柿饼生产应用提供理论参考。【方法】采用对比试验法,测定了不同采收期富平尖柿果实在(-2±0.5)℃、相对湿度(85±5)%的条件下贮藏过程中的失重率、硬度、水分含量、可溶性固形物含量、呼吸强度、单宁含量、果胶含量、乙醇含量、乙醛含量,以及果胶酶、乙醇脱氢酶、多酚氧化酶活性的变化规律。【结果】不同采收期柿果呼吸强度差异较大,随着贮藏时间的延长,呼吸强度明显降低,最后趋于一致;随着采收期延迟和贮藏时间延长,柿果失重率、相对含水量以及可溶性果胶、聚合单宁、乙醇及乙醛含量增加,硬度以及可溶性固形物、原果胶、可溶性单宁含量降低,果胶酶、乙醇脱氢酶及多酚氧化酶活性下降。【结论】不同采收期柿果的特性差异较大,对贮藏过程中的生理生化特性具有较大影响,在霜降后5～10 d采收富平尖柿,并于(-2±0.5)℃、相对湿度(85±5)%的冷库中贮藏30 d,富平尖柿能保持一定硬度,有较好的生理生化指标,完全满足柿饼加工的要求。     

不同种质核桃中酚类物质及其抗氧化性研究

以核桃为研究材料,通过采用DPPH自由基清除力、还原力、单宁、总酚和酚类物质为抗氧化指标,对8种不同地域和种质的核桃的抗氧化能力进行比较。结果表明,陕西纸皮核桃的DPPH自由基清除率最强,河北薄皮核桃最弱;陕西纸皮核桃的还原力最强,山西薄皮核桃最弱;总酚和单宁含量中,河北薄皮核桃最高,新疆纸皮核桃最低;酚类物质检测中芦丁含量最高。相关性分析结果表明,酚类物质含量和核桃的DPPH自由基清除能力、还原力和单宁含量均有较高的相关性,说明核桃中抗氧化活性物质主要为酚类化合物。此外,河北薄皮核桃和新疆薄皮核桃具有较强的抗氧化能力,益于人体健康,可为其品种选育和适用性的研究提供参考。     

‘乾县火柿’常温保鲜贮藏研究

‘柿鲜Ⅰ’药剂处理刚转黄的‘乾县火柿’,不但保持了硬度,而且保持了可溶性固形物和维生素 C 含量.常温下贮藏三个月后,“柿鲜Ⅰ_4一Ⅰ_7”处理的果实硬度都在5.6kg/cm~2以上.可溶性固形物在15%以上.好果率大于86.2%.“柿鲜Ⅰ_7”处理的好果率高达99.2%.常规脱涩后硬柿风味不变.多聚半乳糖醛酸酶(PG)和纤维素酶对柿果的软化有直接作用.“柿鲜Ⅰ”的保鲜机理主要是抑制果实内部乙烯产生和减小呼吸强度.抑制 PG 和纤维素酶的活性,从而减缓不溶性果胶和纤维素的水解.     

不同烹饪方式对毛葱抗氧化活性的影响

以毛葱为研究对象,研究水煮、蒸制和油炸等不同烹饪方式处理对其总酚含量和抗氧化活性的变化。利用福林酚法测定总酚含量,采用DPPH自由基清除能力、ABTS自由基清除能力和还原能力3个指标评价抗氧化活性。结果表明:水煮、蒸制、油炸3种烹饪加工后毛葱的总酚含量均降低,烹饪处理降低了毛葱对自由基的清除能力,却提高了其还原能力。不同烹饪处理后总酚含量和抗氧化活性为:蒸制>水煮>油炸,且烹饪时间越长总酚含量越少,抗氧化能力越弱。     

部分中国原产甜柿种质果实脱涩类型的鉴定

 以部分中国原产甜柿为试材, 通过对可溶性单宁含量测定和单宁细胞切片观察发现, 在果实接近成熟时, ‘罗田甜柿’、‘宝盖甜柿’、‘秋焰甜柿’ (鄂柿1号) 果肉中单宁细胞较小, 所占比例较低,可溶性单宁含量低于0.2%。因此确认供试中国甜柿种质属于完全甜柿。     

1-MCP处理对不同采收期鸭梨货架期保鲜效果的影响

利用1-MCP(1-methylcyclopropene)对不同采收期鸭梨进行采后处理,冷藏6个月后观察室温条件下的货架保鲜效果.结果表明:1-MCP处理可有效抑制不同采收期鸭梨果实乙烯的释放,推迟呼吸高峰,保持果实硬度及感官品质,减缓可溶性固形物含量、果皮电导率及果肉中丙二醛含量的上升,延缓了果实的后熟衰老进程.     

Use of refractometer to determine soluble solids of astringent fruits of Japanese persimmon (Diospyros kaki L.)

A method was developed to determine soluble solids refractometrically in astringent Japanese persimmon fruits with a high soluble tannin content. Adding 5% PEG # 6000 to the fruit juice in equal amount followed by centrifugation or filtration removed interfering tannins effectively from the mixture by forming precipitates. The refractometer readings were taken with the resultant solution and 2.5% PEG # 6000 and then the refractometer sugar value of the original juice was calculated by multiplying by two the difference of the two readings. The calculated value approximated closely to the total sugar content of juice.     

甜柿新品种—川甜柿2号的选育

川甜柿2号甜柿是从日本引进品种前川次郎优选单株培育出的早熟大果型甜柿优良品种。果实9月下旬成熟,扁圆形,果面橙红色,平均单果质量227g,均匀整齐;果肉黄红色,褐斑细小而少或无,肉质甜脆、爽口,果实成熟时可溶性固形物含量16%～18%,维生素C含量超过120mg/100g,可溶性单宁含量为0.032%,在树上完全自然脱涩。保脆期长,较耐贮运。与君迁子嫁接亲和力强,树体生长旺盛,早果、丰产,适应性广,抗病虫能力较强,较耐瘠薄及粗放管理,适合山地和丘陵地区种植。     

Physico-chemical changes during growth of persimmon fruits in the East Mediterranean climate region

Physico-chemical changes were monitored during growth of pollination variant non-astringent ‘Harbiye’ persimmon fruits (Diospyros kaki L.) grown at low or high altitude of the East Mediterranean Region of Turkey for two growing seasons (2001–2002 and 2002–2003). Fruit growth in diameter followed a typical double sigmoid curve, consisting of two rapid growth stages, stage I and stage III, separated by a period of slow growth (stage II) at both altitudes. The durations of stages I, II and III were 105–119, 21–35 and 21–42 days, respectively, at low and high altitude. ‘Harbiye’ persimmons showed significant decreases in soluble tannin concentration and total carotenoid content during stage I. At the end of stage I, ‘Harbiye’ persimmons became non-astringent. Stage II was characterized with slow growth, the beginning of acid degradation and a significant increase in total sugars, especially in the sucrose component. At end of stage II, the fruit began to turn yellow-orange, indicating the occurrence of colour break. The greatest increase in total soluble solids (TSS) content occurred in the final month before harvest during stage III when pronounced changes in skin colour and softening of fruits were observed. The 175 and 168 days after full bloom (DAFB) at low and high altitudes, respectively, are appropriate timing for harvest of the ‘Harbiye’ persimmon fruits in the East Mediterranean region. At these stages, ‘Harbiye’ persimmon fruits reached the best quality for consumers.     

Influence of Melatonin Treatments on Fruit Quality and Storage Life of Sweet Cherry cv. ‘Sweetheart’

The study was carried out to determine the effect of melatonin on quality and postharvest life of sweet cherries (Prunus avium L.) cv. ‘Sweetheart’ during storage. The fruits were dipped at different concentrations of melatonin (0, 250, 500 and 1000?µmol l^?1 for 10?min) and distilled water as control. The changes of sweet cherries were assessed at 7?day intervals by evaluating the following quality parameters: firmness, soluble solids content, titratable acidity, respiration rate, color values (L* and chroma), ascorbic acid content, total anthocyanin content, total phenolic content, and antioxidant activity. The results showed that increasing the dose to 1000?µmol l^?1 melatonin had a remarkable effect on maintaining the quality of sweet cherry. 1000?µmol l^?1 and 500?µmol l^?1 melatonin treatments significantly inhibited the decrease in firmness, ascorbic acid, total phenols, total anthocyanin, antioxidant content and reduced color changes and respiration rate. However, the total soluble solids content and titratable acidity of the fruit were not influenced by melatonin applications. These findings indicate that melatonin treatment may be effective in maintaining quality and bioactive compounds of sweet cherry fruit.

     

The role of Pre-harvest Aminoethoxyvinylglycine (AVG) Treatments on Total Phenolics,Antioxidant Capacity and Fruit Quality Attributes of Sweet Cherry Cultivars

The present study was conducted to investigate the effects of pre-harvest aminoethoxyvinylglycine (AVG) treatments on fruit quality parameters and bioactive compounds of sweet cherry fruits (Prunus avium L. cvs. ’0900 Ziraat’, ‘Regina’ and ’Sweetheart’). Whole trees were sprayed once with an aqueous solution containing AVG (0, 100 and 200?mg L^?1) three weeks before the anticipated commercial harvest. Measurements were performed a week before anticipated harvest date, at anticipated harvest date and a week after anticipated harvest date. AVG treatments significantly maintained flesh firmness of all three sweet cherry cultivars. Harvest was delayed at least for a week through the keeping of flesh firmness with AVG treatments. The treatments slowed down the red skin color development in all three cultivars. The measurements performed over fruits collected at different ripening stages revealed that AVG resulted in decreased total phenolics and total anthocyanin and ultimately decreased antioxidant capacity in sweet cherry fruits. AVG treatments also decreased soluble solids content and increased titratable acidity of the fruits. This study revealed that pre-harvest AVG treatments were more effective in delaying sweet cherry fruit softening. The main advantage is to maintain the firmness of late-harvested fruit by retaining fruit quality attributes of sweet cherry fruit.     

外源甜菜碱处理对冷藏桃果实冷害和品质的影#br# 响

 研究了外源甜菜碱（GB）处理对‘雨花2 号’水蜜桃冷害和品质的影响。结果表明,不同 浓度（5、10、20 mmol · L-1）外源GB 处理可有效抑制桃果肉褐变,减轻冷害症状,其中10 mmol · L-1 GB 处理效果最明显。外源GB 处理可减少桃果实冷藏期间细胞膜渗透性增加和丙二醛的积累,抑制多酚氧化 酶（PPO）、过氧化物酶（POD）活性。10 mmol · L-1 GB 处理还能够保持桃果实较高的果肉出汁率、可溶 性固形物、总酚和维生素C 含量,并且提高DPPH 自由基清除率和总还原力。这说明外源GB 处理能减 轻桃果实冷藏期间冷害发生,保持果实营养品质,具有较好的应用前景。     

Soil and rootstock influence on fruit quality of plums (Prunus domestica L.)

Soil and rootstock can particularly affect the ‘Rainha Claudia Verde’ (Prunus domestica) fruit quality, mainly its firmness characteristics. To investigate the variation in fruit quality, plums were harvested at commercial maturity from trees grafted on Marianna GF8-1 (Prunus cerasifera × munsoniana) and Marianna GF10-2 (P. cerasifera × munsoniana) rootstocks on two different soils: Haplic Luvisol and Vertic Luvisol. After harvest fruits were stored at 2 °C for 3 weeks. At the harvest day a small group of fruits were analysed without cold storage. During storage fruits were tested for firmness, soluble solids content, titratable acidity and fruit mineral content. Tree vigour was evaluated from trunk cross-sectional areas values.The GF8-1 rootstock promoted the highest vegetative development, comparing to GF10-2. This rootstock promoted the largest fruits size and the higher calcium fruit level. Positive correlations were found between higher concentrations of calcium in the pulp fruits and firmness. Fruits from two different rootstocks showed the same firmness at harvest but during cold storage, fruits from GF10-2 rootstock exhibited the highest firmness pulp values. There weren’t significant differences in fruit nitrogen and potassium levels for any studied factor.At harvest solids soluble content and solids soluble content/titratable acidity ratio weren’t affected by soil type or rootstock. As expected, solids soluble content during cold storage increased and solids soluble content/titratable acidity had a slight increase.GF10-2 revealed to be a good option as a ‘Rainha Claudia Verde’ rootstock for plums growers due to its intermediate-vigour. Also GF10-2 fruits presented better quality during storage comparing with GF8-1.