Effect of maturation and cold storage on the organic acid composition of myrtle fruits

BACKGROUND: The effect of maturation and senescence on the chemical composition of two myrtle cultivars was studied in mature, overripe and cold‐stored fruits in order to find the most appropriate harvesting period and best storage technology for industrial purposes. RESULTS: After cold storage at 10 °C for 15 days, berry weight loss ranged from 12.5 to 18.4%, with the highest losses in less mature fruits. Titratable acidity decreased during maturation and cold storage in both cultivars. Reducing and total sugars increased during maturation. Anthocyanin concentration increased during maturation but decreased in overripe berries. The major organic acids in myrtle fruits were quinic, malic and gluconic acids. In fresh and cold‐stored fruits, malic acid rose to 3 g kg^?1 and decreased thereafter. Quinic acid peaked at 90 or 120 days after bloom and decreased thereafter to reach low concentrations in mature fruits. CONCLUSION: Cold storage for 15 days at 10 °C does not affect myrtle fruit quality for liqueur production. Anthocyanin concentration is the best indicator of harvest time for industrial purposes. Gluconic acid concentration is high in mature, overripe and cold‐stored berries. This parameter can be used as a marker of the onset of fruit senescence. Copyright © 2012 Society of Chemical Industry     

FACTORS AFFECTING CHLOROGENIC, QUINIC AND CAFFEIC ACID LEVELS IN SUNFLOWER KERNELS

SUMMARY— Location of the seed on the sunflower head and storage temperatures were related to chlorogenic, caffeic, and quinic acid levels. Kernels of freshly harvested sunflower seeds located near the center of the head were higher in chlorogenic acid than seeds located near the margin. The opposite was obtained for the caffeic acid content, and quinic acid did not exhibit a positional effect. Chlorogenic acid content decreased during storage at 5°C, 15°C, and 40°C for 120 days; seeds attained the same levels of chlorogenic acid but varied slightly among treatments. Relatively small changes occurred in the caffeic and quinic acids content during storage.     

Sugars and organic acids in Japanese plums (Prunus salicinaLindell) as influenced by maturation, harvest date, storage temperature and period

The effects of fruit maturation, harvest date, storage temperature, storage period and shelf life, on the concentrations of individual sugars and organic acids in Japanese plums were investigated. During fruit maturation in 'Amber Jewel' plums, sucrose concentration increased significantly from 101 days after full bloom (DAFB) to 1 week after commercial maturity (136 DAFB) with a non-significant change in the concentration of total organic acids and malic acid, the major organic acid. The changes in concentrations of sugars and organic acids during cold storage of 'Amber Jewel' plums harvested on 129 and 136 DAFB appeared to be independent of harvest date. Storage of 'Amber Jewel' plums at 5 °C accelerated the loss of sucrose and increased the concentrations of fructose and glucose from the 4^th week of storage compared with those stored at 0 °C. 'Blackamber' plums did not undergo any significant increase in the total and individual sugars during 5 weeks storage and subsequent shelf-life of 8 days at 20 °C. Malic acid concentrations declined during storage from 3 weeks onwards with a further substantial loss during ripening at 20 °C. Maturation, harvest date, storage temperature, storage period and shelf-life affect the concentrations of sugars and organic acids in Japanese plums.     

不同模拟流通温度对桃果实硬度和糖酸品质的影响

为了研究常温、冷链、断链3 种流通方式对桃果实品质的影响,在模拟3 种流通方式的温度环境下对桃果实进行贮藏,分析模拟流通过程中的桃果肉硬度、细胞壁果胶和糖酸含量及其组成的变化情况。结果表明,桃果实采后的贮运品质受流通温度的影响显著。模拟常温环境中流通的桃果实在4 d内即失去商品价值;恒定低温的流通条件（模拟冷链流通）可以保证桃果实在贮运期和货架期的良好品质;而模拟断链流通组的桃果实由于在贮藏过程中经历了包装、出入库等环节的温度升高,在进入货架期后果实品质快速下降,货架期第2天的果肉硬度（2.14 g/cm2）、蔗糖含量（46.48 mg/g）和苹果酸含量（3.13 mg/g）显著低于模拟冷链流通组（P＜0.05）。桃果实采后冷链流通过程应尽量避免贮运环节断链造成的温度变化,研究结果可为果蔬冷链流通系统的完善提供参考。     

热激处理对冷藏“解放钟”枇杷果实木质化及相关酶活性的影响

以福建莆田市“解放钟”枇杷为材料,采后50℃热处理30min 后分为冷库(2～5℃)和室温(18～25℃)两种贮藏条件进行贮藏。在贮藏期通过对枇杷果实的木质素含量、硬度、多酚氧化酶(PPO) 、苯丙氨酸解氨酶(PAL)、肉桂醇脱氢酶(CAD)、过氧化物酶(POD)活性变化的分析,研究贮前热处理对冷藏枇杷果实木质化及相关酶活性的影响。结果表明：低温(2～5℃)条件下贮藏,枇杷果实硬度和苯丙氨酸解氨酶活性都有明显升高,且两者呈正相关,相关系数r=0.914。贮前热处理能够延缓冷藏枇杷果实木质素含量及硬度的上升,降低PPO、PAL、CAD、POD 的活性。     

Organic acids of various kinds of vegetables. IV. Changes in the acids and sugar in tomatoes, sweet peppers and cucumbers during development and ripening

Concentrations of organic acids and sugars in tomatoes and sweet peppers change notably during ripening. The concentration of malic acid decreases while that of citric acid increases considerably and in redripe fruits clearly exceeds the content of malic acid. Several maxima and minima in acid concentrations occur during development. Both species show constant proportions of citric and isocitric acid (200:1 and 30:1 respectively). In sweet pepper, quinic and ascorbic acid can be found in noticeably higher amounts than in tomatoes. Additionally, succinic acid was detected in tomatoes and fumaric and shikimic acid in sweet pepper. Glucose and fructose, in approximately equal amounts, are the main sugar components; their concentrations are increased during ripening, especially in sweet peppers. The leaves of tomatoes and sweet pepper contain more malic acid and less citric acid than redripe fruits, though here as well citric acid predominates. There is considerably less glucose and fructose present in the leaves of sweet pepper than in the fruits while sucrose is increased. Sucrose is the main sugar component in the leaves. Compared to tomatoes and sweet peppers, egg-plants contain more amounts. - Potatoes contain citric, malic, quinic, succinic, fumaric, and soluble oxalic acid (in order of decreasing amounts). - In cucumbers malic acid notably exceeds citric acid. Both acids hardly change in concentration during ripening. Sugar content decreases during ripening.     

Reduction of chilling injury in ripe Alphonso mango fruit in cold storage by temperature conditioning

The influence of ripening temperature and cold conditioning of pre-climacteric fruits on the incidence of chilling injury (CI) in ripe mango fruits cv. Alphonso during refrigerated storage was investigated. Fruits previously held and ripened at tropical ambient temperature (AT, 27–34°C) developed CI (skin staining or browning) when ripe fruits were subsequently stored at 5, 10, or 15°C for shelf-life extension. Fruits held and ripened at 20°C1°C, RH 85–90% showed little evidence of CI when subsequently stored at 5 or 10°C up to 14 days. Chilling injury in ripe mangoes was also avoided by holding pre-climacteric fruits for a minimum period of 30 days at 10°C and then ripening them at 27–34°C. The quality of the ripe mangoes remained good during cold storage for 7 days and were acceptable until 10–14 days with minimal changes in texture, flesh colour, carotenoids, total soluble solids, titratable acids and ascorbic acid. Shelf-life of ripe mangoes can thus be extended under refrigeration by pre-storage conditioning.     

采前水杨酸处理对杏果实抗病性及苯丙烷代谢的诱导

以新疆赛买提杏为试材,在果实坐果期、膨大期、转色期及采收前48 h的4 个时期,采用1.0 mmol/L水杨酸对杏果实进行喷施处理,以喷清水处理作为对照。采收后的杏果实置于4 ℃、90%～95%相对湿度条件下贮藏,定期统计杏果实接种链格孢（Alternaria alternata）的病斑直径和接种发病率,测定苯丙氨酸解氨酶（PAL）、肉桂酸羟化酶（C4H）、4-香豆酰-辅酶A连接酶（4-CL）的活性及木质素、总酚和类黄酮的含量,研究采前水杨酸处理对杏果实抗病性和苯丙烷代谢关键酶活性及代谢产物积累的影响。结果显示：采前水杨酸处理能有效降低杏果实损伤接种的病斑直径和接种发病率,显著提高杏果实PAL、C4H、4-CL的活性和木质素、总酚、类黄酮的含量。     

1- 甲基环丙烯对李果实冷藏及货架期非挥发性风味物质的影响

使用多变量分析方法研究1-MCP对‘黑琥珀’李果实0℃贮藏和随后的20℃货架期间非挥发性的糖、有机酸和氨基酸的影响。单因素试验结果表明：低温贮藏期间,李果实蔗糖和苹果酸含量逐渐下降,D-果糖含量先降后升,其余组分均在贮藏67d时达到释放高峰;货架期间,96d后的货架期非挥发性组分含量均达到高峰。主成分分析结果表明：与出库时相比,冷藏67d后的货架9d时各组分含量均降低,而贮藏后期的货架9d时则升高;冷藏67d时及冷藏96d后的货架期,1-MCP处理均显著降低了糖、酸类物质的峰值,减缓了糖、酸物质的代谢速率,维持了冷藏期间的营养品质并延缓了货架期的品质劣变。偏最小二乘和通径分析结果表明：D-果糖与感官甜酸比呈显著正相关,是主要的直接与间接因子;苹果酸对感官酸度和可溶性固形物(SSC)均有显著正相关性,且对SSC主要通过D -葡萄糖的间接效应来实现;山梨糖醇与pH值呈极显著负相关。     

Internal quality and antioxidants content of cold-stored red sweet peppers as affected by polyethylene bag packaging and hot water treatment

Physical (weight, firmness) and compositional (sugars, organic acids, ascorbic acid, phenolic compounds and carotenoids) changes of red sweet peppers (Capsicum annuum L.) were monitored during 21 days of cold storage (at 7.5 °C); fruits were stored without packaging, packaged in low density polyethylene bags, or after hot water dipping (53 °C for 4 min) and packaging. Packaging prevented water loss, and preserved the firmness of the fresh product. Sugars (fructose and glucose) content was practically constant throughout the whole storage time, for all treatments. A moderate accumulation of citric acid was observed during storage, but no marked effects of packaging and hot water dipping on citric and malic acid content. Ascorbic acid content slightly increased in unpackaged and packaged fruits, but not in treated+packaged peppers. Hydroxycinnamics total content seemed not to be affected by cold storage, packaging or hot water treatment, whereas glycosylated flavonoids showed somewhat lowered levels during storage, particularly in the case of unpackaged and packaged+treated fruits. Regarding carotenoids content, the effect of the considered storage conditions seemed to be much smaller than that due to ripening stage. Provitamin A content showed an increasing trend in unpackaged and packaged fruits; packaged+treated peppers were characterised by a lower retention of provitamin A and a higher level of capsanthin and cucurbitaxanthin A with respect to not treated fruits. On the whole, packaging and hot water treatment did not produce noticeable adverse effects on the majority of the examined compositional quality parameters.     

Effects of postharvest treatments on fruit quality of sweet pepper at low temperature

BACKGROUND: Postharvest storage of sweet pepper fruits (Capsicum annuum L.) at low temperatures could impair their physical and chemical composition. Therefore, maintenance of essential nutrition support or altered gas exchange could preserve fruit quality, minimizing chilling injury. Thus our aim was to determine the response to postharvest application of a low concentration of nitrogen (urea) or antitranspirant (pinolene) during a period of 21 days at 5 °C. RESULTS: The results indicate that storage at 5 °C was effective with respect to maintaining firmness of sweet pepper fruits for 21 days, while application of antitranspirant increased firmness compared with non‐sprayed fruits. Additionally, urea maintained color while increasing total phenolics and the activity of catalase and ascorbate peroxidase, lowering lipid peroxidation. Composition of free amino acids was affected to a minor extent. CONCLUSION: Maintaining quality is of paramount importance in the postharvest period. This study shows the effect of both temperature and spraying treatments with regard to maintaining fruit quality during this period, and provides new insights into the physiological role of enzymes of the antioxidant system during pepper storage at low temperature. Copyright © 2010 Society of Chemical Industry     

胡椒提取物在冷却肉保鲜中的应用

研究胡椒提取物作为复合保鲜剂的成分在延长冷却肉货架期方面的作用。采用常压回流方法获得胡椒提取物,再以胡椒提取物、壳聚糖和乙酸为试材,对冷却肉进行贮藏保鲜,最后采用二次通用旋转组合设计法,对复合保鲜液配方成分的比例进行优选。结果表明：复合保鲜剂能明显地抑制保藏过程中微生物的生长。胡椒提取物质量分数0.95%,壳聚糖质量分数0.99%,乙酸质量分数0.80%的保鲜剂配方较好,保鲜12d后细菌总数(lg(CFU/g))为5.2214。     

CHILLING INJURY IN GREEN BANANA FRUIT: CHANGES IN PEROXIDASE ISOZYMES IN SOLUBLE AND PARTICULATE POOLS

Green banana fruit manifested severe chilling injury after 5–7 days storage at 5°C and 80% relative humidity. (Severe chilling injury is described here as a failure of the fruit to ripen on removal to conditions conducive to normal ripening.) The recoverable "wall bound" peroxidase fraction exhibited a sharp decline during this initial period of stress. Subsequent storage of severely chilled fruit at. 5°C resulted in a gradual increase in the "soluble" peroxidase pool and a rise in "wall bound" peroxidase to levels comparable to normal green fruit. After 30 days storage of fruit at 5°C the "soluble" and "wall bound" fractions of peroxidase peaked and declined rapidly in the latter pool. The increase in peroxidase of cold stressed fruit involved qualitative changes in isozyme species that differed from those isozymes which emerge during normal fruit ripening. It is suggested that the initial decrease in "wall bound" peroxidase results in a loss in capability of the tissue to adapt to low temperature stress. The belated increase in peroxidase activity may be associated with a typical "cold hardening" response which develops only after an irreversible or "plastic strain" damage has occurred     

臭氧处理对黄花梨果实褐变的影响

为研究臭氧处理对梨果实褐变的影响,采用5.0、2.5mg/L 臭氧水和蒸馏水浸泡黄花梨整果和鲜切果,5min后晾干,分别贮于20℃和5℃条件下,对贮藏过程中果实和切片的褐变指数、总酚(TP)含量及与酶促褐变相关的多酚氧化酶(PPO)、过氧化物酶(POD)和苯丙氨酸解氨酶(PAL)活性变化进行研究。结果表明：臭氧处理的黄花梨整果与鲜切果各项指标均优于对照组;臭氧处理显著降低贮藏5d 后黄花梨整果果心和整个贮藏期鲜切片的褐变指数,维持梨整果与鲜切果较高的总酚含量,对二者PPO、POD 活性均有一定的抑制作用;可增加梨整果较高的PAL 活性,抑制鲜切梨果PAL 活性。抑制黄花梨整果和鲜切果褐变以2.5mg/L 臭氧水处理为好。     

果蔬冷害化学控制技术研究进展

低温贮藏是延长果蔬保鲜期最为有效的保鲜方式之一。但冷敏性果蔬低温贮藏时容易产生冷害,严重影响果蔬品质,是限制果蔬保鲜期的主要影响因素。为控制冷藏果蔬冷害发生、延长其保鲜期提供的实用技术措施,本文综述了果蔬冷害发生的症状及化学方法控制果蔬冷害发生的研究进展,包括1-甲基环丙烯、茉莉酸甲酯、γ-氨基丁酸、一氧化氮、甜菜碱、草酸、苹果酸、水杨酸等化学物质在果蔬冷害防控中的应用。     

Changes in red pepper antioxidants as affected by UV-C treatments and storage at chilling temperatures

Chilling injury (CI) is one of the main factors limiting refrigeration in several horticultural commodities of subtropical and tropical origin such as pepper. Short UV-C treatments before low temperature storage have been shown to reduce CI. In this work we wanted to test whether or not the reduced susceptibility to CI in UV-C treated fruits was associated with increased levels of antioxidant compounds and enzymes. Red peppers (Capsicum annuum L.) were treated with UV-C radiation (10 kJ/m²) and stored at 0 °C for 21 d. During storage we analyzed chilling injury development, ascorbic (AA) and dehydroascorbic acids and DPPH radical scavenging capacity. We also followed superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) activities. CI increased rapidly when the fruit was stored for longer than 14 d, but was significantly lower in UV-C treated peppers. Exposure to UV-C did not alter fruit color but reduced weight loss. Although AA and DPPH radical scavenging capacity were lower in the control, this occurred towards end of storage, when CI was already advanced. In contrast, SOD, CAT and APX activities were higher in UV-C treated fruits during the first 2 weeks of storage when the symptoms became visible. Results show that UV-C exposure prevents CI and weight loss in red pepper and suggest that this might be related to increased activity of antioxidant enzymes.     

Accumulation of lignin and involvement of enzymes in bamboo shoot during storage

Fresh bamboo (Phyllostachys praecox f. prevernalis.) shoots were harvested, and the changes of firmness, electrical conductivity (EC), respiration rate, ethylene production, total sugars (TS), reducing sugars (RS), lignin and cellulose content and the activity of phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD) and peroxidase POD were investigated during storage at 2 or 20°C for 30 or 12 days, respectively. EC increased quickly, with a more rapid rate at higher temperature, but it increased sharply after 24 days at 2°C. Respiration rate increased slowly at 20°C, while at low temperature (2°C) respiration rate and ethylene production significantly decreased. There was a quickly decrease in TS content at 20°C. Shoot firmness, lignin and cellulose increased and accelerated by higher storage temperature during storage at 2 or 20°C. Shoots firmness showed a positive correlation with accumulation of lignin and cellulose in the flesh. Among the enzymes associated with lignin synthesis, PAL and CAD activity showed a persistent rise over the whole 12 days, while POD activity increased rapidly within 6 days during storage at 20°C, followed by a slowly decrease. Accumulation of lignin in flesh tissue was also positively correlated to activity of PAL, CAD and POD. Our results suggest that the increase in firmness of bamboo shoots during storage is a consequence of tissue lignification, a process associated with increases in PAL, CAD and POD activity.     

Enzymes associated with blackheart development in pineapple fruit

The involvement of browning enzymes, polyphenoloxidase (PPO), peroxidase (POD) and phenylalanine ammonia-lyase (PAL) in blackheart development was investigated in pineapple fruit (Ananas comosus, Smooth Cayenne) following low temperature storage. An increase in PPO activity was related to the incidence of blackheart symptoms, both temporally and spatially. Fruit maturity significantly affected blackheart susceptibility; immature and over-mature fruits developed less blackheart injury than mature fruit. The effect of maturity on blackheart susceptibility was highly correlated to the response of PPO activity to chilling. POD showed no significant change after chilling. Enhanced PAL activity was observed during chilling at 6, 13 and 18 °C. Chilling (6, 13 and 18 °C) also inhibited the increase of ascorbate peroxidase activity observed in the fruit stored continuously at 25 °C, but had less effect on catalase activity. The results indicate that the development of blackheart symptoms in pineapple fruit results from the disturbance of a number of metabolic processes that occur at sub-ambient temperatures.     

草酸对桃贮藏期抗性相关酶活性的诱导

以栽培品种“皮球桃”为试材,采后以草酸溶液浸泡处理后,置于温度为(1 ± 1)、(4 ± 1)、(8 ± 1)℃的气调库贮藏,测定贮藏过程中部分抗性酶的活性以及丙二醛的含量,探讨草酸、温度等对气调贮藏条件下的皮球桃采后抗性生理的影响。结果表明：与对照组相比,草酸处理能提高桃果SOD、CAT 的活性,在贮藏中后期提高PPO 的活性,对POD 没有直接影响,并使MDA 的积累得到控制。以草酸(1 ± 1)℃的处理组的效果最为明显,说明草酸和低温能在一定程度上提高桃果实的抗性。