Combined effects of 1-methylcyclopropene, calcium chloride dip, and/or atmospheric modification on quality changes in fresh-cut strawberries

The aim of this study was to determine the effects of 1-methylcyclopropene, 1-MCP (1 μL L⁻¹ for 24 h at 5 °C) on quality attributes and shelf life of fresh-cut strawberries. The 1-MCP was applied before (whole product) and/or after cutting (wedges), followed by storage in a continuous flow of air or air +1 μL L⁻¹ C₂H₄. The combined effects of 1-MCP and CaCl₂ dips (1% for 2 min) and/or CA (3 kPa O₂ + 10 kPa CO₂) were also examined. The application of only 1-MCP before and/or after cutting did not have a significant effect on firmness and appearance quality during storage for up to 12 days at 5 °C. The exposure to a continuous flow of 1 μL L⁻¹ C₂H₄ in air during storage did not increase the softening rate. 1-MCP applied before cutting or both before and after cutting of the strawberries increased respiration rates but reduced C₂H₄ production rates. Exposure to 1-MCP had a synergistic effect when combined with CaCl₂ plus CA. The combined treatment of 1-MCP + CaCl₂ + CA slowed down softening, deterioration rates, TA and microbial growth. Compared to the control, which had a 6-day shelf life, the shelf life of fresh-cut strawberries subjected to the combination treatment was extended to 9 days at 5 °C.     

Greenhouse climate control affects postharvest tomato quality

In this study, important quality properties such as firmness, sugar and acid levels were measured and analysed in tomatoes harvested from three greenhouses during a five month period and stored at 16 °C for over 20 days. Tomatoes were harvested from three identical, neighbouring, greenhouses which were either conventionally ventilated (open greenhouse) or mechanically cooled (semi-closed greenhouses). Sugar and acids levels were hardly affected by greenhouse type. Compared to the open greenhouse, semi-closed greenhouses produced heavier and less mature (firmer) fruit at the commercial harvesting stage based on colour. Fruit maturity differences could be linked to the vertical temperature gradient and to CO₂ levels in the different greenhouses. This indicates that CO₂ levels and temperature affect the synchronisation between colour and firmness maturity at harvest. The acceptance period, i.e., the time period both tomato colour and firmness are considered acceptable by consumers, will likely be positively affected when growers switch from conventionally ventilated to semi-closed production systems. Additional to greenhouse effects also effects of the harvest month were observed. The sugar to acid ratio was highest and glucose to fructose ratio was lowest in July, the month with the highest irradiance, irrespective of greenhouse type. The estimated value for the maximum firmness (F_max) varied from 17.9 N in August to 31.2 N in June. This monthly variation in F_max explains an important part of the variation found in the postharvest behaviour of tomatoes. Interestingly, the monthly variation in F_max showed the same trend as found for the monthly initial sugar levels. It might be hypothesised that the monthly variation in glucose and fructose levels causes variation in that part of firmness that is generated by cell turgor. The monthly variation in F_max, sugar and acid levels could not be linked to climate conditions and remains to be elucidated.     

Aloe vera gel coating maintains quality and safety of ready-to-eat pomegranate arils

Several postharvest treatments were performed on pomegranate arils prior to storage in rigid polypropylene boxes for 12 days at 3 °C: water (control), ascorbic + citric acids (at 0.5 or 1%), Aloe vera gel (at 50 or 100%), 50% A. vera gel + 0.5% ascorbic and 0.5% citric acid, and 100% A. vera gel + 1% ascorbic and 1% citric acid. A. vera (alone or in combination with acids) led to lower CO₂ and higher O₂ concentrations inside the packages compared with arils treated with water (control). With respect to quality attributes, A. vera coatings led to firmness retention and increased levels of total anthocyanins and total phenolics. In addition, A. vera treatments led to significantly lower counts for both mesophilic aerobics and yeast and moulds. Sensory analysis scores for flavour, texture, aroma, colour and purchase decision were higher in arils treated with A. vera, especially in those arils treated with 100% A. vera + 1% ascorbic and citric acids. Finally, no off-flavours in pomegranate arils were perceived by judges as a consequence of A. vera gel treatment.     

Controlled Atmosphere Storage of Sweet Cherries (Prunus avium L.)

Sweet cherry (Prunus avium L.) cultivars 'Emperor Francis', 'Huldra', 'Sam', 'Stella', 'Kristin', and 'Van' were stored in controlled atmosphere (CA) during one, two or three seasons. The cherries were held at a temperature of 0°C, or 2°C for up to three weeks. The fruit quality was evaluated on juice optical density (OD), titratable acidity (TA), pH, soluble solids content (SSC), ethanol, firmness and flavour. In general, CA had little effect on SSC in the three seasons and did not show any effects in reducing pitting. Controlled atmosphere has shown some beneficial effects on flavour, reducing decay, reducing toughening, and maintaining TA in sweet cherries. Generally, flavour score was higher for fruit kept in CA than for fruit stored in air, and the higher the CO₂ the better the taste. 'Van' and 'Sam' showed excellent taste scores after three weeks both from CA and air storage. There was very little ethanol accumulation in the fruits under CA, and it was well below the detrimental level. It is recommended that O₂ levels for sweet cherry storage can be further reduced below 10% and/or CO₂ can be increased above 15%.     

Effects of NaCl application to hydroponic nutrient solution on fruit characteristics of tomato (Lycopersicon esculentum Mill.)

NaCl was applied to nutrient solution (5 dS m⁻¹ versus 1.4 dS m⁻¹ in the control) of hydroponically-grown tomato and its effects on taste grading and chemical composition of fruit were investigated. Taste panels indicated NaCl treatment increased sweetness, acidity, umami (i.e. the taste of deliciousness) and overall preference. Hexose concentration of the fruit grown on NaCl treated plants significantly increased; and at the same time, chloric ion, organic and amino acids in general had higher concentrations in NaCl treated plants than the control. Our results showed that (1) consumer grading of the tomato fruit was influenced not only by sugar content but also by the organic and amino acids; (2) increased concentration of soluble solids in the fruit of NaCl treated plants was not the result of simple overall condensation due to the reduction of water transport. The relation of diversified consumer preference, fruit chemical composition, and appropriate evaluation of tomato fruit are also discussed.     

Effects of deficit irrigation on fruit maturity and quality of ‘Braeburn’ apple

Effects of deficit irrigation (DI) on fruit maturity at harvest, ripening characteristics, and changes in fruit quality during and after storage of ‘Braeburn’ apple (Malus domestica Borkh.) were studied in two experiments. In Experiment 1, irrigation treatments were a commercially irrigated control (CI), an early deficit irrigation (EDI) applied from 63 to 118 days after full bloom (DAFB), and a late deficit irrigation (LDI) applied from 118 DAFB to final harvest on 201 DAFB. Irrigation treatments in Experiment 2 were a commercially irrigated control (CI) and a whole-season deficit irrigation (WDI). These DI treatments all reduced volumetric soil water content. The LDI and WDI advanced fruit ripening but EDI did not. All DI treatments increased fruit total soluble solids (TSS) and firmness regardless of maturity but had little or no effect on titratable acidity. The differences in TSS started during fruit growth much earlier than the onset of ripening and were maintained during and following storage at 0°C. The differences in firmness also started during fruit growth and were maintained for at least 10 weeks of storage at 0°C.     

‘乔纳金’苹果采后1-MCP 处理对常温贮藏效果的影响

 试验结果表明, 1-MCP (1 - 甲基环丙烯) 处理可以明显降低‘乔纳金’苹果果实的呼吸强度,延迟呼吸高峰的出现, 明显减缓硬度和酸度的下降, 减少叶绿素的分解, 但低浓度的1-MCP 处理增加了苦痘病的发生率。     

不同处理条件下1-MCP对金冠苹果呼吸强度和品质的影响

以金冠苹果为试材,1-MCP处理后,研究了采收期、处理时间、处理温度和处理时期对果实采后呼吸强度和品质的影响。结果表明,1-MCP处理显著降低了果实的呼吸强度,延迟了果实呼吸高峰的出现,与对照果实相比,1-MCP很好地保持了果实的风味和品质。不同采收期、处理时间的长短、处理温度和处理时期均对1-MCP的作用效果有影响,在这些因素中,采后处理时期对1-MCP作用效果的影响最大。     

柿果软化过程中几种生理指标的变化

[目的]探索柿果软化过程中呼吸速率、乙烯释放量及蛋白酶含量的变化规律。[方法]以我国主栽涩柿品种＂磨盘柿＂为试验材料,研究磨盘柿采后贮藏过程中中呼吸速率、乙烯释放量、蛋白酶含量与果肉硬度变化间的关系。[结果]随着柿果硬度的降低,呼吸速率和乙烯释放量均呈先上升后下降趋势,蛋白酶含量总体呈下降趋势。[结论]柿果软化是多因素共同作用的结果。     

Influence of aqueous 1-methylcyclopropene concentration, immersion duration, and solution longevity on the postharvest ripening of breaker-turning tomato (Solanum lycopersicum L.) fruit

The influence of aqueous 1-methylcyclopropene (1-MCP) concentration, immersion duration, and solution longevity on the ripening of early ripening-stage tomato (Solanum lycopersicum L.) has been investigated. Tomato fruit at the breaker-turning stage were fully immersed in aqueous 1-MCP at 50, 200, 400 and 600 μg L⁻¹ for 1 min, quickly dried, and then stored at 20 °C. Ethylene production, respiration, surface color development, and rate of accumulation of lycopene and polygalacturonase (PG) activity were suppressed and/or delayed in fruit exposed to aqueous 1-MCP. Suppression of ripening was concentration dependent, with maximum inhibition in response to 1 min immersion occurring at concentrations of 400 and 600 μg L⁻¹. Climacteric ethylene peaks were delayed approximately 6, 7, and 9 d and respiration was strongly suppressed in fruit treated with aqueous 1-MCP at 200, 400, and 600 μg L⁻¹, respectively, compared with control fruit. Fruit firmness, lycopene content, PG activity, and surface hue of fruit treated at the three higher levels remained strongly suppressed compared with control. Skin hue values and pericarp lycopene content in response to treatment at the subthreshold 50 μg L⁻¹ provided evidence for differential ripening suppression in external versus internal tissues. Maximum delay of softening and surface color development in response to 50 μg L⁻¹ aqueous 1-MCP occurred following immersion periods of between 6 and 12 min. Factors affecting fruit penetration by aqueous 1-MCP and mechanisms contributing to recovery from 1-MCP-induced ripening inhibition are discussed.