Overcoming adverse effects of hailnets on fruit quality and microclimate in an apple orchard

BACKGROUND: With the increase of hailstorms as a possible result of global warming, fruit crops are increasingly grown under hailnets. This results in lesser fruit quality in terms of colouration, fruit mass, firmness, starch and taste, i.e. sugar and acid, and vitamin content under hailnet due to altered microclimate and light deprivation. Reflective mulches (Extenday and Daybright) were spread in autumn 2006 to improve fruit quality and light utilisation under hailnet at Klein‐Altendorf Research Station near Bonn, Germany. A monophosphate (Seniphos) was applied twice for the same purpose; untreated apple cv. ‘Elstar’ trees served as control. RESULTS: Under the translucent, ‘white’ hailnet, humidity was increased by ca. 6%, air temperature reduced by ca. 1.6 °C, soil temperature increased by ca. 0.5 °C and light reduced by 11–15% resulting in lesser fruit quality of 2.5% less sugar and less taste. The two reflective mulches increased light reflection at 45° and 90° angles by 2.5‐ to 6.3‐fold. No differences in fruit ripening and firmness were observed, but fruit from trees under hailnet with reflective mulch contained up to 2.4% (from 13.3 to 15.7%) more sugar than those of the control (uncovered grass alleys). A less negative normalised differential vegetation index (NDVI) of ? 0.3 on the red compared with ? 0.5 on the green fruit side indicated more chlorophyll in the outer, sun‐exposed, red side of the apples relative to the shaded side. Monophosphate‐treated fruits maintained the peel chlorophyll with a greener ground colour of 92–97° hue and a NDVI of ? 0.3 as in the grassed control. Fruit in the lower canopy with reflective mulch were darker red (a value 30; 22° hue) relative to the grassed control with a = 25 and 43° hue (light red), expressed in a 4‐fold increase in normalised anthocyanin index (NAI), but showed enhanced chlorophyll breakdown (NDVI from ? 0.2 to ? 0.5); similarly, the monophosphate increased the NAI by up to 2.5‐fold. CONCLUSIONS: The effect of both reflective mulch cloths was most pronounced on apple fruit in the lower canopy under hailnet, which developed large vitamin C contents and a dark red top colour relative to the grassed control with enhanced chlorophyll breakdown. Both reflective mulch cloths increased the percentage of class I fruit with > 25% colouration by 12% (from 82 to 94%) without and under hailnet by 23% (from 69 to 89%) relative to the grassed control resulting in financial net gains of up to 1300 € ha^?1 Copyright © 2007 Society of Chemical Industry     

EFFECTS OF THE RATE OF HEATING ON APPLE AND PEAR FRUIT QUALITY

There is evidence that the rate of heating to meet quarantine security impacts fruit quality as well as insect mortality. Linear heating rates, of 4, 6, 8, 10, and 12C/h to treatment temperatures of 44 and 46C were used to treat 8 cultivars of apples (‘Delicious’, ‘Golden Delicious’, ‘Granny Smith’, ‘Fuji’, ‘Gala’, ‘Jonagold’, ‘Braeburn’, and ‘Cameo’) and two cultivars of winter pear (‘d'Anjou’ and ‘Bosc’). Fruit were stored, ripened, and tested for various quality parameters. Scald was controlled, firmness was higher in heat treated fruit, ripening was delayed but uniform in pears, decay organisms were suppressed, red fruit became redder and green fruit remained green, the Brix‐acid ratio (SS/TA) was either unchanged (‘Granny Smith’) or increased. Physiological disorders such as bitter pit were exacerbated by the heat treatment, requiring culling after treatment to avoid storage of fruit so affected.     

Relationship between soil temperature and fruit colour development of ‘Clemenpons’ Clementine mandarin (Citrus clementina Hort ex. Tan)

BACKGROUND: In Citrus, root temperature regulates rind colouration. However, few studies have investigated the range of temperatures and timing which determine rind colour break. The objective of this study was to determine the relationship between range of soil temperature (ST) and rind colour development in the precocious ‘Clemenpons’ Clementine mandarin. Reflective white plastic mulch was used to modify root temperature. RESULTS: Mulching increased reflected light and reduced daily maximum ST and temperature range, major differences being established 70–30 days before harvest. Rind colour‐break correlated positively with 20 °C < ST < 23 °C; thus, 20–23 °C appears to be the ST threshold interval for fruit colouration. The sooner the soil reached it, the sooner the fruit changed rind colour. In our experiments, control trees accumulated 565 h at this ST interval before fruit changed colour, whereas in treated trees it occurred 2 weeks earlier. Hence, in treated trees the colour break was advanced by 2 weeks and this increased the percentage of fruit harvested at the first picking date by up to 2.5‐fold. Conclusions: Fruit colour‐break does not take place at a certain ST, but after several hours at a ST of 20–23 °C. In our experiments, reducing ST during the 2 months before harvest advances the first picking date in the ‘Clemenpons’ Clementine mandarin. Copyright © 2011 Society of Chemical Industry     

Can coloured hailnets improve taste (sugar, sugar: acid ratio), consumer appeal (colouration) and nutritional value (anthocyanin, vitamin C) of apple fruit?

Envisaged photo-selective effects, as reported for kiwi and grapevine, of white, red-white, red-black and green-black hailnets were investigated in apple cvs ‘Pinova’ and ‘Fuji Kiku 8’ near Bonn, Germany in 2007; uncovered trees served as control. Light transmission of green or red hailnets peaked at 490-610 nm (green) or above 610 nm (red-orange), was reduced by ca. 12% or 14% by white or red-white, respectively, and by 18% or 20% by red-black and green-black hailnets. Air temperature under coloured hailnets was decreased by an averaged 1.3 °C and humidity increased by 2-5% rh. The peel of apples under coloured hailnets contained more chlorophyll (NDVIndex), but 4-5-fold less anthocyanin (NAIndex). The greater sugar (up to 0.7 g/100 g TSS) and acid content, i.e. the better fruit quality and consistent taste (sugar: acid ratio), the firmer fruit (by up to 0.6 or 0.8 g/100 g TSS in ‘Fuji’ or ‘Pinova’) with advanced starch breakdown and improved colouration (NAI) under the red-white and white hailnets was attributed to more light than under the red-black and green-black hailnets; hence, white hailnets appear a compromise to obtain good quality and healthy fruit and still protect the plants against sunburn and adverse weather conditions such as hail.     

Bioactive components in forced sweet cherry fruit (Prunus avium L.), antioxidative capacity and allergenic potential as dependent on cultivation under cover

Five early maturing varieties of Prunus avium L. on dwarfing rootstock were forced at Bonn, Germany in spring under transparent plastic cover without additional heating to ripen at a time before field-grown German fruit become available, with better fruit quality than imported sweet cherries; trees grown outside without cover served as control. The cover reduced the incident radiation by up to 54% PAR, UV by up to 22% UV-A and UV-B up to 2% and increased day temperature indoors. Fruit were as firm in the early varieties grown under cover as those in the field and slightly softer than in the late harvesting cultivars. Sugar content was slightly less in four of the five varieties; no differences in acidity and sugar/acid ratio as a taste indicator were found. Fruits were up to 3 mm larger when grown under cover in cvs. ‘Burlat’ and ‘Souvenir’, but no differences were observed in cvs. ‘Earlise’ and ‘Prime Giant’. Fruit of three cultivars, ‘Burlat’, ‘Samba’ and ‘Prime Giant’ can be classified as premium quality with 28 mm–30 mm diameter, when grown under cover. Overall, all cherry fruit were of the market, i.e. consumer- preferred, dark red colouration in line with enhanced anthocyanin contents. In two cultivars, the cover induced healthier fruit. Antioxidative capacity was larger in cv. ‘Samba’, while ascorbic acid (Vitamin C) was increased in cv. ‘Souvenir’; phenols were enhanced in all cultivars and attributed to heat stress. Allergenic protein (Pru av 1) in cherry fruits of both cultivation types were below the detection level at harvest time, indicating that cultivation under cover had no adverse effects on this particular health component.Overall, forcing successfully resulted in 2 weeks earlier ripening, thereby providing the first fresh and healthy (low allergen, high phenolic compounds and high anthocyanin) German cherries of high fruit quality on the market in spring.     

Comparative study of improved vs. traditional apple cultivars and their aptitude to be minimally processed as ‘ready to eat’ apple wedges

The development of fresh-cut apple products requires the reconsideration of cultivar selection because different characteristics are required compared with those characteristics for the fresh market. The aim of this work was to evaluate four improved cultivars (‘Modì’, ‘Ariane’, ‘Fuji Kiku 8’ and ‘Pink Lady’) and to compare these cultivars with traditional cultivars (‘Golden Smoothee’ and ‘Granny Smith’). Cultivars were evaluated according to physicochemical parameters and nutritional, enzymatic, and sensory aspects. Next, the cultivars were peeled, cut, treated with different antioxidant treatments, packaged in polypropylene trays and stored at 4 °C. After seven days of storage, physicochemical parameters and visual assessment were determined. As whole apples, the improved cultivars were notable for their sensory characteristics. Moreover, two of them (‘Modì’ and ‘Ariane’) presented the highest amount of total phenols and vitamin C, respectively. After processing and storage, certain of the improved cultivars presented better aptitude for minimal processing. For instance, ‘Modì’ showed high suitability, and ‘Fuji Kiku 8’ was notable for its sensory quality after seven days of refrigerated storage. Among antioxidant treatments that were assayed, 40 g/L NatureSeal^® demonstrated the best results in terms of physicochemical parameters, visual assessment and sensory quality.     

Effect of location in the canopy on the colour development of three apple cultivars during growth

BACKGROUND: Homogeneity in appearance is one of the quality aspects asked for in the supply chain. Decreasing the biological variation in batches of harvested apples (cultivars Braeburn, Fuji and Gala) becomes increasingly important. Skin colour is one of the aspects that determine both optimal harvest and stage of development. Skin colour is affected by location in the canopy. The rules of development of biological variation are now established and will be used on skin colour data. RESULTS: The Minolta colour aspects a*, b* and L* measured before commercial harvest change in a sigmoidal fashion and can be analysed including the biological variation, with a logistic model in indexed nonlinear regression, obtaining explained parts of above 90%. The mechanism of colour change is not affected by state of development or location in the canopy. The location in the canopy affects the intensity of both red and green colouring compounds. The variation in colouration is not affected by the location in the canopy. CONCLUSION: The red‐coloured apple cultivar (Gala) depends more on the location in the canopy than the less‐coloured cultivars (Fuji and Braeburn). The colour development in Fuji apples is considerably slower, with a much larger variation in stage of development. The location in the canopy affects all aspects of biological variation (biological shift factor and asymptotic starting level of colouration) for all three colour aspects L*, a* and b*, but only the mean value, not the standard deviation. The biological shift factors per colour aspects are linearly related. Once induced, variation remains constant during development. Copyright © 2012 Society of Chemical Industry     

新疆吐鲁番地区不同品种甜瓜营养成分分析及品质综合评价

以新疆吐鲁番地区种植的8个甜瓜品种（纳斯蜜、花玫、风味5号、风味8号、西州密17号、西州密25号、比谢克辛、俊秀）的成熟果实为试材,通过测定主要的营养品质指标及功能活性指标,对甜瓜果实品质进行比较及综合评价。结果表明,8个不同品种甜瓜果实品质之间有较为明显的差异,纳斯蜜的维生素C、可溶性固形物、可溶性蛋白质、蔗糖、果糖、葡萄糖的含量较高;花玫的果肉较硬,且厚度宽、果形指数高;风味系列的两种甜瓜类黄酮含量高、DPPH、ABTS自由基清除率较其他甜瓜大;俊秀的单果重最高,维生素C含量最低;其他品种甜瓜的含量处于平均水平。主成分分析结果表明,可将评价甜瓜果实品质的指标用4个因子表示,可溶性固形物、维生素C、总酚、ABTS自由基清除率、柠檬酸、葡萄糖、果糖、葡萄糖和果形指数的含量可作为其营养价值评价的重要指标;通过聚类分析,将8个不同品种的甜瓜分为4大类,第1类为‘风味8号’和‘风味5号’,具有酸甜风味;第2类为‘西州密17号’、‘西州密25号’、‘比谢克辛’和‘纳斯蜜’,具有较高的营养价值;第3类为‘花玫’,果形指数最好;第4类为‘俊秀’,单果重与其他品种比较具有明显优势。综合评价显示‘纳斯蜜’果实品质最优,‘西州密25号’、‘花玫’、‘风味5号’和‘比谢克辛’较优,其余品种品质较差。     

Effect of Fruit Ripening Stage on Physico-Chemical Properties, Nutritional Composition and Antioxidant Components of Tomato (Lycopersicum esculentum) Cultivars

In this study, we investigated the effects of fruit ripening stage on the physico-chemical properties and nutritional contents of three greenhouse grown tomato cultivars (‘Monika’, ‘Isabella’ and ‘Cherry’). Significant changes (p?≤?0.05) occurred in fruit colour, total soluble solids, protein, fibre, ascorbic acid (vitamin C) and lycopene content at different stages of ripening. ‘Cherry’ tomato contained significantly (p?≤?0.05) higher total soluble sugar and several nutrients including fibre. However, the plum-type tomato cultivars (‘Monika’ and ‘Isabella’) contained higher vitamin C and lycopene than ‘Cherry’ tomato. In all tomato cultivars, it was found that up to 50% of final lycopene content occurred during the final phase (from red to deep red colour) of fruit ripening.     

Effect of nano‐ZnO‐coated active packaging on quality of fresh‐cut ‘Fuji’ apple

A novel nanopackaging was synthesised by coating polyvinyl chloride (PVC) film with nano‐ZnO powder, and its effects on the preservation quality of fresh‐cut ‘Fuji’ apple were investigated at 4 °C for 12 days. Compared with the control (PVC film), nanopackaging significantly reduced the fruit decay rate (P < 0.05), as well as decreased the accumulation of malondialdehyde (MDA) from 74.9 nmol g^?1 in the control to 53.9 nmol g^?1 in the nanopackaging. Cutting caused an increase in ethylene level, suggesting wound‐induced ethylene production, which was suppressed in nanopackaging. Both the polyphenoloxidase and pyrogallol peroxidase activities were decreased in nanopackaging fruit. The initial appearance of apple slices was retained, and the browning index was prevented in nanopackaging samples, which was only 23.9, much lower than the control of 31.7 on day 12. These results indicated that nano‐ZnO active packaging could be a viable alternative to common technologies for improving the shelf‐life properties of ‘Fuji’ apples as a fresh‐cut product.     

高寒荒漠区延后栽培葡萄品质分析

为评价鲜食葡萄在高寒荒漠区延后栽培条件下的品质表现,以适应性较好的8个品种为研究对象,测定葡萄感官品质、内在品质、功效成分和糖酸品质,采用主成分分析法对果实品质进行综合分析和评价。结果表明,‘红地球’和‘紫地球’单果质量10 g以上,果粒大,能够保持原有的大果特征;无核品种较有核品种果粒小;8个品种果实果形指数均> 1,呈长椭圆形,除绿色品种外,果实着色较深;果皮颜色越深的品种,果皮花青素、类黄酮、总酚含量越高。2个无核品种(‘红宝石无核’和‘紫甜无核’)和‘红地球’可溶性固形物含量较高,在21%以上;糖酸组分及含量方面,果实中的糖分主要是果糖和葡萄糖,蔗糖未检出;酒石酸和苹果酸是主要有机酸,柠檬酸和草酸含量极微。酸甜风味方面,‘红宝石无核’口感最甜,其次为‘红地球’,‘瑞都香玉’和‘紫地球’口感较淡,‘摩尔多瓦’口感偏酸。通过主成分分析法提取了5个独立的主成分,累计贡献率87. 396%,以主成分为评价指标,对浆果品质进行综合评价,‘红宝石无核’、‘红地球’和‘玫瑰香’果实综合品质最好。     

Effect of heat treatment on physiochemical,colour, antioxidant and microstructural characteristics of apples during storage

Changes in qualities of ‘Red Fuji’ and ‘Golden Delicious’ apples in response to different heat treatments (45 and 60 °C) following cold storage were investigated. Quality indices including firmness, titratable acidity, total phenolic content, antioxidant capacity, colour parameters and microstructure were measured. Results indicated heat treatment at both temperatures for 3‐h hastened loss of titratable acidity in ‘Red Fuji’ and ‘Golden Delicious’ apples, but maintained firmness in both cultivars. However, heat treatment at lower temperature (45 °C) best maintained total phenolic compounds and antioxidant capacity in ‘Red Fuji’ apples throughout storage, whereas there was no difference between heat treatments in ‘Golden Delicious’ apples. Examination by scanning electron microscope (SEM) revealed that the effect of heat treatment at different temperatures on ‘Red Fuji’ and ‘Golden Delicious’ apples was structurally different. Apple tissue that had been heat treated at elevated temperature (60 °C) for 3 h was associated with fractured cell walls and collapse of cells.     

Monomeric phenolics in different parts of high‐acid apple (Malus sieversii f. niedzwetzkyana (Dieck) Langenf): a promising source of antioxidants for application in nutraceuticals

The high‐acid apple (Malus sieversii f. niedzwetzkyana (Dieck) Langenf) possessing deep red peel and light red flesh is widely distributed in China. To determine if a useful apple variety is being ignored, the monomeric phenolic profiles and antioxidant activities of peel, flesh, pomace, whole fruit and juice were evaluated. The results were compared to those of ‘Fuji’ and ‘Granny Smith’ apples. The high‐acid apple possessing the highest total phenolic and anthocyanin contents among three apple varieties contained the most chlorogenic acid, phloridzin, epicatechin, ferulic acid, catechin, vanillic acid, p‐coumaric acid and caffeic acid. The extraction yields of phenolics (64%) and anthocyanins (89%) from the high‐acid apple to juice were the highest. The high‐acid apple possessing the greatest antioxidant activity had the strongest antihaemolysis activity, indicating that it could be used to produce juice and value‐added ingredient to assist in the prevention of chronic disease.     

Commercial quality, major bioactive compound content and antioxidant capacity of 12 cultivars of loquat (Eriobotrya japonica Lindl.) fruits

BACKGROUND: Modern consumers are increasingly interested in their personal health and expect the food they purchase to be tasty and attractive while being safe and healthful. The aim of this study was to determine the commercial quality, characterise the antioxidant capacity and quantify the major bioactive compounds of 12 cultivars of loquat fruits in order to establish a database for utilising these germplasm resources. RESULTS: Of the 12 cultivars, ‘Guanyu’ produced the biggest fruits, while ‘Tianzhong’ and ‘Bingtangzhong’ had the highest soluble solids content but the lowest titratable acidity. ‘Taipinghong’ was reddest in colour. Sucrose, fructose, glucose and sorbitol were the major sugars in loquat fruits, with the highest total sugar content being observed in ‘Bingtangzhong’ and ‘Tianzhong’. Phenolics and flavonoids were the main bioactive compounds and were abundant in ‘Tianzhong’ and ‘Zhaozhong’. ‘Taipinghong’ had the highest total carotenoid content, while ‘Qingzhong’ had the highest vitamin C content. ‘Tianzhong’, ‘Bingtangzhong’ and ‘Ninghaibai’ showed higher antioxidant activity than the other cultivars, as measured by assays of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2‐azino‐bis(3‐ethylbenzthiozoline‐6‐sulfonic acid) (ABTS) scavenging and ferric‐reducing/antioxidant power (FRAP). CONCLUSION: Commercial fruit quality, major bioactive compound content and antioxidant capacity varied greatly among the 12 cultivars. ‘Bingtangzhong’ and ‘Tianzhong’ were the highest‐ranking cultivars based on their good commercial quality and high nutritional value. The loquat fruits with higher total phenolic and flavonoid contents also had clearly higher antioxidant capacities. Copyright © 2011 Society of Chemical Industry     

Time of methyl jasmonate application influences the development of ‘Cripps Pink’ apple fruit colour

BACKGROUND: The effects of time and numbers of pre‐harvest sprays of methyl jasmonate (MJ) on the development of red blush, export‐grade fruit, accumulation of flavonoids in fruit skin and quality of ‘Cripps Pink’ apple were investigated in 2005 and 2006. In the first experiment during 2005, whole trees were sprayed once with 10 mmol L^?1 MJ at weekly intervals from 155 to 183 days after full bloom (DAFB). In second experiment during 2006, different numbers of sprays (0, 1, 2, 3, 4, 5 or 6) of 5 mmol L^?1 MJ were applied from 151 to 179 DAFB. RESULTS: A single spray of MJ (10 mmol L^?1) at 169 DAFB resulted in the highest increase in the red blush, export‐grade fruit, accumulation of anthocyanins, cyanidin 3‐galactosides, chlorogenic acid, phloridzin, flavanols and flavonols in fruit skin as compared to all other treatments without affecting fruit quality. A single spray of 5 mmol L^?1 MJ at 186 DAFB was more effective in improving red blush, export‐grade fruit and accumulation of anthocyanins in fruit skin as compared to its multiple applications. The exposed sides of fruit developed better colour than the shaded sides, regardless of time and numbers of MJ sprays. Time of a single spray of MJ is more effective than its multiple applications. CONCLUSIONS: A single pre‐harvest spray of MJ (10 mmol L^?1) at 169 DAFB or MJ (5 mmol L^?1) at 186 DAFB was effective in improving the red blush and export grade fruit through accumulation of flavonoids in fruit skin without adversely affecting quality at harvest. © 2012 Society of Chemical Industry     

Effects of variety and stage of fruit ripeness on the physicochemical and sensory characteristics of deep‐fat‐fried banana chips

The quality of banana chips prepared from two different varieties of banana, Pisang Abu and Pisang Nangka, at the ‘green’ and ‘trace of yellow’ stages of ripeness was studied. The fruits were peeled, sliced to a thickness of 2 mm and deep‐fat fried in refined, bleached and deodorised (RBD) palm olein at 180 ± 5 °C for 3 min. The quality parameters determined for fresh bananas were total soluble solids, pH, acidity, carbohydrate, sugar content, fat, protein, moisture content, ash, fibre, colour and fruit firmness. The results showed that Abu had a higher carbohydrate content than Nangka at both stages of ripeness before frying. No sucrose was detected in Nangka. The quality parameters determined after deep‐fat frying were moisture content, water activity, oil absorption, crispness and sensory evaluation. The moisture content and water activity of Abu chips were lower than those of Nangka chips. The texture of chips prepared from Abu at stage ‘green’ showed more crispness than the other three samples. Sensory evaluation showed that chips prepared from Abu at both stages of ripeness presented better colour, flavour, odour, texture and overall acceptability than those prepared from Nangka. Based on the matrix of correlation coefficients, fresh bananas with higher fruit firmness and carbohydrate content gave banana chips with higher crispness and oil absorption. © 2001 Society of Chemical Industry     

Impact of ascorbic acid on the oxidative colouration and associated reactions of a model wine solution containing (+)−catechin,caffeic acid and iron

Background and Aims: The aim of this study was to examine the oxidative reactions and associated colouration changes relevant to white wine in a synthetic wine system consisting of different combinations of 200 mg/L caffeic acid, 150 mg/L (+)?catechin and 1000 mg/L ascorbic acid, in the presence of 1.5 mg/L iron(II). Method and Results: Reactions were monitored by UV/VIS, CIELab, LC‐DAD and LC‐MS techniques. When ascorbic acid was less than 90% depleted in samples, it induced yellow/green colouration but prevented brown colouration that would otherwise result from catechin‐ and caffeic acid‐derived yellow and red pigments. However, during the loss of ascorbic acid, in the presence of either catechin and/or caffeic acid, reactions were still occurring to ‘prime’ the system for rapid colour formation. When the ascorbic acid was more than 90% depleted, the samples with catechin and/or caffeic acid had an increased rate of brown colouration compared with those to which ascorbic acid was not added. Conclusions: This study demonstrates that ascorbic acid is an effective anti‐browning agent provided it persists in the wine after bottling, but if depleted, serious brown colouration ensues. Significance of the Study: Findings detailed in this report will provide useful guidelines for the more effective use of ascorbic acid as an anti‐browning agent in bottled wine.     

Colour and phenolic compounds in sweet red wines from Merlot and Tempranillo grapes chamber-dried under controlled conditions

Chamber drying under controlled temperature and humidity conditions of the red grape varieties Merlot and Tempranillo grown in Andalusia (Spain), and the fortification and maceration of the musts in the presence of skin from both types of grapes, to obtain sweet red wines, has been studied. Changes in colour and in monomeric and polymeric phenols during the vinification process were examined. Chamber drying increased the sugar content to about 31.4 °Brix within 48 h in Merlot grapes and 72 h in Tempranillo grapes. This drying process also causes skin rupture, facilitating the access of phenolic compounds to the pulp. The resulting musts exhibited slight browning and increased red hues, due to a high concentration of anthocyanins; maceration in the presence of grape skins for 24 h provided the best results. The end-product contained highly acceptable tannin, colour and phenolic compounds for marketing as a high quality sweet red wine, in comparison with other commercial sweet red wines.     

EFFECT OF COLD STORAGE ON THE QUALITY CHARACTERISTICS OF ‘AU-RUBRUM’ PLUMS1

The effect of cold storage (0°C) and maturity on the physical, chemical and sensory characteristics of plums (cv. ‘AU-Rubrum’) was determined. The size, weight, soluble solids and total sugar contents of the more mature fruit were significantly higher (P<0.05) and the “L” and hue angle were significantly lower (P<0.05) than plums in the less mature class. ‘AU-Rubrum’ fruit contained glucose, fructose and sorbitol but had no sucrose. Artificially ripening fruit at 20°C had a significant effect (P<0.01) on all color values for both maturity 1 and 2 fruit. The titratable acidity and sugar contents of the fruit ripened at 20°C were lower for ripened than for unripened fruit. Storage of the plums at 0°C for 5 weeks followed by subsequent ripening at 20°C had no significant effect on physical, chemical or sensory characteristics. Data indicate that ‘A U-Rubrum’ plums which have one-half red ground color (maturity 1) will develop full color and complete the normal ripening process. Data also indicate that the plums can be stored for at least 5 weeks at O°C without loss of quality and that the cultivar has potential for shipping to distant markets.