Symptoms of external chilling injury, primarily brown-staining of the rind, of watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] were reduced by conditioning fruit at 26°C for 4 days before storage at 0° or 7°. No loss of marketable fruit occurred in nonconditioned melons stored at 0° for 4 days, or in conditioned melons stored at 0° for 12 days. Further lengths of 0° storage resulted in chilling injury and increased loss of marketable fruit. The amount of brown-staining intensified during 4- and 8-day holding periods at 21° after removal from storage at 0° for 8 days or longer, but was always less in conditioned fruit. Less chilling injury occurred in fruit stored at 7° than at 0°. No loss of marketable fruit occurred in conditioned melons stored for 8 days at 7° followed by holding at 21° for up to 8 days. A slight fruit loss occurred in nonconditioned melons subjected to the same treatment. ‘Charleston Gray’ was slightly more susceptible to chilling injury than ‘Crimson Sweet’ or ‘Jubilee’, among nonconditioned fruit.
Sugar and organic acid concentrations in fruit of two cherry tomato (Lycopersicon esculentum var. cerasiforme Alef.) cultivars (‘Large Red Cherry’ and ‘Small Fry’) were determined at five stages of ripening. Fructose and glucose concentration increased in both cultivars from the immature-green to table-ripe stage, with fructose being the primary sugar. Sucrose, present in low concentration, was higher in the immature-green than table-ripe stage. Citric acid was the primary organic acid and it increased in concentration from the immature-green to mature-green stage (and to the light-red stage in ‘Small Fry’), but no further change occurred from the light-red to table-ripe stage. Malic acid decreased in concentration from the mature-green to table-ripe stage. ‘Large Red Cherry’ fruit contained more fructose, glucose, and malic acid, but less citric acid than ‘Small Fry’ fruit. The pattern of sugar and organic acid change during cherry tomato fruit ripening was similar to the pattern of change previously reported for large-fruited types.
The quantity and pattern of carbohydrate change during curing and storage differed among 6 sweet potato [Ipomoea batatas (L.) Lam] cultivars. ‘Travis’ contained the most total sugar and ‘Whitestar’ the least on a dry weight basis. Sucrose, the major sugar in raw sweet potatoes, sharply increased during curing (10 days at 32°C; 90% RH), and generally continued to increase in 4 orange-flesh cultivars during 46 weeks of 15.6° storage. Sucrose concentration decreased in 2 white-flesh cultivars after curing, followed by an increase after 14 weeks of storage. Glucose concentration was slightly higher than fructose in all cultivars except ‘Centennial’, which had similar monosaccharide concentrations. The pattern of monosaccharide change during curing and storage varied with cultivar, but generally increased during curing and the first 4 weeks of storage, followed by stabilization or a slight increase. Alcohol-insoluble solids (AIS) decreased with increasing lengths of storage in the 4 orange-flesh cultivars, which was attributed to continuous starch degradation. AIS increased during the first 4 or 14 weeks of storage in the 2 white-flesh cultivars, followed by a decrease during longer periods of storage.
Yellow shoulder (YS) expression was associated with differences in composition, respiration rate, and ethylene evolution between the yellow and normal red tissue in tomato (Lycopersicon esculentum Mill.) fruit. The YS tissue was higher in pH, dry matter, alcohol-insoluble solids (AIS), calcium content, respiration rate, and ethylene evolution than the red blossom-end tissue. The YS tissue had less phosphorus, potassium, citric acid, and a lower titratable acidity than the red tissue. Expression of YS was not associated with imbalances in fructose, glucose, malic acid, nitrogen, or magnesium concentration. Substantial YS development occurred in fruit of nonuniform ripening gene cultivars allowed to vine-ripen. Yellow shoulder was alleviated by harvesting fruit in the mature-green stage and room-ripening.
External chilling injury symptoms, primarily surface pitting followed by secondary fungal decay, developed in six sweet potato [Ipomoea batatas (L.) Lam] cultivars after an exposure to 7°C for 2 weeks or more followed by storage at 15.6°. Internal chilling injury symptoms, primarily darkening of the cambium and vascular bundles, were observed in noncured ‘Whitestar’ and ‘Rojo Blanco’ roots after exposure to 7° for 3 weeks and in ‘Centennial’ after exposure to 7° for 4 weeks followed by storage at 15.6°. ‘Jewel’ was the cultivar most tolerant to low temperature. Chilling injury and respiration rate were greater with increasing lengths of exposure to 7° and were greater in noncured than cured roots. Enhanced sucrose and total soluble sugar content occurred at 7° compared to 15.6°. The primary sugar responsible for low-temperature sweetening was sucrose, but there was considerable variation among cultivars in the extent of low-temperature sweetening and specific sugar changes.
In the article “Weight Loss in Sweet Potatoes During Curing and Storage: Contribution of Transpiration and Respiration”, by David H. Picha (J. Amer. Soc. Hort. Sci. 111:889–892, November 1986), Figs. 1 and 2 were reversed. The correct figures and captions are printed below.
Fruit of 2 cherry tomato (Lycopersicon esculentum var. cerasiforme Alef.) cultivars [‘Large Red Cherry’ (‘LRC’) and ‘Small Fry’ (‘SF’)] and 2 large-fruited tomato (Lycopersicon esculentum Mill.) cultivars (‘Duke’ and ‘Sunny’) were harvested green, ripened at 23°C, and analyzed for sugars and organic acids 6 days after breaker stage. Both fructose and glucose concentration decreased in ‘LRC’ and ‘SF’ fruit with less-mature harvested fruit. Maturity at harvest had no effect on the concentration of either sugar in ‘Duke’ or ‘Sunny’ fruit. ‘LRC’ had the highest fructose and glucose concentration among cultivars. Increased citric acid concentration was found with less-mature harvested fruit, except in ‘LRC’. Malic acid concentration within cultivars was similar in the fruit harvested more mature, but decreased with less-mature fruit in ‘Duke’ and ‘Sunny’. ‘LRC’ and ‘SF’ fruit had more citric and malic acid than ‘Duke’ or ‘Sunny’. Cherry tomato cultivars had a higher percentage of locular tissue than the large-fruited cultivars.
Cured sweet potatoes [Ipomoea batatas (L.) Lam] were stored successfully at 15.6°C and 90% RH for up to a year without sprouting. Contribution of respiration and transpiration to total weight loss was determined during curing and storage in 6 cultivars. Respiration rate was highest the day of harvest, decreased during curing, and continued to decrease at a slower rate during the first several months of storage, whereafter it remained constant (except for slight increases during the last several months in 2 cultivars). Respiration contributed more to total weight loss during the latter periods of storage than during curing or the first months in storage. Transpiration, however, was the major source of weight loss. The highest rate of weight loss occurred during curing, followed by a gradual rate of loss during storage. Total weight loss of cured roots after 50 weeks of storage ranged from 6.7% (‘Rojo Blanco’) to 16.1% (‘Travis’).
Sweetpotato is considered a good source of ascorbic acid (vitamin C) and certain B vitamins. These water-soluble vitamins (WSV) play essential roles in sustaining human health. Besides the root, sweetpotato vegetative tissues are also edible and considered high in nutritional value. Despite the availability of general reference values for sweetpotato WSV content in the root and leaves, little is known about the distribution of these vitamins in specific sweetpotato root and vegetative tissues. The objective of this study was to determine the ascorbic acid (AA), thiamin (B1), riboflavin (B2), and vitamin B6 content in a range of foliar tissues including buds, vines, young petioles, young leaves, mature petioles, and mature leaves and root tissues including the skin, cortex, and pith tissue at the proximal, distal, and center regions of the root. Among foliar tissues of ‘Beauregard’ sweetpotatoes, the AA content was highest in young leaves (108 to 139 mg/100 g fresh weight) and lowest in mature petioles (7.2 to 13.9 mg). No thiamin was detected in foliar tissue, whereas mature leaves contained the highest riboflavin and vitamin B6 content (0.22 to 0.43 mg and 0.52 to 0.58 mg, respectively). In root tissues of ‘Beauregard’ and ‘LA 07-146’ sweetpotatoes, the AA content was lower in the skin (1.9 to 5.6 mg and 2.54 to 3.82 mg, respectively). The AA content in the cortex and pith tissue at the proximal, distal, and center of the root was generally similar. The thiamin content was variable among root tissues, whereas the skin contained the highest riboflavin content and the lowest vitamin B6 content across root tissues of both cultivars. The results of this study confirmed earlier reports suggesting that sweetpotato leaves can be a good source of multiple WSV in the human diet.
Phenolic compounds and antioxidant activity were quantified in the principal sweetpotato cultivars marketed in the European Union. Total phenolic content, individual phenolic acids, and antioxidant activity in each cultivar were determined using Folin-Denis reagent, reversed-phase HPLC, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods, respectively. Significant differences in phenolic composition and antioxidant activity were found between cultivars. A Jamaican-grown, white-fleshed cultivar had the highest total phenolic content [4.11 mg·g-1 chlorogenic acid (dry tissue weight)], while the highest antioxidant activity [3.60 mg·g-1 Trolox (dry tissue weight)] was observed in the orange-fleshed California-grown cultivar Diane. Chlorogenic acid and 3,5-dicaffeoylquinic acid were the predominant phenolic acids, while caffeic acid was the least abundant in most cultivars. The highest content of chlorogenic acid (0.42 mg·g-1 dry tissue weight); 3,5-dicaffeoylquinic acid (0.43 mg·g-1 dry tissue weight); and 3,4-dicaffeoylquinic acid (0.25 mg·g-1 dry tissue weight) was present in the white-fleshed Jamaican cultivar. The orange-fleshed cultivars Diane and Beauregard had the highest content of caffeic acid (0.13 mg·g-1 dry tissue weight) and 4,5-dicaffeoylquinic acid (0.32 mg·g-1 dry tissue weight), respectively.