STORAGE CHARACTERISTICS OF 'FUYU' PERSIMMONS

Non-astringent persimmons {Diospyros kaki cv. Fuyu), grown in Gainesville, Florida, were harvested on 2 Nov. and 9 Nov. 1992. Fruit were firm and uniformly yellow at harvest. Fruit were stored at 32, 41, 50, or 68F (0, 5, 10, or 20C) for two weeks, followed by one week at 68F (20C). After storage, nearly all fruit originally at 41F (5C) showed chilling injury and were unmarketable. These developed a yellow-brown color and water-soaked appearance, and were very soft. Those persimmons from the first harvest, which were initially stored at 32, 50, or 68F (0, 10, or 20C), developed good color after 1 week at 68F (20C), and most were market able. Of fruit harvested on 9 Nov. those stored at 32 or 68F (0 or 20C) were marketable, while 80% of the 41F (5C) and 60% of the 50F (10C) treatment fruit were not. There were no significant differences between pH or soluble solids of the pulp among storage treatments, and no decay developed during storage. Based on these results, recommended storage tem peratures for Florida-grown 'Fuyu' persimmons are 68F (20C) if rapid ripening is desired, or 32F (0 C) for longer storage. The oriental persimmon, Diospyros kaki L. , has been grown in Florida for many years. In the early 1900s there were commercial plantings of astringent Kaki persimmons numbering about 22,750 trees (Miller and Crocker, 1992). This industry did not successfully establish because of mar keting difficulties. Plantings of non-astringent Kaki per simmons are increasing in the U.S. with about 600 ha now in production. California leads in production with a return to grower between $. 28 and 1.12 per kg of fruit (Collins et al., 1993). With more acreage being planted to persimProc. Fla. State Hort. Soc. 106: 1993. 131 mon in Florida there has been increased interest in extend ing the shelf-life of persimmons to extend the market. Non-astringent Kaki persimmons grown in Japan can be stored for 3 mo at OC, but in New Zealand cold injury occurred at (4C), and storage life was reduced to 4 weeks (MacRae, 1987). Therefore it was decided that locally grown persimmons should be evaluated at various temper atures and times for the best storage conditions. Materials and Methods Non-astringent 'Fuyu' persimmon grown in Gainesville, Florida, were harvested on 2 Nov. and 9 Nov. 1992. Fruit were selected for uniformity of size and color, with those having even yellow coloration of 3.5 to 4 on the color scale developed in Japan for 'Fuyu' (Yamazeki et al., 1981). Pre liminary studies in 1989 (unpublished data, Sargent) re vealed the variability in ripening at other color stages. For this reason, all fruit were harvested at the yellow color stage. The fruit had not begun to soften at harvest. Fruit were stored in styrofoam trays covered with plastic bags left slightly open at one end to maintain a high relative humidity while allowing some air movement. Fruit were stored at either 32, 41, 50, or 68F (0, 5, 10, or 20C) for 2 weeks and at 68F (20C) for 1 week to simulate retail market conditions. There were 36 fruit per storage temperature from the first harvest and 40 fruit per storage temperature from the second harvest. The persimmons were checked periodically during storage for softening or decay. Fruit were removed from storage when soft over two-thirds of the surface, the point considered to be too soft for com mercial shipping. After the 7 days of storage at 68F (20C), five firm and five soft fruit of those remaining in each treatment were evaluated for color using the color scale developed in Japan for 'Fuyu' persimmons (Yamazeki et al., 1981), and rated for surface blemishes, decay, and marketability. Firmness was measured using an IFAS Firmness Tester, which con sisted of a 0.59 in. (15 mm) convex probe placed on the fruit surface to which a static load of 2.205 lb-f (9.8 N) was applied for five sec, at which time deformation in 0.01 inch (0.25 mm) increments was measured. Three non-de structive deformations were made around the equator of each intact fruit. Fruits were selected for analysis based on similarity of firmness measurements (0.02-0.05 inches, 0.51-1.27 mm, for firm fruit and 0.13-0.25 inches, 3.306.35 mm, deformation for soft fruit) and similarity of color. After the storage period plus one week at 68F (20C), seeds and peel were removed from five soft and five firm fruits for each treatment, and fruit pulp was analyzed for pH and soluble solids using a Corning model 140 pH meter and Abbe Mark II digital refractometer. Results and Discussion Storage of 'Fuyu' fruit from the first harvest for 2 weeks at 32, 50, or 68F (0, 10, or 20C) followed by 1 week at 68F (20C) resulted in good quality, marketable fruit (Table 1). From the second harvest (Table 1), those fruit stored initially at 32F (0C) or 68F (20C) were marketable, while 60% of the fruit stored initially at 50F (10C) were not marketable due to symptoms of chilling injury. Fruit considered mar ketable showed satisfactory color development and normal flesh appearance, with a good aroma and flavor. They were still firm when at the orange color stage, which is a desirable characteristic because the non-astringent 'Fuyu' is normally eaten crisp, as are apples. Those fruit initially stored at 41F (5C), and some of those stored at 50F (10C), (Table 1) showed marked symptoms of chilling injury, in cluding poor color development (a brownish-yellow), rapid softening, and a dark, water-soaked surface appearance. The pulp was unattractive and did not develop an accept able aroma. Marketability was evaluated subjectively as marketable or unmarketable, with those fruit with water-soaking, an unattractive color, or more than moderate blemishes being considered unmarketable. From the first harvest, only those fruit stored at 41F (5C) were unmarketable after one week at 68F (20C) (Table 1). For the second harvest, all of the 4 IF (5C) -stored fruit and 60% of the 50F (10C) -stored fruit were unmarketable, primarily due to chilling injury. If the fruit had been observed for more than a 2-week period, the 50F (10C) fruit from the first harvest may have developed chilling symptoms. Table 1. Storage temperature effects on quality of 'Fuyu1 persimmons harvested on 2 Nov. Two week Storage Temp. (°C)Z Firmness at 3 weeks Deformation (Firmness) (inchesy) Color Stage* Surface Blemish RatingTM Marketable 0 0 5 5 10 10 20 20 Firm Soft Firm Soft Firm Soft Firm Soft 0.027 (0.010)v 0.252 (0.099) 0.178(0.053) 0.030 (0.006) 0.137(0.028) 0.039 (0.006) 0.150(0.061) 5.5 (0.447)v 6.0(0.316) 6.3 (0.600) 6.0 (0.894) 5.9 (0.583) 5.8(0.510) 7.0 (0.632) 2.8 (0.980)v 3.2 (0.748) 3.6(0.490) 2.4 (0.800) 3.4 (0.490) 2.4 (0.490) 2.6 (0.800) 100 80.0