甜柿果實澀味之變化及影響因子

Fluctuation of Astrigency and Related Affecting Factors in 'Fuyu' Persimmon Fruits

林慧玲(Huey-Ling Lin) ； 阮雅蘭(Ya-Lan Ruan)

《臺中區農業改良場特刊》 71號 (2004/12) Pp. 185-193

https://doi.org/10.29563/ZHWHGX.200412.0012

摘要

甜柿栽培面積2723公頃，主要以台中縣和平鄉栽培最多，種植面積達1500公頃，年產量約2萬多公噸，主要栽培甜柿品種以富有及次郎為主。而甜柿與澀柿品系之主要差異，在於是否可在樹上完成脫澀。柿果澀味之產生主要與可溶性單寧濃度有關，澀柿品系果實成熟時其可溶性單寧可高達2%且幼果至成熟果均維持4〜2%之濃度，但以中果期單果累積量較高可達3g之多，而富有甜柿從幼果至果實成熟期，可溶性單寧由2%下降至0.05%以下，而單果累積量則幼果至成熟果並無明顯之差異均維持在0.3〜0.15g間，因此，甜柿在幼果期單寧濃度較高具澀味，隨果實之發育及增大產生稀釋效應，而使可溶性單寧下降至0.2%以下，此時口中味蕾與可溶性單寧無法形成鞣化作用而不會感覺澀味之存在，因此不需經過脫澀處理可直接鮮食。但可溶性單寧之聚合反應與溫度有關，一般澀柿脫澀最適溫度為30〜35℃，可快速去澀，溫度愈低脫澀速率愈慢。本實驗室於民國92年調查不同海拔高度之甜柿品質及可溶性單寧，產區包括東勢、摩天嶺、隙頂、石桌及梨山等地區，結果顯示，海拔較高之果實，可溶性單寧較高，以梨山地區可溶性單寧較高，其次為隙頂及石桌；果實品質以梨山地區較佳，果色橙紅亮度高，採收期可延至12月〜1月份。海拔高度愈高，可溶性單寧含量較高之主要原因為氣溫較低而影響果實之生長速率，高海拔生長速率較慢，對幼果期累積之可溶性單寧之稀釋效應較小，因此，高海拔地區之甜柿果實殘留澀味之原因可能為氣溫過低影響單寧之聚合或單寧之稀釋效應較低所致。

關鍵字

可溶性單寧 ； 澀味 ； 果實發育

並列摘要

The cultivating areas of persimmon in Taiwan are currently 2723 ha. The main sites of production are in Ho-Peing Village in Taichung county with a cultivation land of about 1500 ha and an annul yield of 2 million tons. 'Fuyu' and 'Jiro' are the two major cultivars.The distinction between non-astringency and astringency cultivars are based on whether the fruits could complete the process of deastringency before harvesting. The astringency of fruits was closely related to the soluble tannin content. Astringent cultivar, 'Bull Heart', contained as high as 2% soluble tannin while fruit was ripe and a fluctuation of the compound within 2~4% ranges during the period of growth and development. The soluble tannin per fruit could reach 3 g in the mid-phase of fruit growth. In contrast with the non-astringent 'Fuyu' cultivar, the soluble tannin decreased from 2% in young fruits to 0.05% while fruits reached maturity. The accumulation of soluble tannin per fruit was maintained at 0.3 to 0.15 g all through the growth period. Therefore, 'Fuyu' persimmon had a relatively high soluble tannin concentration in young fruits and thus with the bitter taste, which decreased (to 0.2 %) as time went by due to the dilution effect of fruit growth. Consequently, no deastringency was necessary before eating fresh. The precipitation of soluble tannin in fruit cells was related to the ambient temperature. The most suitable temperatures for deastringency of the persimmon were 30 to 35 C, and the process slowed down as temperature droped. In 2003, investigations of fruit quality and soluble tannin content of 'Fuyu' were conducted at different altitudes including Don-Tsi, Mo-Tai-Len, Sei-Dou, and Le-Sun areas. Results indicated that soluble tannin concentrations were higher at elevated locations such as Le-Sun. The Se-Dening and Sei-Dou grown persimmons were next in order. Fruit's quality was best at Le-Sun where the bright orange-red fruits were collected and harvesting season could be extended to December or next January. The reasons for high fruit's soluble tannin are owing to the low temperature that decreases the fruit growth rate and thus less dilution effect or precipitation of soluble tannin, which were responsible for the stronger astringency remaining in persimmons harvested at a high altitude.

並列關鍵字

soluble tannin ； astringency ； fruit development