微化幾丁聚醣在番木瓜保鮮之研究

Abstract

本研究以經過研磨達到微米粒徑大小的幾丁聚醣，對台農二號番木瓜果實及輕度加工果肉進行採後處理，探討幾丁聚醣對木瓜採後品質變化的影響。分別測定果皮、果肉色澤、果實硬度、糖度及表面生菌數，觀察幾丁聚醣對上述影響採後品質因子的影響。在番木瓜果實處理方面，以1%、 0.5%、 0.25% 微化幾丁聚醣(micronized chitosan, MC)與幾丁聚醣(chitosan control, CC)溶液對番木瓜進行浸泡處理，儲藏兩週並測定果實硬度、表皮色澤及果皮表面總生菌數。1% MC處理之果實硬度在儲藏兩週後降低 1.5%， 1% CC處理降低8.9%，兩者與空白組相較具有顯著差異 (P < 0.05) 效果最佳。以hue angle值評估木瓜之表皮顏色，發現MC或CC處理在抑制表皮轉黃上與空白組相較具有顯著效應(P < 0.05)。另一方面，1% MC與1% CC處理組之表皮生菌數於第十日超過104 CFU/g，空白組於第四日則超過此菌數，與處理組有顯著差異。在果肉處理方面，分別以MC及CC對番木瓜輕度加工果肉進行浸泡與噴霧處理，結果顯示1% MC與1% CC以浸泡法處理經五日儲藏後，亮度值與空白組有顯著差異(P < 0.05)，以噴霧方式處理之番木瓜果肉，儲存五天後1% MC與1% CC處理組之亮度與空白組相較具有顯著差異 (P < 0.05)； 1% MC處理失重率為4.36%，1% CC處理為5.62%，1% MC處理與空白組(6.66%)相較有顯著差異(P < 0.05)。1% MC與1% CC處理組之果肉表皮生菌數於第四日超過104 CFU/g，空白組於第二日超過此菌數，與處理組有顯著差異。此外番木瓜果肉經由浸泡方式處理，在儲藏兩日後開始會產生水傷現象，而噴霧方式處理可避免水傷產生。

The objective of this study was to evaluate the postharvest applicability of micronized chitosan on fruit and freshly-cutted sliced papaya (Tainung No.2). Two kinds of chitosan, micronized chitosan (MC) and chitosan control (CC), were used in this study. Color of fruit surface and flesh, fruit hardness, soluble solid, and microorganisms were assayed to evaluate the effects of micronized chitosan on the postharvest quality factors. Our results showed that fruit hardness with 1% (w/v) CC treatment was decreased by 1.5% after 2 weeks storage, and that with 1% MC treatment was decreased by 8.9%, the hardness with both two treatments were significant (P < 0.05) higher than that with the control treatment. Fruit color were evaluated by hue angle value. MC and CC treatments effectively (P < 0.05) inhibited the yellowing of fruits surface. The colony forming unit (CFU) of 1% MC and 1% CC treatments was over 104 CFU/g at the 10th day of storage, but that of the control was over 104 CFU/g at the 4th day. A significantly (P < 0.05) difference in CFU among different treatments was observed. MC and CC have been used to treat freshly-cutted papaya by soaking and spraying methods. Soaking treatments using 1% MC and 1% CC resulted in a significant (P < 0.05) change in flesh bright value as compared to the control. A similar phenomenon was observed in the spraying treatments using 1% MC and 1% CC. In weight-lose observation, 1% MC, 1% CC, and control treatments resulted in weight reduction by 4.36%, 5.62%, and 6.66%, respectively as compared with, showing that 1% MC treatment showed a significant (P < 0.05) difference to the control. The CFU with 1% MC and 1% CC treatments was over 104 CFU/g at the 4th day of storage, and that of the control was over 104 CFU/g at the second day, suggesting that MC and CC treatments resulted in a significant reduction in the growth of microorganisms. Soaking treatment caused water core injury after two days of storage, while spraying method could avoid this problem.