綠竹筍採後一般包裝與氣變包裝過程中之組織硬化與相關解剖構造

Abstract

綠竹筍 (Bambusa oldhamii Munro) 為綠竹地下莖節芽所生之幼嫩芽體，主要食用部位為薄壁細胞與維管束組織組成之膨大莖部。本研究係將綠竹筍儲藏於附有孔徑為5 mm之2個孔洞的PE袋中，調查採後組織硬化與相關解剖構造之關聯。一般包裝 (5 mm×2) 並於20℃儲藏之綠竹筍，儲藏期間組織迅速硬化。儲藏5天切面外側、中心與中心往上1.2、2、3.5 cm等部位之硬度各增加113.5%、199.5%、141.2%、82.4%、31.9%。以雙重染色 (Safranin O與Alcian Blue) 及二種木質素染液 (Maule reagent、Wiesner reagent) 分析儲藏期間的組織切片之細胞壁變化，以及分析木質素之存在與分布。分析結果發現，雙重染色之維管束組織之細胞壁染紅面積的增加與硬度增加高度相關，且相關係數為0.93；並且細胞壁染紅有其順序性，依序為早成木質部、近韌皮部之纖維細胞、遠端之纖維細胞，及部分晚成木質部。因此本研究推測組織硬化與維管束厚壁細胞之細胞壁新生物質有關。另一方面，木質素染液之染色結果不明顯，因此關於儲藏期間細胞壁之新生物質是否為木質素，需待更進一步之實驗查證。 本研究另應用氣變包裝 (0.5 mm×2) 與低溫儲藏，以延緩綠竹筍採後硬化。並調查綠竹筍形狀、重量與可食用比例之關係，以及建立一個可由綠竹筍硬度計算儲藏期間可食用體積損耗之系統。氣變包裝與低溫儲藏皆能延緩綠竹筍硬化，但若二種處理同時施用效果更佳。氣變包裝之綠竹筍，儲藏於1℃及10℃皆能有效延緩硬化。實際計算儲藏9天，綠竹筍因硬化造成之可食用體積損耗，1℃之筍幾乎無損耗；10℃之筍可食用體積約減1%。雖然1℃之延緩硬化及保鮮效果較佳，但若僅為短期儲藏，在設備有限並為減少能源消耗之前提下，10℃配合氣變包裝即可有效延緩硬化。

Bamboo shoots (Bambusa oldhamii Munro) are immature, expanding shoots that emerge from nodes of the rhizome in bamboo plants. The major edible part is the swollen stem, which is composed of parenchyma cells and vascular bundles. Bamboo shoots are sealed within perforated (5 mm×2) PE bags, kept in 20℃ to investigate postharvest tissue hardening and related anatomical study. The hardness of outer side of cut surface, central part of cut surface, upward 1.2, 2, 3.5 cm from central part of cut surface increased to 213.5%, 299.5%, 241.2%, 182.4%, 131.9% respectively at the 5th day during the storage in regular packages (5 mm×2). For observing the changes in cell walls and lignin depositions during the storage, the sections of bamboo shoots were histologically stained with dual staining (Safranin O and Alcian Blue), Maule reagent, and Wiesner reagent. The correlation coefficient of hardness and area stained with red was 0.93. The cell walls were stained to the red color in the order of protoxylem, second fibres near phloem, fibres away from phloem, and some of metaxylem. This may indicate that the hardening of bamboo shoots during storage was due to something generated in cell walls. However the lignin test showed that the lignin content was low. But further investigation is needed to define whether those stained with red are lignins or something else. The other part of our research was to retard hardening by atmosphere packages (0.5 mm×2) and low temperature storage. We also investigated the relationships among shape, weight, and volume of edible part of bamboo shoots, and established an evaluative system to measure the lost volume of edible part due to hardening. Both modified atmosphere packaging and low temperature during storage had effects on retarding hardening of bamboo shoots, and it even worked better when applying them both. Bamboo shoots with Modified atmosphere packaging (0.5 mm×2) stored in 1℃ and 10℃ would effectively retard hardening, but those having stored in 1℃ had better quality. However, the lost of edible parts due to hardening was 1% after 9 days storage in 10℃. With consideration of equipments as well as energy conservation, bamboo shoots stored in 10℃ for short time effectively retard hardening.