過熱蒸氣於烤藷之開發與應用

The exploitation and application of roasting sweet potatoes by superheated steam

翁振展(Jhen-Jhan Wong)

指導教授 ： 楊季清

國立屏東科技大學/農學院/食品科學系所/碩士(2008年)

https://doi.org/10.6346/NPUST.2008.00026

摘要

甘藷在一般加工製程中，以烤的方式最受消費者所喜愛，因為在烤焙的過程中會發生梅納反應，使烤藷散發出誘人的香氣，但由於烤焙時間長，易使甘藷外觀發生焦黑的情形，故本研究利用過熱蒸氣熱傳快的優點改善此問題，並開發出綠茶口味的甘藷以增加在市場上的競爭力。研究結果顯示，100~150 g大小的甘藷分別經過熱蒸氣和烤在30 min處理下，發現過熱蒸氣以140℃就可使甘藷熟，而烤必需在240℃。在外觀上，甘藷經過熱蒸氣處理不會造成焦黑的情形，而以烤焙者則會發生。甘藷經過熱蒸氣140℃下30 min處理，經感官品評和質地剖面分析後，其兩者的結果相近，但在香味上則以烤處理後的甘藷較高。在抗氧化力方面，發現總酚、清除DPPH (1,1-diphenyl-2-picrylhydrazyl) 自由基能力、FRAP (Ferric Reducing Ability of Plasma) 皆以過熱蒸氣高，但在類黃酮含量上則兩者相近。200~250 g其結果與100~150 g的甘藷相近，甘藷以過熱蒸氣取代烘烤的方式是具有可行性的。
在開發綠茶甘藷的實驗中，隨著浸泡時間的增加，在總酚、清除DPPH自由基能力、FRAP方面，都會有顯著提高的現象，但在類黃酮方面其上升的量並不多。此外，甘藷浸於無糖綠3 hr後，其抗氧化能力為最高，但在感官品評上由於其澀味重，並不被消費者接受；然而以甘藷浸於30 °Brix的綠茶3 hr者最被大眾所接受。

關鍵字

過熱蒸氣 ； 烤藷 ； 抗氧化力

並列摘要

Among common processing methods of sweet potatoes, roasted ones are the most favorite for general consumers, since it would yield maillard reaction in roasting process and produce attractive aroma, but the long duration of roasting would also easily make sweet potatoes burnt black. Therefore, the study would use the advantage of superheated steam’s swift heat-conduction to improve this problem and develop roasted sweet potatoes with green tea flavor so as to increase the competitive potential in markets. As the research results showed, when sweet potatoes of 100~150 grams were respectively roasted by superheated steam and broil for 30 minutes, it found that the sweet potatoes could be cooked by 140℃ superheated steam, while roasting needs to use the temperature as high as 240℃. In appearance, the sweet potatoes processed by superheated steam would not become burnt black as the roasting process would do. After processed by 140℃ superheated steam for 30 minutes, the sensory evaluation and profile analysis of quality between these two groups were similar, but the aroma of roasted sweet potatoes was higher. As to anti-oxidant capability, it found the total phenol, elimination of DPPH (1, 1-diphenyl-2-picrylhydrazyl) free radicals, FRAP (Ferric Reducing Ability of Plasma) among those sweet potatoes processed by superheated steam were higher, but the quantity of flavonoids between those two groups were similar. And the results between both 200~250 g and 100~150 g sweet potatoes were also similar, which proved it was feasible to substitute superheated steam process for roasting.
In the experiment of developing sweet potatoes with green tea flavor, the total phenol, elimination of DPPH (1, 1-diphenyl-2-picrylhydrazyl) free radicals, FRAP (Ferric Reducing Ability of Plasma) have been significantly higher as the duration of soaking lengthened. But the quantity of flavonoids didn’t increase much. Besides, after soaked in sugar free green tea for 3 hours, the anti-oxidant capability was promoted to top, but due to the heavy astringency in the sensory evaluation, it couldn’t be accepted by the consumers; the sweet potatoes soaked in 30°Brix green tea for 3 hours can be accepted by the consumers.

並列關鍵字

Superheated steam ； roasted sweet potato ； anti-oxidant capability

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