Preparation of microcrystalline cellulose from by-products of wheat seedling juice and its applications

Abstract

The objective of this study is to evaluate the feasibility of producing microcrystalline cellulose (MCC) from the waste during wheat (Triticum aestivum L.) seedling juice processing by using different concentration of alkaline, acid treatments and drying methods and then measure the physicochemical properties of wheat seedling pomace MCC powders as well as the effects on the texture of jelly products. The results showed that the amount of crude fiber was 39 % and α-cellulose content through purification procedure was 72-77 %, so it was adequate to produce wheat seedling pomace MCC. By the manufacturing procedure of this study, either the X-ray diffraction angle or FTIR spectrum of wheat seedling pomace MCC were almost the same as the commercial one so that it represented that the method of this study was available to produce MCC. When using 17.5 %NaOH, it would cause transformation from cellulose Ⅰto cellulose Ⅱ, besides, 17.5 %NaOH-treated samples (cellulose Ⅱ) had higher crystallinity index by XRD and FTIR, and it also had properties of high heat stable abilities, bulk desities and etc,. The DP of 17.5 %NaOH-treated samples (cellulose Ⅰ) was close to the commercial one and its freeze-dried samples could maintain better long rod shape on SEM graph. According to different acid treatments, HCl-treated samples had better CrI, higher heat degradation temperature, and bulk and tapping densities than H2SO4-treated samples. On the aspect of different drying methods, vacuum-dried samples were spherical-like because of the folding of rod fibers, and the 1.5 % NaOH-treated following freeze-dried samples had two to four folds of WRC compared with the other ones. Furthermore, when applying to the jelly products for texture analysis, almost all the hardness, gumminess, springiness, cohesiveness, chewiness and resilience of wheat seedling MCC jelly were higher than the commercial one. At last, according to the result of sensory evaluation, almost all of the samples were better than the commercial one on all the parameters, but there were no differences between them. In summary, we could know that producing wheat seedling MCC was available, and in addition to improve the quality of food, it could achieve the goal of utilization of agricultural wastes as well.

本研究擬探討利用不同鹼濃度、酸處理及乾燥方法製備小麥草渣微晶纖維素之可行性，並探討小麥草微晶纖維素物化特性及添加於果凍中對其質地之影響。結果發現，小麥草渣之粗纖維含量約占39 %，且經純化處理可得約72-77 %之α-纖維素含量，可用來製作小麥草渣微晶纖維素。利用本實驗的微晶纖維素製作方法，不管在X-ray繞射角度或FTIR圖譜上皆和市售樣品極為相似，顯示以本實驗之方法製備微晶纖維素之可行性。使用17.5 %NaOH可有效使cellulose Ⅰ轉換到cellulose Ⅱ，另外也使17.5 %NaOH處理樣品 (cellulose Ⅱ)在X-ray及FTIR上都有較高的結晶度產生，而其也具有熱穩定性高、體積密度高等特性。1.5 %NaOH處理樣品 (cellulose Ⅰ)的聚合度與市售樣品較相近類似，而其冷凍乾燥樣品在SEM上可維持較好的纖維長條形狀。在不同酸處理方面，鹽酸處理樣品比起硫酸樣品具有較好結晶度、高熱裂解溫度、高體積和振實密度。在不同乾燥方法，真空乾燥樣品多呈因棒狀纖維堆疊的球狀，而冷凍乾燥在1.5 %NaOH處理下，保水力是其他組的2-4倍。從果凍上應用來看，幾乎所有小麥草渣MCC果凍於質地分析之硬度、膠性、彈性、黏聚性、咀嚼度跟回復性都要比市售質地來得高。最後由感官品評結果發現，添加市售和小麥草渣微晶纖維素之果凍樣品於混濁度、硬度、Q度及整體接受度皆優於未添加微晶纖維素之果凍樣品，不過各樣品間較無顯著差異。因此，綜合上述，可知利用搾汁剩餘的小麥草渣製作微晶纖維素是可行的，除了可達到改善食品品質外，也達到農業廢棄物回收利用的目的。