Studies on the Changes of Chemical Components of Dried Jujube (Zizyphus jujuba MILLER) during Storage

대추 (Zizyphus jujuba MILLER)의 저장중(貯藏中) 화학성분변화(化學成分變化)에 관(關)한 연구(硏究)

In order to find out changes of chemical components related to browning of dried jujube, four varieties were subjected to the proximate analysis. Boeun, one of the major varieties in Korea, was sun-dried and stored for 12 months and analyzed periodically for one year. Browning, titrable acidity, pH, contents of ascorbic acid, organic acid, total amino acid, free amino acid, free sugar, hydroxymethylfurfural (HMF) and phenolic compounds were determined and compared with those of fresh jujube. The results obtained are summarized as follows; 1. In comparison with other similar fruits, jujube was high contents of ascorbic acid (62-79mg%) and carbohydrate (22-28%) excluding fiber. 2. Browning was increased in both steam-treated and nontreated plot together as storage period was prolonged. 3. Ascorbic acid content of fresh jujube was as high as 297.4mg% DB, but it was decreased to 20.2mg% DB, after 12 months storage. Therefore, loss of ascorbic acid was very great up to 93% of its original content. 4. Five kinds of organic acid, oxalic, succinic, fumaric, malic and citric acid were identified as major organic acids. It was interesting that only fumaric acid content was increased while others decreased during storage. 5. Seventeen kinds of amino acid were identified in the analysis of total amino acid content. Major amino acids were found to be proline, threonine, glutamic acid and lysine. During 12 months storage, 30% of original total amino acid was decreased and this was mostly accounted for free amino acids. 6. Threonine, proline, alanine and valine were identified as free amino acids which showed 85% decrease after 12 months storage. 7. Free sugars of jujube were composed of fructose, glucose and sucrose. They showed 24% decrease after 12 months storage, Especially sucrose was not detected after 4 months storage. 8. HMF of dried jujube was isolated and identified. Its content was increased up to great extent as storage period prolonged. 9. Caffeic, ferulic and P-coumaric acid were identified as jujube phenolic compounds which were significantly decreased during storage. In conclusion, non-enzymatic browning was thought to be more important than enzymatic reaction in the dried jujube. Amino-carbonyl reaction, ascorbic acid oxidation and reaction between phenolic compounds and sugar or nitrogen compounds were observed to be related to this browning.

건조(乾操)대추의 저장기간중(貯藏期間中)에 나타나는 갈변현성(褐變現象)과 화학성분(化學成分)의 변화(變化)를 검토(檢討)하기 위하여 4품종(品種)의 신선(新鮮)한 대추를 수집(蒐集)하여 일반화학성분(一般化學成分)을 분석(分析)하여 품종간(品種間)의 성분함량(成分含量)을 비교(比較)하고 이들중 보은(報恩)대추를 천일(天日) 건조(乾燥)하여 상온(常溫)에서 12개월(個月)동안 저장(貯藏)하면서 경시적(經時的)으로 색상(色相), 적정산도(滴定酸度), pH, vitamin C, 유기산(有機酸) 총(總) amino산(酸), 유리(遊離) amin산(酸), 유리당(遊離糖), hydroxymethyl furfural (HMF) 및 phenol 화합물(化合物)들을 분리정량(分離定量)하여 다음과 같은 결과(結果)를 얻었다. 1. 신선(新鮮)한 대추의 일반화학성분중(一般化學成分中) 수분(水分) 외(外)에는 당질(糖質)(22-28g)과 vitamin C(62-72mg)의 함량(含量)이 많았으며 품종간(品種間)에는 큰 차이(差異)가 나타나지 않았다. 2. 건조(乾操)대추의 갈색도(褐變度)는 저장기간(貯藏期間)에 따라 증자처리구(蒸煮處理區) 비처리구(非處理區) 모두 크게 증가(增加)되었다. 3. 신선(新鮮)한 대추의 vitamin C 함량(含量)은 297.4mg%DB이었으나 건조(乾操)한 후(後) 12개월(個月) 저장(貯藏)하였을 때는 20.2mg%DB로 약(約) 93%가 소실(消失)되었다. 4. 유기산(有機酸)은 oxalic acid, succinic acid, fumaric acid, malic acid, citric acid의 5종(種)이 동정(同定)되었고 저장중(貯藏中)의 함량변화(含量變化)는 fumaric acid만이 증가(增加)되었고 나머지 4종(種)의 유기산(有機酸)은 감소(減少)하였다. 5. 총(總) amino산(酸)은 17종(種)이 동정(同定)되었고 이들중(中) 주요(主要) amino산(酸)은 proline, threonine, glutamic acid, lysine이었으며 저장기간중(貯藏期間中) 총(總)aminol산(酸)은 약(約) 30% 감소(減少)되었다. 6. 유리(遊離) amino산(酸)은 threonine, proline, alanine, valine의 4종(種)이 동정(同定)되었으며 proline의 함량(含量)이 특(特)히 많았고 저장기간(貯藏期間中)중 평균(平均) 85%가 감소(減少)하였다. 7. 건조(乾操)대추의 유리당(遊離糖)은 fructose, glucose, sucrose로 구성(構成)되었 으며 12개월(個月) 저장(貯藏)하였을 때 유리당(遊離糖)의 총(總) 함량(含量)이 24% 감소(減少)하였으며 sucrose는 4개월(個月) 이후(以後)에는 검출(檢出)되지 않았다. 8. 저장중(貯藏中)의 대추에서 HMF를 분리동정(分離同定)하였으며 저장기간(財藏期間)에 따라 그 함량(含量)은 현저(顯著)하게 증가(增加)하였다. 9. 건조(乾燥)대추의 phenol 화합물(化合物)로는 caffeic acid, ferulic acid, P-coumaric acid의 3종(種)이 동정(同定)되었고 그 함량(含量)은 저장기간중(貯藏期間中)에 상당(相當)한 양(量)이 감소(減少)되었다.