香蕉抗性淀粉研究进展

Research Progress of Banana Resistant Starch

抗性淀粉(Resistant starch,RS)是指在120 min内不能被健康人体小肠消化和吸收、但在大肠中能够被发酵的淀粉及其淀粉降解物的总称,具有预防糖尿病、改善肠道微环境、降血糖、降血脂和减肥等多种保健作用,引起农业、食品和医药等领域学者的极大兴趣,已成为作物营养品质改良、健康食品研发的热点内容之一。依据其化学结构、来源和性质不同,RS共分为RS_(1)、RS_(2)、RS_(3)、RS_(4)和RS_(5)等5种类型。香蕉是世界贸易量最大水果和世界第四大粮食作物,为全球20亿人口碳水化合物来源。香蕉RS属于RS_(2)类型,是唯一被美国食品和药物管理局确定为膳食纤维的RS。青香蕉果实富含RS(>40%),远高于水稻(<3%)、小麦(<3.5%)和高直链淀粉玉米(<22.4%)等作物,是功能性食物的直接来源。自1982年英国生理学家Englyst首次发现并命名RS以来,香蕉在RS颗粒形态特征、加工处理条件与络合反应对RS颗粒形态特征变化影响、积累和降解特点与果实品质形成关系、制备方法及食品加工中的应用等方面均取得了较大进展。但与水稻等作物相比,在涉及香蕉RS合成核心基因挖掘、转录因子调控核心基因表达影响RS合成分子机制、功能鉴定及分子育种等方面的研究明显滞后。本文对1982年以来香蕉RS在细胞学、生理生化、食品加工、分子生物学等方面工作进展进行了回顾和展望。

Resistant starch(RS)is defined as the total amount of starch and the products of starch degradation that resists digestion and absorption in the small intestine of the healthy human body within 120 min,but it can be fermented in the large intestine.It provides many health benefits for humans,such as preventing diabetes,improving the intestinal microenvironment,reducing blood sugar,blood fat and weight,thus sparking great interest of scholars in multiple fields such as agriculture,food and medicine.RS has become one of the hot topics in crop nutrition quality improvement and healthy food research.According to the different chemical structures,sources and properties,RS can be divided into five types:RS_(1),RS_(2),RS_(3),RS_(4) and RS_(5).Banana is the world’s largest traded fruit,the fourth largest food crop,and a source of carbohydrates for two billion people worldwide.Banana RS belongs to the RS_(2) type and is the only RS identified as dietary fiber by the US Food and Drug Administration.Banana fruit is rich in RS,with a content of over 40%in unripen fruit,which is much higher than that in rice(<3.0%),wheat(<3.5%),high amylose corn(<22.4%)and other crops.Banana is a direct source of functional food.Since British physiologist Englyst first discovered and named RS in 1982,significant progresses have been made in bananas in terms of the morphological characteristics of RS granules,effects of processing conditions and complexation reaction on the morphological characteristics of RS granules,the relationship between accumulation and degradation characteristics and fruit quality,preparation methods and applications in food processing.However,compared to cereal crops like rice,studies on the core genes involved in RS synthesis,regulation mechanisms of transcription factors for the core genes expression influencing RS synthesis,functional identification,and molecular breeding in banana are significantly lagging behind.The previous work on the cytology,physiology and biochemistry,food processing,molecular biology of banana RS since 1982 is reviewed,and prospect for future work is put forward.