Research Progress of Banana Resistant Starch

Abstract

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: RS1, RS2, RS3, RS4 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 RS2 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.

Keywords

• banana
• resistant starch
• structure characteristics
• accumulation feature
• molecular breeding