- The current state of the banana industry in Vietnam
Vietnam is currently ranked among the top 15 countries with the largest banana production globally. However, due to the physiological characteristics of being a climacteric fruit, bananas ripen very quickly after harvest, leading to a decline in both nutritional and sensory quality. This poses challenges for preservation, increases post-harvest losses, and limits export potential.
Among various banana varieties, the Tieu Hong Cavendish banana stands out for its high economic value, firm flesh, and premium flavor. The application of tissue culture technology has helped increase yields by 10–20%. To optimize value and minimize loss, processing green bananas into flour and resistant starch is emerging as a highly promising direction.
- Outstanding advantages of green bananas
Unlike ripe bananas, green bananas contain 70–80% starch (based on dry weight). Notable health benefits include:
- Low Glycemic index (GI): Below 40%, which helps stabilize blood sugar levels, making it suitable for diabetic patients.
- Rich in micronutrients: High Potassium content supports the nervous system, while Vitamin C and B6 help regulate hemoglobin and blood sugar levels.
- Supports digestion and weight management: High fiber content helps prevent diarrhea and creates a prolonged feeling of fullness, aiding those with obesity.
- Potential alternative source: Can serve as a substitute for traditional starches such as corn, wheat, and rice.
- Resistant Starch (RS) - The "Superfood" from Green Bananas
The primary component of green bananas is starch, accounting for 70-80% of their dry weight. During the ripening process, this starch is converted into sugars such as sucrose, fructose, and glucose, which make up about 16% of the fresh weight. Green bananas have a low Glycemic Index (GI) compared to ripe ones, typically below 40%-due to their high starch and fiber content, which helps minimize blood sugar spikes. Additionally, green bananas are rich in potassium, supporting efficient nervous system function. They also contain essential vitamins such as Vitamin C and Vitamin B6. Specifically, Vitamin B6 aids in hemoglobin production and effective blood sugar regulation.
One of the leading health benefits of green bananas is their high fiber content, which promotes a healthy digestive system, supports diarrhea prevention, and is ideal for diabetic diets and effective weight loss for those struggling with obesity. The highest starch content is found in green, unripe fruits like bananas and mangoes, reaching up to 70% of their dry matter. Consequently, green bananas can serve as a viable alternative to traditional sources like corn, wheat, and rice starch.
Notably, the starch in green bananas contains an exceptionally high proportion of resistant starch - the highest among all fruits at 48.99g/100g (Langkilde et al., 2002; Falosolin et al., 2007). Therefore, researching the production of green banana flour and starch for application in dietary food products is highly effective.
Resistant starch is defined as starch and its degradation products that remain undigested as they pass through the small intestine. It occurs naturally or can be added to food through synthetic resistant starch varieties.
Certain types of resistant starch (RS1, RS2, and RS3) are fermented by microorganisms in the large intestine to produce short-chain fatty acids and increase bacterial biomass, providing significant benefits to human health. In many ways, resistant starch exerts physiological effects similar to dietary fiber, acting as a mild laxative.
The concept of resistant starch originated from studies in the 1970s, in which researchers categorized starch into three types: rapidly digestible starch, slowly digestible starch, and resistant starch. Supported by the Commission of the European Communities, research further defined and classified resistant starch into four categories:
(1) RS1, physically inaccessible starch, found in seeds or legumes and unprocessed whole grains.
(2) RS2, resistant starch naturally protected from digestive enzymes due to its structure, such as high-amylose maize starch.
(3) RS3, retrograded starch formed when starch-containing foods are cooked, making soluble starch less soluble, such as in pasta.
(4) RS4, chemically modified starch designed to resist digestion.
It is important to note that food processing can significantly affect the resistant starch content of food. Generally, processing tends to decrease RS levels; for instance, whole wheat contains 14% resistant starch while milled wheat flour contains only 2%, and RS in cooked rice is typically lower than in raw rice. However, certain processing methods can increase RS content. For example, while gelatinized starch is easier to digest, retrograded starch formed during cooling can create resistant starch that evades digestive enzymes (RS3 or retrograded starch). Potato salad or boiled potatoes often have higher RS levels than typical processed potatoes. Since resistant starch is indigestible, it does not release glucose in the small intestine but instead passes directly to the large intestine to be fermented and digested by colonic bacteria. This fermentation process produces short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate, while increasing bacterial mass. Butyrate serves as the primary energy source for colonocytes, enhances metabolism, reduces inflammation, and reduce stress.
These short-chain fatty acids are then rapidly absorbed and metabolized in intestinal epithelial cells, the liver, or other tissues. Consequently, foods containing resistant starch have a low glycemic index (GI) and do not cause sudden blood glucose spikes. As a result, in 2016, the FDA approved the claim that resistant starch may reduce the risk of type 2 diabetes.
Resistant starch also reduces the risk of colorectal cancer through various mechanisms, such as protecting against DNA damage, altering gene expression, and promoting apoptosis (programmed cell death) in cancer cells.
Green bananas are a precious source of resistant starch. The starch in green bananas has an exceptionally high ratio of resistant starch, the highest among all fruits.
Therefore, using green Tieu Hong Cavendish bananas as raw materials for processing green banana flour and starch not only minimizes post-harvest losses but also provides high health benefits, such as improving gastrointestinal conditions, promoting efficient colon function, supporting weight loss, and reducing insulin sensitivity.
- Production Process and Applications
Research has identified the optimal technical parameters for obtaining high-quality green banana starch:
- Harvest maturity: 90 days after flowering is the ideal time.
- Material treatment: Use 1.5% Citric Acid for 20 minutes to treat the raw material, which helps improve color and quality.
- Sedimentation and washing process: Performed 4 times to ensure purity.
- Drying conditions: Dried at 60°C for 7 hours.
- Practical Applications: Modified green banana flour and starch can partially replace traditional starches in food production, such as:
- Bread and pastries.
- Noodles, vermicelli, and Pho noodles.
- Dietary supplements.
Conclusion
Developing products from green Tieu Hong Cavendish bananas is not only a technical solution to reduce post-harvest losses but also creates a valuable raw material source for the health food industry, contributing to the enhancement of Vietnamese agricultural value.
Original author: Hoang Thi Minh Nguyet - Faculty of Food Science and Technology.
https://cntp.vnua.edu.vn/tin-tuc-va-su-kien/nguon-tinh-bot-khang-tu-chuoi-tieu-hong-san-pham-va-ung-dung-43391
