Enhancing the nutritional profile of purple sweet potato flour through fermentation with Lactiplantibacillus plantarum InaCC B157: A functional food perspective.

Abstract

Background and aim: Purple sweet potatoes (Ipomoea batatas var. Ayamurasaki) possess high nutritional potential due to their rich content of amino acids, minerals, and fatty acids. However, their nutritional profile can be further improved through fermentation. This study aimed to evaluate the ability of Lactiplantibacillus plantarum InaCC B157 to enhance the biochemical and functional composition of purple sweet potato flour.

Materials and methods: Six L. plantarum strains were screened for enzymatic activities. The strain with the highest amylolytic, proteolytic, and qualitative cellulolytic activity (InaCC B157) was selected for solid-state fermentation of purple sweet potato flour. Fermented Ipomoea batatas flour (FIB) and unfermented Ipomoea batatas flour (UIB) samples were analyzed for amino acid, mineral, and fatty acid content, along with vitamins A and C, dietary fiber, antioxidants, and bioactive compounds. Microstructure was examined using scanning electron microscopy (SEM). Data were statistically analyzed using a one-way analysis of variance and Duncan's multiple range test.

Results: Fermentation significantly increased the levels of essential amino acids - histidine, threonine, valine, methionine, cysteine, isoleucine, leucine, and phenylalanine (excluding lysine) - and non-essential amino acids, including glutamine, serine, glycine, and tyrosine. Mineral concentrations of zinc, calcium, potassium, magnesium, and phosphorus improved by up to 17.65%, while copper decreased. Linoleic and linolenic acids increased by 55.5% and 100%, respectively. Protein, fat, carbohydrates, fiber, and vitamins A and C also increased, while ash, anthocyanins, phenols, and steroids showed a decline. Antioxidant activity increased by 13.7%. SEM analysis revealed no substantial morphological differences between FIB and UIB.

Conclusion: Fermentation of purple sweet potato flour with L. plantarum InaCC B157 significantly enhanced its nutritional value, particularly amino acid, mineral, and essential fatty acid profiles. These findings support the potential application of fermented purple sweet potato as a functional food and sustainable feed ingredient. Limitations include the lack of sensory evaluation and long-term stability data. Future studies should investigate sensory profiling, shelf-life extension, and optimization of fermentation parameters to further enhance the application of this functional ingredient.