Abstract:

Passion fruit pomace, a by-product from passion fruit juice processing, was fermented with a mixed strain of Lactobacillus bulgaricus and Streptococcus thermophilus to prepare dietary fiber. To maximize soluble to total dietary fibre ratio (SDF/TDF ratio), the optimal fermentation process of passion fruit pomace was investigated using single factor method combined with orthogonal array design. In addition, the physico-chemical properties of dietary fiber obtained were analyzed. Results showed that the optimal fermentation conditions were determined as follows: 5% mixture of Lactobacillus bulgaricus and Streptococcus thermophilus, 1:10 of solid/liquid ratio, 33 ℃ of fermentation temperature and 21 h of fermentation time. The soluble dietary fiber (SDF) content was up to (29.01±0.41)% under the optimal fermentation conditions, which was higher than that obtained by chemical methods. Therefore, this fermentation method yields passion fruit dietary fibre with better water-holding capacity compared with chemical methods, but there is no obvious difference in expansion capacity.

Key words: passion fruit residue, fermentation, dietary fiber