Flaxseed Soluble Dietary Fibre Enhances Lactic Acid Bacterial Survival and Growth in Kefir and Possesses High Antioxidant Capacity

Abstract

This study investigated the capability and efficiency of flaxseed soluble dietary fibre /mucilage to enhance bacterial survival and growth in kefir as well as the antioxidant activity of the mucilage. Crude flaxseed mucilage was extracted using a microwave method, followed by enzymatic and dialysis treatments to obtain pure mucilage. The antioxidant activities of the pure and crude mucilage were measured using different assays. Microbial analyses, pH and total titratable acidity (TTA) were measured in kefir samples, supplemented with probiotic bacteria ( Lactobacillus acidophilus and Bifidobacterium lactis) and pure or crude flaxseed mucilage during 28 cold storage periodat 4 ºC. The results showed that for all kefir samples, the total bacteria counts were above7.9 log cfu/mL at the end of cold storage period. However, kefir samples supplemented with pure flaxseed mucilage enhanced significantly (P < 0.05) higher viability of bacteria (9.5 log cfu/mL) and acidity (0.78% TTA). An overall pH decline of 0.2 was observed during cold storage period. The total phenolic content (TPC) in crude mucilage was significantly (P < 0.05) higher than pure mucilage (10.5 ± 0.2 and 5.7 ± 0.1 mg Gallic acid equivalent /g flaxseed, respectively). The mucilage from crude flaxseed exhibited strong antioxidant activity; Oxygen Radical Absorbance Capacity (ORAC) value of 51.2 ± 3.3 ?mol Trolox equivalent /g, 53.7 ± 2.8% discoloration for 2,2-diphenyl-1-picrylhydrazyl (DPPH), and 68.3 ± 9.2% Beta-Carotene bleaching which was well in agreement with high TPC. This study demonstrated that flaxseed mucilage acts as a good source of prebiotic, enhancing lactic acid bacteria growth in kefir model in addition of their high antioxidant beneficiary.