Affiliation:
1. Department of Chemistry, Biotechnology and Food Science (IKBM), Norwegian University of Life Sciences (UMB) Ås, Norway
2. Department of Food Technology and Nutrition, Makerere University, Kampala, Uganda
3. Nofima AS, Norwegian Institute of Food, Fisheries and Aquaculture, Ås, Norway
Abstract
ABSTRACT
Amylolytic lactic acid bacteria (ALAB) can potentially replace malt in reducing the viscosity of starchy porridges. However, the drawback of using ALAB is their low and delayed amylolytic activity. This necessitates searching for efficient ALAB and strategies to improve their amylolytic activity. Two ALAB,
Lactobacillus plantarum
MNC 21 and
Lactococcus lactis
MNC 24, isolated from
Obushera
, were used to ferment starches in MRS broth: sorghum, millet, sweet potato, and commercial soluble starch. The amylolytic activity of MNC 21 was comparable to that of the ALAB collection strain
Lb. plantarum
A6, while that of MNC 24 was extremely low. MNC 21, MNC 24, and their coculture were compared to A6 and sorghum malt for ability to ferment and reduce the viscosity of sorghum porridge (11.6% dry matter). ALAB and the coculture lowered the pH from 6.2 to <4.5 within 12 h, while malt as a carrier of wild starter took about 20 h. Coculturing increased lactic acid yield by 46% and 76.8% compared to the yields of MNC 21 and MNC 24 monocultures, respectively. The coculture accumulated significantly larger (
P
< 0.05) amounts of maltose and diacetyl than the monocultures. Sorghum malt control and the coculture hydrolyzed more starch in sorghum porridge than the monocultures. The coculture initiated changes in the rheological parameters storage modulus (
G
′), loss modulus (
G
″), phase angle (δ), and complex viscosity (η*) earlier than its constituent monocultures. The shear viscosity of sorghum porridge was reduced significantly (
P
< 0.05) from 1950 cP to 110 cP (malt), 281 cP (coculture), 382 cP (MNC 21), 713 cP (MNC 24), and 722 cP (A6). Coculturing strong ALAB with weak ALAB or non-ALAB can be exploited for preparation of nutrient-dense weaning foods and increasing lactic acid yield from starchy materials.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
11 articles.
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