Control of rope spore forming bacteria using carambola (Averrhoa carambola) fruit pomace powder in wheat bread preparation
2016
Sudha, M.L. | Viswanath, P. | Siddappa, V. | Rajarathnam, S. | Shashirekha, M.N.
Wheat bread is a high moisture, low acid product, susceptible to spoilage by Bacillus spp., as the endospores survive the baking temperatures. Carambola (Averrhoa carambola) fruit pomace, a by-product obtained after juice extraction, has an insoluble dietary fibre content of 61.0±1.2% and is rich in antimicrobial phenolic compounds of 17.8±1.1 gallic acid equivalent/g (water extract). The anti-nutritional content of oxalic acid in the fruit is reduced to 0.15 mg/g in the pomace. Studies on the antimicrobial activity of the dried pomace powder in dimethyl-sulfoxide as determined by the disc diffusion assay showed that the Gram-positive bacteria tested were more sensitive than Gram-negative bacteria. The minimum inhibitory and minimum bactericidal concentration of Bacillus cereus and of Bacillus subtilis was 1.25 mg/ml of the dry pomace powder. Incorporation of carambola pomace powder into wheat flour for bread preparation at a 5% level resulted in a bread of acceptable sensory profile with a high desirable fibre content. The rope spore count of the bread with carambola fruit pomace powder at this level showed a count of 0.7 log₁₀/g, an inhibition equal to that of bread with chemical preservatives added while the bread with no preservatives had a count of 8.76 log₁₀/g at the end of 72 h when incubated at 35 °C, resulting in a product that was safe with added high fibre a desired nutrient quality.
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