Abstract
A natural sap from mature coconut palm known as coconut neera is enriched with essential minerals and vitamins. Rapid microbial fermentation affects neera processing industries because it spoils the physicochemical properties. There are various methods in preservation that extend the shelf life of coconut neera. The addition of nisin is one of the methods which protect neera against fermentation. Therefore, the study is focused to identify the effective combination of nisin (50 ppm) with preservatives like sodium benzoate (500, and 1000 ppm), and calcium carbonate (2500, and 3000 ppm) at two different combinations in neera. At the end of 21 d, 3000 ppm calcium carbonate with 50 ppm nisin in N4 treatment had an effective reduction of 120 × 105 CFU/ml and 143 × 102 CFU/ml for total bacteria and total yeast count. The reduced microbial survival resulted in the pH of 10.45 ± 0.05, total soluble solids of 15.43 ± 0.12 °Brix, and total acidity of 1.11 ± 0.04 mg/ L, at this combination. The treatment of nisin with 3000 ppm calcium carbonate demonstrated the high red fluorescence bacterial cells than the treatment of nisin with 1000 ppm sodium benzoate. Additionally, the microorganisms in N4 treatment precipitated 65.34% Ca2+ from 79.96% in XRF intensity analysis. The synergistic effect of nisin and calcium carbonate explored their antimicrobial activity against the heterogeneous microbial population in coconut neera. The concentration of 3000 ppm calcium carbonate and nisin 50 ppm preserves the physicochemical and sensory qualities, up to 21 d at 4°C, and offer hope for the industrial-scale implementation.
Highlights
The inflorescence sap of coconut neera is the abundant source of sucrose (16.19 g/ 100 mL), minerals such as K-68.4 mg/ 100 mL, Na90.6 mg/ 100 mL, P-3.9 mg/ 100 mL, vitamins and proven low glycemic index drink (GI-35) with added medicinal benefits of nephroprotective, and hepatoprotective activity.[1]
Addition of preservatives against the microbial growth in neera The microbial population analysis in plate count revealed that the reduced total bacteria, and yeast count in N4 treatment than the N3 treatment (Table 1)
The added concentration of 3000 ppm calcium carbonate in N4 treatment suppressed the microbial growth in highest count such as 120 × 105 CFU/ml for total bacteria and 143 × 102 CFU/ml for yeast at the end of the storage period (21 d)
Summary
The inflorescence sap of coconut neera is the abundant source of sucrose (16.19 g/ 100 mL), minerals such as K-68.4 mg/ 100 mL, Na90.6 mg/ 100 mL, P-3.9 mg/ 100 mL, vitamins and proven low glycemic index drink (GI-35) with added medicinal benefits of nephroprotective, and hepatoprotective activity.[1]. The bio-preservative nisin (E234) from Lactococcus lactis classified as “Generally Recognized as Safe” for the food industry by World Health Organization has antimicrobial peptides that are widely used against gram-positive organisms and spores.[8] Previous study reported that the application of nisin at a maximum concentration of 100 μg/ mL in wine effectively inhibited lactic acid fermentation.[9] the microbial inactivation mechanism of ion-permeable pores in the cytoplasm is reported mainly for gram-positive bacteria than gram-negative bacteria.[10] their combination with chemical preservatives can affect the heterogeneous microbial (grampositive, gram-negative bacteria, yeast) growth in neera. Earlier studies reported that nanoparticles of calcium carbonate showed antimicrobial activity for gram-positive and gram-negative bacteria. The study in black olive fermentation reported that 1000 ppm of sodium benzoate reduced the yeast count upon storage.[13] the current study is aimed to control heterogeneous microbial communities of neera by nisin in combination with preservatives (sodium benzoate, and calcium carbonate), and assess the quality changes during storage
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