Folate fortification of skim milk by a probiotic Lactococcus lactis CM28 and evaluation of its stability in fermented milk on cold storage

Abstract

In order to enhance folate levels in fermented foods, a folate producing probiotic lactic acid bacterium isolated from cow's milk and identified as Lactococcus lactis CM28 by 16S rRNA sequencing was used to fortify skim milk. Optimization of medium additives such as folate precursors, prebiotics and reducing agents along with suitable culture conditions enhanced folate levels in skim milk. Optimization resulted in a four fold increase in the extracellular folate (61.02 ± 1.3 μg/L) and after deconjugation the total folate detected was 129.53 ± 1.2 μg/L. The effect of refrigerated storage on the viability of L. lactis, pH, titratable acidity (TA) in terms of percentage lactic acid and finally on the stability of folate was determined. Only a slight variation in pH (4.74 ± 0.02 to 4.415 ± 0.007) and acidity (0.28 ± 0.028 to 0.48 ± 0.014 %) was noted during folate fermentation. During storage, only less than a log unit reduction was noted in the viable count of the probiotic after 15 days and about 90 % of the produced folate was retained in an active state.

Fermentation of Milk Using Folate-Producing Lactic Acid Bacteria to Increase Natural Folate Content: A Review

“…26 Furthermore, the oxidation will reduce folate bioavailability due to the conversion of folate into an inactive form, p-aminobenzoyl glutamate, significantly reducing its activity. 20 Compared to natural folate present in the reduced form, folic acid is in the fully oxidized monoglutamate form. Shown in Figure 1b, the structure of folic acid is similar to the natural folate form but has fewer hydrogen atoms.…”

“…Both strains can produce folate without PABA supplementation because they have all the genes needed in the shikimate pathway and the conversion of chorismate into PABA. 7,20,21,57 The production of extracellular folate by LAB such as L. lactis can be increased by adding PABA as a folate precursor. The high amount of PABA can inactivate folypolyglutamate synthetase, which functions in the extension of the polyglutamic tail in folate molecules.…”

“…before being absorbed by the body. 12,20,21 Therefore, extracellular folate secreted to the media can be effectively and readily used as an alternative source of natural folate.…”

“…24 The ability of LAB to produce folate depends on fermentation conditions, medium types, the presence of folate precursors, and several other factors. 17,20 In this review, the utilization of LAB in increasing natural folate content in fermented milk products that could be used to prevent folate deficiency will be discussed.…”

Encapsulated Lactococcus lactis with enhanced gastrointestinal survival for the development of folate enriched functional foods

“…Folate quantification was carried out by microbiological assay using the folate auxotroph Lactobacillus casei NCIM2364 as the indicator organism as described before (Divya and Nampoothiri, 2014;Horne, 1997).…”