Changes in the Profile of Organic Acids in Plain Set and Stirred Yogurts During Manufacture and Refrigerated Storage1

Abstract

The organic acids profile in femented dairy foods is an indicator of the metabolic activity of added bacterial cultures. These acidr act as natural preservatives and contribute to the characteristic sensory properties. This study was done to determine the fleet of encapsulation on the metabolic activity of probiotic supplements, i. e. bifidobmeria, in plain yogurts. Metabolically active bijidohcteria may increase the concentration of certain organic acids, mainly acetic and propionic acids, which might lead to decreased acceptability of the product. Changes in the proBles of organic acids were determined in plain set and stirred-type yogurts containing the starter culture and microencapsulated and nonencapsulated probiotic strains of either Bifidobacterium longum B6 or B . longum ATCC 15708. Ion-exchange high-pevormance liquid chromatography was used for the separation and quantification of the organic acih. Concentrations of acetic and lactic acid increased during storage, while those of citric and uric acid remained stable. No particular pattern was observed for propionic or butyn'c acid, while pyruvic acid initial& decreased and then increased during storage.

An investigation of the volatile compound profiles of probiotic yogurts produced using different inulin and demineralised whey powder combinations

“…The highest mean concentration of acetic acid was present in yogurt sample E, followed in descending order by yogurt samples D, F, A, G, H, C, and B, (Table 1). Acetic acid was previously identified in yogurt by Beshkova et al (15) and Adhikari et al (27).…”

Technology and potential applications of probiotic encapsulation in fermented milk products

“…This fact was attributed to changes in the metabolic pathways of the encapsulated cells which caused production of small-bitter peptides (Truelstrup Hansen et al 2002). Adhikari et al (2002) observed that encapsulation lowered the acetic acid content in yoghurt significantly if bifidobacteria were added to the product before fermentation. Acetic acid produced by Bifidobacterium spp.…”

“…Then, the produced emulsion is broken by adding CaCl 2 and the produced microcapsules are collected by centrifugation. Sodium alginate, κ-carrageenan with KCl as the emulsion breaker and genipin cross-linked gelatin can be used to microencapsulate probiotic bacteria by emulsion method (Adhikari et al, 2002;Adhikari et al, 2000;Annan et al, 2008). It has been reported that concentration and viscosity of the encapsulation mix before gelation, agitation rate of mixture and type of emulsifier used are the main important parameters which control the diameter of the final formed microbeads.…”

Organic acids profiles in lactose-hydrolyzed yogurt with different matrix composition

“…In addition, the citric, uric, hippuric, and orotic acids have been found in yogurts, as they are natural compounds of milk. Some of them contribute to yogurt flavor directly or indirectly through the formation of intermediate compounds and act as preservatives (Fernandez-Garcia and McGregor 1994;Adhikari et al 2002;Tamime and Robinson 2007). Despite all these changes, yogurt still contains significant and variable amounts of intact lactose depending on the milk formulation, as only a part of the lactose (~20-30%) is metabolized (Tamime and Robinson 2007).…”