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Title: Characterization of the microbial diversity in yacon spontaneous fermentation at 20 ºC

Author
item REINA, LAURA - NORTH CAROLINA STATE UNIVERSITY
item Perez Diaz, Ilenys
item Breidt, Frederick
item AZCARATE-PERIL, MARIA ANDREA - UNIVERSITY OF NORTH CAROLINA
item MEDINA, EDUARDO - NORTH CAROLINA STATE UNIVERSITY
item BUTZ, NATASHA - UNIVERSITY OF NORTH CAROLINA

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2015
Publication Date: 6/12/2015
Publication URL: http://handle.nal.usda.gov/10113/61597
Citation: Reina, L., Perez Diaz, I.M., Breidt, F., Azcarate-Peril, M., Medina, E., Butz, N. 2015. Characterization of the microbial diversity in yacon spontaneous fermentation at 20 ºC. International Journal of Food Microbiology. 203:35-40. 10.1016/j.ijfoodmicro.2015.03.007.

Interpretive Summary: Yacon is an Andean root with known medicinal properties. The root has a sweet taste and crisp texture and is consumed raw, boiled, baked or as juice. The yacon is now considered a functional food due to its fructooligosaccharides and polyphenol contents. It is also rich in reducing sugars, amino acids and minerals. Thus, yacon has a considerable potential to make value-added products in combination with cucumber pickled products. This research reports on the dominant indigenous microbiota present in yacon fermentation. Lactic acid bacteria of the Leuconostoc genera leads yacon fermentation with 2% sodium chloride. However, yacon fermentation with 4% sodium chloride seems to be dominated by Lactobacillus spp. Thus, hybrid products of fermented yacon and cucumbers could be potentially manufacture with 2% sodium chloride and a leuconostoc starter culture or with 4% sodium chloride and a lactobacillus starter culture.

Technical Abstract: The prebiotic fructooligosaccharide content of yaconmakes this root an attractive alternative for the supplementation of a variety of food products. The preservation of yacon by fermentation has been proposed as an alternative to increase the probiotic content of the root concomitantlywith its shelf life. Thus the fermented yacon could have significant functional content. The objective of this research was to characterize the biochemistry and microbiology of spontaneous yacon fermentation with 2% NaCl and define the viability of the proposed process. The biochemical analysis of spontaneous heterolactic fermentation of yacon showed a progressive drop in pH with increased lactic and acetic acids, and the production of mannitol during fermentation. The microbial ecology of yacon fermentation was investigated using culture-dependent and culture-independent methods. Bacterial cell counts revealed a dominance of lactic acid bacteria (LAB) over yeasts, which were also present during the first 2 days of the fermentation. Results showed that the heterofermentative LAB were primarily Leuconostoc species, thus it presents a viable method to achieve long term preservation of this root.