Peruvian tocosh may offer lactic acid bacteria with ‘biotechnological interest’

By Stephen Daniells contact

- Last updated on GMT

© Getty Images / Hunter Trick
© Getty Images / Hunter Trick
Potatoes tocosh – an ancestral fermented food product from the Central Peruvian Andes – may offer food scientists with novel bacterial cultures for the production of fermented starchy products.

Data published in LWT - Food Science and Technology​ indicated that Lactobacillussakei​ and Leuconostoc mesenteroides​ were present in all the samples.

Several strains of Lactobacillus sakei​ and Leuconostoc mesenteroides​ displayed amylase and phytate-degrading abilities, while some also produced riboflavin and folate, reported scientists from Universitat de València (Spain) the Instituto de Agroquímica y Tecnología de Alimentos (Spain), the Centro de Referencia para Lactobacilos (Argentina) and the Universidad Nacional Agraria La Molina (Peru).

“To the best of our knowledge, this is the first study focusing on the [Lactic acid bacteria] community structure of the Andean traditional tocosh by using culture-dependent and [high throughput sequencing] approaches,” ​they wrote.

“The microbial profile revealed Lb. sakei and Ln. mesenteroides as the main LAB species occurring during fermentation. Based on their functional and safety characterization, strains with valuable features for further design of functional starchy fermented foods were selected.

“Maintenance and promotion of indigenous Andean culture is crucial for ensuring protection of traditional agroecological systems and agrobiodiversity.”

Tocosh

Tocosh is still prepared in small communities in the Andes by placing potatoes between layers of straw in a well dug near a water spring. The potatoes and straw are covered with rocks, and the left to ferment for 12 months.

“After this time, potatoes suffer an enzymatic browning and are laid in a dry shaded area to allow the water to drain,”​ explained the authors of the new paper. “The obtained product is kept for consumption, sale or most commonly, as a sun-dried and ground fine flour-type product that is used to prepare different broths, stews and “mazamorra” which is a semi-liquid food with thick consistency.”

Very few studies have examined the microbiological profile of these foods, with preliminary data showing that lactobacilli dominate.

New study data

Samples taken before fermentation, and again after one and eight months. The researchers identified 24 specied of lactic acid bacteria and recovered six by culturing: Lactobacillus sakei, L. casei, L. farciminis, L. brevis, L. fermentum​, and Leuconostoc mesenteroides​.

While lactic acid bacteria predominated on fresh potatoes, the researchers found that Clostridium, Zymophilus​ and Prevotella​ were the most abundant genus in both one and eight month tocosh samples, said the researchers. It should be stressed that none​ of the “clostridia species detected in tocosh is pathogenic to humans or produce toxins; therefore, they do not compromise tocosh safety”​, they added.

“Safety traits of major [lactic acid bacteria] species from tocosh showed antibacterial activities as well as biogenic amines production capacity,” ​wrote the researchers.

“The molecular inventory achieved by [high throughput sequencing] approach provided information on [lactic acid bacteria] population composition during fermentation of this ancestral potato fermented product while culturing allowed the selection of [lactic acid bacteria] strains suitable for novel functional cultures design for the production of fermented starchy products.”

Source: LWT - Food Science and Technology
Volume 87, Pages 567-574, doi:
“Exploring diversity and biotechnological potential of lactic acid bacteria from tocosh - traditional Peruvian fermented potatoes - by high throughput sequencing (HTS) and culturing”
Authors: E. Jiménez

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