Effect of fermentation in nutritional, textural and sensorial parameters of vegan-spread products using a probiotic folate-producing Lactobacillus sakei strain

Highlights

• Spread vegan products made with Andean potato, amaranth and chia were fermented.

• A probiotic folate-producing strain improved vitamin content through bio-enrichment.

• Nutritional, textural, structural and sensorial features were studied.

• No changes in firmness, viscosity or syneresis occurred in fermentation and storage.

Abstract

Folates are essential vitamins for human life and must be taken as part of the diet. It is known that some lactic bacteria are capable to produce folates during fermentation, which represents an interesting strategy as alternative to fortification with folic acid. The aim of this work was to study the effect of fermentation with a probiotic folate-producing Lactobacillus sakei strain in vegan spread products. Two products were manufactured with Andean potato and amaranth -with and without chia- and emulsified with other ingredients. Nutritional, textural, structural and sensorial analysis were performed. Products were also studied during 28 days of refrigerated storage. After 24 h fermentation bacterial growth achieved 11.0 log CFU/g and folate concentration reached 1900 ng/g, both values were kept during conservation period. No changes in firmness, viscosity, syneresis or particle size were observed after fermentation and storage, all parameters associated with products stability. Sensory analyses showed that the product without chia, fermented during 6 h, reached a good acceptability score, especially among vegetarian population. These results demonstrated the feasibility of bio-enrich novel spread vegan products throughout lactic fermentation with no changes in technological parameters.

Introduction

Folate is a term referring to a family of compounds which belong to the B vitamin group and are essential elements for life. In human pathology, folate deficiency is associated with megaloblastic anemia, cardiac diseases and neural tube malformations in newborns, among others (Iyer & Tomar, 2009). This vitamin is necessary for basic cellular functions related with amino acid metabolism, nucleotide biosynthesis, and methylation cycle. Unlike plants and some microorganisms, humans are not able to synthesize folate de novo, and must be acquired entirely from dietary sources (Savoy & LeBlanc, 2018).

Folate deficiency is frequent worldwide, both in developing and developed countries (Youngblood et al., 2013). Folic acid, a synthetic form of folate, is used as oral supplement and is also incorporated in cereals for food fortification in over 57 countries. Nevertheless, high intake of this compound has been associated with some adverse secondary effects, such as masking symptoms of vitamin B12 deficiency (Liew, 2016). A new interesting strategy as alternative to fortification with folic acid is the use of folate-producing microorganisms to bio-enrich fermented food (Savoy & LeBlanc, 2018).

In particular, it was demonstrated that certain lactic acid bacteria (LAB) are able to produce folate. However, this ability is a strain-dependent trait and varies considerably among strains. In addition, probiotic bacteria are good candidates, since they are able to survive through the gastrointestinal tract and adhere to the human intestinal cells, which may increase folate production in situ (Pompei et al., 2007). Thus, selection of folate-producing strains and optimization of the fermentation conditions are essential prerequisites to perform a proper biotechnological process to develop novel food products. Furthermore, studying the survival of probiotic bacteria in foods is important since the physicochemical and organoleptic properties of the product must remain stable during shelf-life as well as the probiotic microorganisms must stay viable (Soares et al., 2019).

Some vegetable substrates have been assessed to develop folate bio-enriched products, like oat, soy and wheat, among others (Saubade, Humblot, Hemery, & Guyot, 2018). In this way, Andean potato and amaranth are good starch sources, and the latter is also important due to its protein content (around 15%) with a good essential amino acid pattern, high lysine content and a biological value comparable to that of cheese (Bressani, de Martell, & de Godinez, 1993). In addition, chia seeds have an enormous potential of application in food since its mucilage can substitute emulsifiers and stabilizers and also provides omega 3, nevertheless some sensorial challenges are associated with its incorporation (Fernandes & Mellado, 2018).

A vegan-spread product was manufactured with the mentioned substrates and additives such as oil, using high speed shear to form an emulsion, which was fermented with a folate-producing Lactobacillus sakei strain. In general, fermentation can improve nutritional, functional and textural quality of foods. Nevertheless, some metabolites produced might be responsible of flavor and texture and fermentation parameters should be assessed to define optimal conditions.

Thus, the aim of this work was to study the effect of fermentation with a folate-producing L. sakei CRL2210 in two vegetable vegan spread products (with and without chia) in order to determine folate production and fermentation parameters. The effect of adding chia, in order to improve textural and nutritional values of these fermented foods, was also evaluated.