Optimization of synbiotic yogurts with yacon pulp (Smallanthus sonchifolius) and assessment of the viability of lactic acid bacteria

Abstract

The aim of this study was check the effects of sugar, yacon pulp and skimmed milk powder in the aroma, flavour, texture, appearance, overall impression and intent to purchase on synbiotic yogurts to optimize the formulation using Response Surface Methodology. The most accepted formulations were subjected to viability tests during 21 days by counting traditional and probiotic bacteria. Were constructed a complete 2 3 factorial design, totalling 17 experiments, and considered independent variables (percentage of ingredients) and dependent variables (sensory attributes). All attributes were graded using an acceptability assessment, for this balanced incomplete block was applied. The number of viable cells was determined using specific culture medium for each species. The percentage of yacon pulp had a pronounced negative influence on flavour, texture, appearance, overall impression and intent to purchase. Model predictions adjusted to the variables aroma, flavour, texture, appearance, overall impression and intent to purchase exhibited good predictive ability and hence could be used as tools for process control. Traditional bacterial strains and probiotic remained viable throughout the storage period. The counts of probiotic bacterial in the formulations were above 6 log CFU/g. The addition of Lactobacillus paracasei ssp. paracasei LBC 81 and yacon pulp to yogurt increased product acceptability.Keywords: response surface methodology; fructo-oligosaccharides; L. paracasei ssp. Paracasei LBC 81; sensory analysis.Practical Application: The innovations of this study are to develop a product with high fructooligosaccharides content originating from the yacon, largest source of fos of nature, and with great potential for cultivation in the Northeast of Brazil. The important points of this were using amounts of ingredients that would allow the acceptance of the product without cripple the growth of probiotic as well as maintain a high score of L. paracasei ssp. paracasei LBC 81 throughout the storage period, which is considered to be a challenge in food industry.

Drying of ‘yacon’ pretreated by pulsed vacuum osmotic dehydration

“…Scher et al (2009) observed that the inulin content decreased significantly after 'yacon' drying, and they concluded that such a decrease could be due to its hydrolysis, improved by these conditions. As previously mentioned, this degradation is undesirable since fructan presents a wide range of functional properties (Padilha et al, 2017).…”

“…A reduction in the fructan concentration was expected in all the treatments once fructan oxidation occurs due to the exposure to light and heat, with the FR ranging from 16.84 to 37.72%. Such fructan losses in osmotic experiments (OD -VD and OD -CD) are related to the natural leaching flux that occurs in osmotic processes once this saccharide possesses a hydrophilic nature and migrate from the internal tissue to the osmotic media (Oliveira et al, 2016;Padilha et al, 2017).…”