Polyol-producing lactic acid bacteria isolated from sourdough and their application to reduce sugar in a quinoa-based milk substitute

• Published in: International journal of food microbiology Vol. 286; pp. 31 - 36
• Main Authors: Jeske, Stephanie, Zannini, Emanuele, Lynch, Kieran M., Coffey, Aidan, Arendt, Elke K.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 02.12.2018; Elsevier BV
• Subjects: Acetic acid; Acetic Acid - metabolism; Amylolytic enzymes; Bacteria; Beverages; Biotechnology; Chenopodium quinoa - metabolism; Conversion; Enzymes; Fermentation; Food science; Fructose; Fructose - metabolism; Glucose; Glucose - metabolism; Glycaemic index; Lactic acid; Lactic Acid - metabolism; Lactic acid bacteria; Lactobacillus brevis - isolation & purification; Lactobacillus brevis - metabolism; Leuconostoc - isolation & purification; Leuconostoc - metabolism; Mannitol; Mannitol - metabolism; Microbiology; Milk; Milk substitute; Milk Substitutes - chemistry; Plant-based beverages; Polylactic acid; Polymers - metabolism; Quinoa; Reduction; Sourdough; Strains (organisms); Substitutes; Sugar; Sugar reduction; Sugars - metabolism; Sweetness; Quinoa; QBMS; Lactic acid bacteria; Sugar reduction; Milk substitute; Mannitol; PBMS; Glycaemic index
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2018.07.013

The interest for plant-based dairy substitutes is expanding rapidly and consumers are opting for nutritious and healthy dairy alternatives. The reduction of sugar using different exogenous enzymes in combination with lactic acid fermentation in a quinoa-based milk substitute was explored in this study. Different amylolytic enzymes were used to release sugar from the raw material, which were further metabolised to mannitol, due to fermentation with two heterofermentative lactic acid bacteria. Using these two biotechnological techniques enables the reduction of sugar, while also preserving some of the sweetness. Leuconostoc citreum TR116, and Lactobacillus brevis TR055 were isolated from sourdough. Both strains showed high viable cell counts with L. citreum TR116 > 8.4 and L. brevis TR055 > 9.3 log cfu/mL, and a reduction in pH to 3.7 and 3.5 respectively. When fructose was available, mannitol was produced in conjunction with acetic acid in addition to lactic acid. Due to these processes, the original glucose value was reduced from 50 mmol/100 g to approximately 30 mmol/100 g, which equates to a glucose reduction of 40%. In respect to mannitol production, both strains performed well: L. citreum TR116 showed a conversion factor of 1:1 from fructose to mannitol, while L. brevis TR055 showed a lower yield, with a conversion factor of 1:0.8. Glycaemic load was reduced by more than a third, bringing it down to the low range with a value of about 10. Overall, enzymatic modification in conjunction with mannitol-producing lactic acid bacteria shows great potential for further possible application in the development of nutritious and sugar reduced plant-based milk substitutes. •Quinoa served as a good substrate, facilitating the growth of L. citreum TR116 and L. brevis TR055.•Exogenous amylolytic enzymes in combination with lactic acid fermentation enabled the reduction of glucose by 40%.•Mannitol was produced with high conversion factors from fructose.•Glycaemic load was reduced by more than a third.