Okara as a culture medium and stabilizing matrix for freeze-dried and spray-dried Lactobacillus plantarum

ESTEBAN GERBINO; GABRIEL QUINTANA; ANDREA GOMEZ-ZAVAGLIA

San Miguel de Tucuman

Simposio; V Simposio Internacional de Bacterias Lácticas (SIBAL); 2016

CERELA

Okara is a nutritionally valuable by-productobtained as result of soy milk elaboration. It is produced in large quantitiesand is very prompt to spoilage. To valorize this agro-waste, this work proposesthe use of okara as culture and dehydration medium for L. plantarum CIDCA 83114.As a first step, the centesimal compositionof freeze-dried okara was determined. Two types of okara were used: whole anddefatted okara, the latter obtained after extracting okara lipids with diethylether. Both dehydrated okara were suspended in water to obtain 5% w/wsuspensions, which were then autoclaved and used as culture media for Lactobacillus plantarum CIDCA 83114. Thegrowth kinetics of L. plantarum CIDCA83114 in whole and defatted okara were followed by plate counting and comparedwith those of bacteria grown in MRS (control).Once determined the culture conditions,bacteria in the stationary phase were neutralized and freeze-dried (with orwithout 250 mM sucrose) or spray-dried. Bacteria were plate counted immediatelyafter freeze-drying or spray-drying and during storage at 4oC for 90days.The growth kinetics showed no significantdifferences for bacteria grown in whole or defatted okara with regard to thecontrols. Regarding dehydration, freeze-dried microorganisms grown in wholeokara were those that best overcame the process. The addition of sucrose to thedehydration medium enhanced the recovery of microorganisms grown in defattedokara and in MRS after freeze-drying and did not have a significant effect onmicroorganisms grown in whole okara. In turn, bacteria grown in whole anddefatted okara showed a better performance than the controls afterspray-drying.Regarding storage, freeze-drying was the mostdetrimental process for bacteria grown in all the three culture media. Theaddition of sucrose improved the performance of microorganisms stored in thethree conditions. Regarding spray-drying, bacteria grown in whole and defattedokara showed a better performance than the controls. The mathematical fittingof the storage evolution allowed the description of three different groups a)bacteria showing no significant cultivability decays during storage; b)bacteria experiencing a linear decay; c) bacteria showing a non-linear decay.These mathematical equations allowed determining the times at which bacterialcounts were above 106 CFU/g, the concentration requested by EFSA forprobiotic products at the time of being consumed.The proposed strategy supports theuse of an agro-waste produced in large quantities as culture medium for L. plantarum CIDCA 83114. The good performance of okara as dehydration medium during freeze-dryingand spray-drying represents a further contribution to valorize okara, alsoproviding a matrix of high nutritional value as vehicle of L. plantarum CIDCA 83114, with promising applications in thedevelopment of novel functional foods and feeds.