Protective effect of a cross‐linked starch by extrusion on the survival of <i>Bifidobacterium breve ATCC 15700 in yogurt</i>
Beneranda Murúa‐Pagola, Ana Laura Castro‐Becerra, Lucía Abadía‐García, Eduardo Castaño‐Tostado, Silvia L. Amaya‐Llano
Abstract
The protective effect of microencapsulation on the survival of Bifidobacterium breve 15,700 within polymeric matrices of high-amylose starch, cross-linked by extrusion and the conventional method in a slurry, blended with different ratios of whey protein concentrate (WPC), was evaluated. Assessments were carried out during microencapsulation by spray drying, during 28 day storage at 4°C in yogurt, and after exposure to simulated gastrointestinal conditions (SGC) at 14 day storage. The initial count of probiotic cells in yogurt increased during fermentation. Microencapsulated bacteria showed greater survival rates throughout storage time and after exposure to SGC than free cells. Increase of pH caused probiotic populations to decline, being the free cells the most affected. Cross-linked starches protected the cells to a similar extent as WPC when 10% w/w of this biopolymer was added. These results demonstrate that chemically cross-linked starches can be used successfully as encapsulating agents enhancing the probiotic survival under stressful conditions. Practical Applications The low viability of probiotic bacteria during processing in fermented foods and the adverse effects on sensorial properties of the final products due to over fermentation can be improved with the use of modified starch as wall material in the microencapsulation process by spray drying. The use of microencapsulated probiotic in a cross-linked starch enhances the addition to foods and the stability of probiotics compared with nonencapsulated bacteria.