The use of encapsulated starter culture for improving the quality of the heat treated sausage like product

The main target in heat treatment during sucuk production is elimination of the foodborne pathogen bacteria at approximately 68-70°C for 15-30 min. However, problems in physical, chemical and sensory quality as well as product safety may arise during production and storage due to the significant reduction of desirable bacteria. Encapsulation thus may protect the viability of starter cultures from heat treatment. Studies using free or encapsulated starter cultures in heat treated sucuks are still scarce. In this context, the purpose of the present study was to evaluate morphological properties, survival rate and release behavior of starter cultures of L. plantarum and S. xylosus, microencapsulated using an emulsion method with the alginate-starch mixture, and also to monitor the effects of addition of these encapsulated starter cultures on physicochemical and microbiological characteristics of heat treated and fermented sucuks. Analyses were carried out at days 0 (befor production), 14 (after production), 30 and 45 during refrigerated storage (4°C).Moisture, aw, residual nitrite, TBA and pH values of fermented sucuks were lower than those of heat treated samples. Encapsulated starter cultures did not create significant differences on physicochemical properties of fermented sucuk at the end of manufacturing period (14 days), except for TBA and residual nitrite value. However moisture, aw, residual nitrite value and titratable acidity value were affected with encapsulated starter cultures in heat treated sucuk. Compared to initial counts (7 log CFU/g sucuk), reduction rates of Lactic acid bacteria in heat treated samples at day 0 were 1.28 log unit for encapsulated sample and 4.81 log unit for free sample, while the reduction for Micrococcus-Staphylococcus in encapsulated and free samples were determined as 1.20 log unit and 3.37 log unit, respectively. The highest number of viable cell was determined in the sample containing encapsulated starter culture. Biogenic amines such as, putrescine, histamine, cadaverine, spermidine, tyramine and spermine were detected in all samples, but in higher quantity in fermented sucuks. Compared to free starter cultures inoculated sucuks, encapsulated starter cultures inoculated ones have lower level of tyramine (87.99 and 70.15 mg/kgDW, respectively) and spermine (93.45 and 82.06 mg/kg DW).The number and quantity of volatile compounds was higher in fermented sucuks than those of heat treated sucuks ones. All the volatile compounds except esters were less reduced by utilization of encapsulated starter cultures compared to free starter culture inoculation in the production of heat treated sucuks. There are no significant changes in textural and sensorial attributes between the free and encapsulated starter culture inoculated sucuks after 45 days storage.In conclusion, microencapsulation of starter cultures was investigated as an emerging technique to regulate fermentation processes and to maintain specific product characteristics of fermented and heat treated sucuks. The results revealed that alginate-starch based encapsulation technique enhanced the stability of microcapsules containing starter cultures in adverse conditions. Utilization of encapsulated starter cultures in the production of heat treated sucuks ensured their viability before, during and after production (both fermentation and heat treatment), and resulted in lower residual nitrite content, higher acidity generation and volatile compounds in comparison to the free cultures, which could offer health and safety benefits for the ultimate product.