Physicochemical, and microbiological characteristics of probiotic dark chocolate bar sweetened with palm sugar and coconut sugar

Abstract

Dark chocolate is considered a nutritious food due to its high polyphenol and antioxidant activity. The improvement of chocolate functionality can be conducted by enriching it with probiotics. Replacement of sucrose in probiotics-enriched chocolate with palm or coconut sugar serves as a probiotic protective agent and increases its functional value. The addition of probiotics and sugar replacement will change the physical, chemical and microbiological properties of dark chocolate products. This research aimed to investigate the physical, chemical and microbiological characteristics of probiotic dark chocolate with sucrose replacement by coconut sugar and palm sugar. The viscosity, colour, melting profile and surface microstructure were investigated for physical properties of probiotic dark chocolate. Total phenolic content was measured by Folin-Ciocalteu method, and the antioxidant activity was quantified by the DPPH radical method. Total lactic acid bacteria were evaluated for microbiological properties of chocolates. As a reference, probiotics enriched dark chocolate with sucrose were also studied. The results showed that the viscosity of all the samples was significantly different, and chocolate sweetened with coconut sugar was the most viscous. Based on the DSC profile, chocolate sweetened with sucrose had a lower melting temperature than chocolate sweetened with coconut and palm sugar. The antioxidant activity of chocolate sweetened with palm sugar was significantly higher than that of chocolate sweetened with coconut sugar and reference. Probiotic dark chocolate sweetened with coconut sugar and palm sugar had significantly higher total polyphenols than reference. Sugar replacement did not significantly influence the calorie value, but palm sugar was proven in reducing the calorie of the probiotic dark chocolate. Dark chocolate provided suitable protection in fulfilled adequate viability for being claimed as a probiotic food, i.e., 6.88, 6.94, 7.16 log CFU/g respectively. Microscopy visualization showed that sugar agglomeration happened in both probiotic dark chocolates sweetened with coconut sugar and palm sugar. In general, the replacement of sucrose with palm and coconut sugar slightly increases the total phenolic content and antioxidant activity of probiotics-enriched dark chocolate.