Effect of Conching Process Parameters on Casson Viscosity of Emulsifier-Free Milk Chocolate

Milk chocolate is a type of chocolate composed of cocoa nibs, milk powder, sugar and cocoa butter. Generally, emulsifiers are commonly added to chocolates in order to modify their flow properties. Therefore, it is intriguing to explore the influence of conching process parameters on the viscosity of milk chocolate without emulsifiers. This paper aims to investigate the impact of various conching process parameters on the Casson viscosity of emulsifier-free milk chocolate. The effect of conching process parameters viz. conching temperature, conching time and rotation speed of the machine on the Casson viscosity of emulsifier-free milk chocolate was studied. The study was conducted at Food Processing Lab of KCAET, Tavanur, Kerala in the year 2022-2023. The Casson viscosity of the chocolate samples was determined using a controlled stress-strain rheometer. The results showed that Casson viscosity of emulsifier-free milk chocolate varied from 6.5 and 14.5 Pa.s and chocolate had shown a shear thinning behaviour. The study shows that Casson viscosity increased with decrease in conching temperature and conching time. Whereas increase in Casson viscosity was observed with increase in rotation speed of machine. The coefficient of determination (R2) for the regression model was 0.97 shows the significant effect of conching process parameters on Casson viscosity of emulsifier-free milk chocolate.