Process optimization for in-line production of Rabri

Scraped surface heat exchanger (SSHE) was integrated with conical process vat (CPV) for in-line production of rabri. Response surface methodology was applied to optimize the process parameters on the basis of sensory score, chromatic and textural attributes. The four factors considered for optimization were initial concentration of milk in SSHE, final concentration of milk in CPV, ratio of clotted cream layer (CCL) to sweetened concentrated milk (SCM) and steam pressure of CPV during removal of CCL. Optimum parameters predicted for rabri production were initial concentration of milk to 30% total solids (TS) in SSHE, final concentration of milk to 40% TS in CPV before sugar addition, 0.167 CCL/SCM ratio and 0.8 kg/cm² steam pressure of CPV during removal of CCL. The observed values for flavour, body and texture, colour and appearance, overall acceptability, firmness, L*, a* and b* were 7.97, 7.93, 8.23, 8.067, 0.3540, 75.907, 01.14 and 16.3197 respectively.