Impact of pulsed electric field treated milk on quality of paneer and khoa

Abstract

The present work was undertaken to investigate the feasibility of pre-treatment of raw milk with Pulse Electric Field (PEF) treatment before its entry into the processing chain. A custom-designed and fabricated PEF applicator was used for the non-thermal treatment protocol. Raw milk was treated under three treatment protocols, viz., conventionally heat treatment (CHT), PEF treated milk subjected to conventional heat treatment (PT-CHT) and PEF treatment (PT). For the PT protocol, milk was subjected to high voltage (55 kV) square wave of pulse width 900 µs, for 100 s at a frequency of 90 Hz. The treated milk was then converted to two popular products, namely and paneer and khoa, which were evaluated for its physico-chemical, microbiological, sensory quality and shelf stability. Since khoa is a heat desiccated product, it was evaluated only against PT-CHT and CHT treatments. It was observed that PT treatment resulted in paneer with softer body with higher whiteness index, compared to other experimental samples. The PT treatment did not affect the product acceptability and the product had a shelf stability of 12 days under refrigeration, as against 16 days for CHT and PT-CHT treatment. The treatment protocols for milk did not significantly affect the quality and shelf life of khoa. Thus, there is wide future scope to used pulsed electric fields treatment synergistically with conventional heat treatment for inactivation of microorganisms, with better retention of nutritional and physical properties of product which has potential to save considerable amount of energy and time during processing of product.