Kinetics of HMF Formation during Storage of InstantKheerMix Powder and Development of a Shelf-Life Prediction Model

Abstract

Kheer is one of the most widely consumed traditional dairy products of Southeast Asian nations including India. Because of its poor shelf life, which hinders its commercialization and large-scale industrial production, product is confined to domestic kitchens and small-scale manufacturers. A shelf-stable dry mix was produced by using spray-drying technology with an aim to develop a convenient formulation for the traditional kheer. Instant kheer mix (IKM) powder could be easily reconstituted into kheer. The shelf life of IKM powder stored at 30, 37 and 45C was determined. Various physicochemical changes in kheer mix powder were monitored during storage and their effects on sensory properties of reconstituted kheer were studied and correlated. The change in color of IKM powder was found to be a zero-order reaction. The activation energy (Ea), Arrhenius constant and Q10 value for the reaction were 106.50 kJ/mol, 9.846 × 1,017 M/wk and 3.8, respectively. The total and free hydroxymethylfurfural (HMF) formation during storage was found to increase and sensory scores found to decrease during storage. In fresh kheer mix powder, the average value recorded was 5.0 µmol/L, which increased to 21.74 µmol/L after 24 weeks of storage at 30C. At 37 and 45C, the total HMF content increased to 30.4 and 56.3 µmol/L after respective storage durations of 16 and 8 weeks. These changes could be described well with first-order reaction kinetics. The rates of these reactions were highly temperature-dependent, the rates being higher at high temperature. The Ea and other activation parameters such as enthalpy, entropy and free energy of activation for these reactions were determined. The interrelationships between sensory and HMF changes were established. The sensory color was negatively correlated with absorbance and also with increase in HMF values. The shelf-life prediction model, which was developed based on the kinetic constants and the relationship between sensory and chemical parameters, could be useful in predicting the shelf life of kheer mix powder. Potential shelf life of kheer mix powder was found to be 92 weeks at 37C, which is comparable with most spray-dried powders. PRACTICAL APPLICATIONS About 50% of the milk produced in India (117.0 million tons) is converted into traditional dairy foods. Traditional dairy foods include cereal-based dairy desserts, which are confined to domestic kitchens because of lack of technological processes for their large-scale manufacture. Packaging of these products is almost nonexistent. Market for such products is estimated to be about INR 50,000 crore (US$ 10.29 billion). Most of these products are consumed locally as they suffer from poor shelf life. Recent focus is on developing new and innovative processes for converting these traditional dairy foods into convenient formulations so that shelf life is enhanced and there is an ease of consumption. Development of a spray-dried process for large-scale manufacture of instant kheer mix with a potential shelf life of more than 92 weeks at ambient temperature could result in product diversification, export promotion and value addition for the food and dairy industry.