Use of Ultra High Pressure Homogenization for Rice based beverage Stabilization

Plant-based or non-dairy milk alternative is the fast growing segment in newer food product development category of functional and specialty beverage across the globe. Nowadays, cow milk allergy, lactose intolerance, calorie concern and prevalence of hypercholesterolemia, more preference to vegan diets has influenced consumers towards choosing cow milk alternatives. Plant-based milk alternatives are a rising trend, which can serve as an inexpensive alternate to poor economic group of developing countries and in places, where cow’s milk supply is insufficient. Among alternatives, rice milk represent a source of biocompounds such as phytosterols, especially ß-sitosterol and γ-oryzanol resulting in cholesterol and hypertension decrease anti-diabetic, anti-inflammatory, antioxidative effects. Since these kind of beverage are characterized by high pH and great nutrient availability, they represent a substrate for the growth of spoiling and pathogenic microorganisms. For this, they are generally treated at very high temperature resulting in a loss of nutrients, vitamins and overall quality. New and advanced non-thermal processing technologies such as ultra high pressure homogenization, pulsed electric field processing are being researched for tackling the problems related to increase of shelf life, emulsion stability, nutritional completeness and sensory acceptability of the final product instead or in combination with traditional thermal treatments. Thus, principal aim of this research was to evaluate the potential of Ultra High Pressure Homogenization performed at 200 MPa for 1 and 3 cycles and in combination with different product inlet temperatures (25, 50, 60 and 70°C) to inactivate some pathogenic species (E. coli, Staphylococcus aureus, L. monocytogenes and Bacillus cereus used as spores), deliberately inoculated in raw rice based milk at level of 3 log cfu/ml. The ability of the target microorganisms to recover in the treated product during the storage at 25°C was also evaluated. The data obtained underlined as E. coli was more sensitive than Gram positive bacteria to the hyberbaric treatments performed, resulting under the detection limit in all the tested combinations. Moreover, this pathogen was able to recover only in products with inlet temperature of 25 and 50 °C and treated at 200 MPa just for 1 cycle. L. monocytogenes and Staphylococcus aureus were found under the detection limit in all the combinations of inlet temperature and pressure applied but they were able to recover during the product storage with the exception of L. monocytogenes inoculated in rice based milk having inlet temperature of 70°C (independently on the pressure applied). Indeed, the data have confirmed the great barotollerance of the spores of B. cereus used in this research. The results of the present investigation can confirm that the application of tailor-made treatments based on calibrated product inlet temperatures and ultra high pressure homogenization seems to be a promising alternative for the stabilization of this kind of product, generally reached at industrial levelwith severe high temperature treatments but with significant loss of bio-compounds important for human health.