High Pressure Microfluidization: a Novel Strategy to Improve Stability and Structural Properties of Pearl Millet Drink.

Pearl millet (Pennisetum glaucum), a vital cereal crop widely cultivated in the arid and semi-arid regions due to its remarkable tolerance to drought, high temperature, and poor soil fertility. More prominently, these grains are rich in carbohydrates and high proportion of starch, which tends to sediment when the grain extract is prepared in liquid food forms. To address this stability issue, various processing techniques and additives have been explored, among which High-Pressure Microfluidization (HPMF), an efficient hydrothermal-mechanical method capable of inducing controlled structural modifications. Moreover, by employing this technique, the present study was primarily directed toward investigating the impact of HPMF on the physical stability of pearl millet extract, with emphasis on assessing its resistance to phase separation, sedimentation, and structural degradation during storage. Typically, the optimized malting conditions were standardized as soaking at 35 °C for 12 h, followed by sprouting at 30 °C for 2 days, and then drying at 48 °C for 8 h. Further, nisin was incorporated at three concentrations (10,25 and 50 ppm), extending its shelf life to 12 days. Subsequently, soy protein was added at 6, 8 and 10% levels, and the samples were subjected to microfluidization at four pressures viz., 10,000, 15,000, 20,000 and 25,000 psi (68.95, 103.43, 137.90 and 172.38 MPa) for one and five cycles. As a result, the combination of 8% soy protein with 25,000 psi (172.38 MPa) for five cycles yielded the lowest sedimentation rate, maintaining physical stability for 12 days. Meanwhile, the treated samples exhibited pH 7.0, titratable acidity 0.16, viscosity 26.32 and TSS 15 °Brix. Collectively, these findings confirmed that the synergistic application of HPMF and Soy Protein Isolate (SPI) fortification markedly enhances the stability of pearl millet extract, offering a promising strategy for formulating shelf-stable and value-added millet beverages/products. Overall, this approach offers promising potential for the development of shelf-stable, ready-to-drink millet-based beverages, catering to the growing demand for nutritious and sustainable plant-based alternatives.