Optimization of High-pressure Processing Parameters for Microbial Load Reduction in Young Coconut Water Using Response Surface Methodology

Abstract

This study investigated the effect of high-pressure processing (HPP) on the microbial load of young coconut water and optimized the processing parameters using Central Composite Design (CCD) and Response Surface Methodology (RSM). Young coconut water was treated at different pressure levels (300–600 MPa) and holding times (3–6 minutes). The microbiological analyses included Total Plate Count (TPC), Yeast and Mould, Coliform, Escherichia coli, Psychrophilic Bacteria and Staphylococcus aureus. A second-order polynomial response surface model was developed to describe the relationship between pressure, holding time, and microbial reduction. The model showed good prediction accuracy, with a high coefficient of determination (R² = 0.9914) and a non-significant lack-of-fit, indicating its adequacy in predicting microbial behaviour under HPP. The results showed that treatments above 450 MPa effectively reduced all microbial counts to undetectable levels (<1 log CFU/ml), while lower pressures (300 MPa) resulted in measurable TPC values. Optimization using the response surface model indicated that the optimum condition for microbial inactivation was 450 MPa for 3 minutes, achieving a desirability value of 1.0. Pressure was identified as the dominant factor influencing microbial reduction, whereas holding time had a lesser effect. These results indicate that HPP can effectively prolong the shelf life of young coconut water while ensuring microbial safety and product freshness. The developed model can be used  as a predictive tool for industrial-scale processing, highlighting the potential of HPP as a non-thermal preservation method to maintain the natural characteristics of young coconut water.