Equivalent processing for pasteurization of a pineapple juice-coconut milk blend by selected nonthermal technologies

Area of Science:

• Food Science and Technology
• Microbiology
• Food Engineering

Background:

• Ensuring food safety requires effective microbial inactivation while preserving quality attributes.
• Pineapple juice-coconut milk (PC) blends present unique challenges for preservation due to their composition and pH.
• Establishing equivalent processing conditions is crucial for comparing the efficacy of different non-thermal technologies.

Purpose of the Study:

• To identify equivalent processing conditions for achieving a 5-log reduction of Escherichia coli and Listeria innocua in PC blends.
• To compare the effectiveness of high-pressure processing (HPP), pulsed electric fields (PEF), and ultrasound (US) as standalone or combined preservation methods.
• To evaluate the impact of these equivalent conditions on key quality attributes of PC blends.

Main Methods:

• PC blends at pH 4 and 5, and coconut milk at pH 7, were treated with HPP (300-600 MPa), PEF (10-21 kV/cm), and US (120 µm amplitude).
• Treatments were applied alone or in combination with pH adjustment, nisin, and/or heat.
• Microbial reduction was assessed for E. coli and L. innocua, and quality attributes (total soluble solids, acidity, pH, viscosity, ascorbic acid, color) were measured.

Main Results:

• Equivalent conditions for a 5-log reduction of E. coli at pH 4 were determined for HPP (400 MPa, 1 min), PEF (21 kV/cm, 24 µs), and US (120 µm, 6 min).
• L. innocua required synergistic effects, with optimized conditions including nisin for HPP, PEF, and US treatments.
• No significant changes in total soluble solids, acidity, pH, or viscosity were observed under the identified equivalent conditions.
• High-pressure processing (HPP) showed superior performance in retaining ascorbic acid and minimizing color changes compared to PEF and US.

Conclusions:

• Equivalent processing conditions were successfully established for inactivating E. coli and L. innocua in PC blends using HPP, PEF, and US.
• HPP emerged as the most effective technology, preserving quality attributes like ascorbic acid and color better than PEF and US.
• The findings provide valuable insights for optimizing non-thermal processing strategies in the food industry, particularly for juice and milk-based beverages.