Phytochemicals preservation in strawberry as affected by pH modulation.

Area of Science:

• Food Science
• Food Chemistry
• Nutritional Science

Background:

• Strawberry purées are common food ingredients, requiring understanding of polyphenol stability during processing and storage.
• Polyphenols, like anthocyanins and flavonoids, contribute to strawberry's health benefits and sensory properties.
• pH modulation is a key factor influencing polyphenol stability in food matrices.

Purpose of the Study:

• To evaluate the impact of pH and storage temperature on strawberry polyphenol stability over 90 days.
• To determine optimal conditions for preserving total antioxidant activity, phenolics, and specific compounds like anthocyanins.
• To model the degradation kinetics of key polyphenols under different storage scenarios.

Main Methods:

• Strawberry purées were adjusted to various pH levels (2.5, 3.0, 4.5) and stored at 4°C and 23°C for 90 days.
• Total antioxidant activity and total phenolics content were measured over time.
• Concentrations of specific polyphenols, including (-)-epigallocatechin gallate, quercetin-3-glucoside, ellagic acid, and various anthocyanins, were quantified.
• Degradation kinetics were modeled using a first-order model.

Main Results:

• Total antioxidant activity and phenolics content decreased over time, following a first-order kinetic model.
• pH 4.5 led to significant decreases in (-)-epigallocatechin gallate and quercetin-3-glucoside at both temperatures.
• Ellagic acid increased under acidic conditions (pH 2.5 and 3.0), particularly at 23°C.
• Anthocyanin degradation followed a first-order model, with the slowest degradation rate observed at pH 2.5.

Conclusions:

• Lower storage temperatures (4°C) and acidic pH (2.5) are optimal for preserving strawberry polyphenols, including anthocyanins, over 90 days.
• Understanding these degradation kinetics is vital for maintaining the quality and health benefits of pasteurized strawberry products.
• Specific polyphenol responses varied, with some increasing (ellagic acid) and others decreasing under different pH and temperature conditions.