Effects of high-pressure processing and conventional thermal processing on enzyme activities, antioxidant properties, and volatile metabolic profiling of “Phulae” pineapple purée

Abstract

This study investigated the effects of high-pressure processing (HPP) at 400 and 600 MPa (10 min, 25 °C) compared with conventional thermal processing (CTP; 10 min, 80 °C) on the quality of “Phulae” pineapple purée (Ananas comosus L. cv. Phulae). Untreated purée served as the control. HPP effectively preserved key quality parameters of the purée, including total soluble solids (13.5 °Brix) and color (L* 46.6–48.0; b* 21.3–22.0), with only slight deviations from the untreated samples (L* 49.4; b* 24.1). The vitamin C content was higher in the HPP-treated purée (216.9 mg kg⁻¹) than in the CTP-treated purée (167.0 mg kg⁻¹). The antioxidant capacity was enhanced in the HPP-treated purée, particularly with HPP at 400 MPa, with a total phenolic content of 73.8 g gallic acid equivalents/kg fresh weight (FW), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of 2.3 mmol Trolox equivalents (TE)/kg FW, and ferric reducing antioxidant power (FRAP) of 4.7 mmol ascorbic acid equivalents/kg FW. 2,2′-Azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activity was the highest in purée treated with HPP at 600 MPa (4.6 g Trolox equivalent antioxidant capacity/kg FW). HPP also preserved enzyme-related activities, including bromelain activity (3441.7–3733.3 casein digestion units/L) and hyaluronidase (HA) inhibition (78.8–79.9%). Moreover, nitric oxide (NO) radical inhibition was significantly reduced in CTP-treated purée, while HPP-treated samples retained higher inhibition levels (47.0 mmol TE per kg FW). Volatile compound analysis identified esters and terpenes, including their various subgroups, as the dominant contributors to the aroma profile. Based on principal component analysis, principal components 1 and 2 explained 60.4% and 25.3% of the total variance, respectively, accounting for a combined 85.7% of the variability in the dataset. HPP-treated purée clustered closely with the untreated purée, indicating a preserved aroma profile. These findings highlight that HPP is a promising non-thermal technique for maintaining the nutritional, functional, and sensory qualities, especially aroma, of fruit-based products.