Extensão da vida útil de morangos inteiros e minimamente processados tratados com infusão a vácuo de pectinametillesterase e lactato de cálcio

Abstract

The demand for healthy foods has led to an increase in the consumption of fresh fruits, such as strawberries. However, strawberries are a highly perishable fruit with a limited shelf-life due to rapid softening and deterioration, which are intensified in minimally processed (MP) products. Softening and loss of firmness are crucial parameters for consumer acceptance. The aim of this study was to evaluate the effectiveness of the combined use of vacuum infusion (IV), calcium lactate (LCa), and pectin methylesterase (PME) in maintaining firmness, cell integrity, and post-harvest quality of whole (I) and minimally processed (MP) strawberries. The strawberries (I and MP) were subjected to vacuum infusion with water (W), PME (10 IU), LCa (1%), and LCa+PME, with a control group (C) without infusion. Firmness, fresh mass loss, anthocyanin, color, soluble solids content (SSC), total acidity (TA), SSC/TA ratio, pH, visible deterioration and damage, visual quality, galacturonic acid content, degree of methylation, electrolyte efflux, PME activity, and respiration were measured initially and every 3 days for 9 days of storage at 5°C for MP fruits and every 3 days for 12 days for whole fruits (I). The results demonstrate that the treatment with LCa+PME was effective in both presentation forms. In minimally processed strawberries (MP),vacuum infiltration of PME with calcium lactate increased firmness by 90.7% for LCa+PME and 119.8% for LCa on the third day, delayed weight loss to less than 0.8% in all treatments except the PME treatment, maintained freshness and anthocyanin content, reduced electrolyte efflux by 38% compared to the control, and decreased respiration rates to 134.92 and 135.62 mg.kg⁻¹.h⁻¹ CO₂ for LCa+PME and LCa, respectively, while the control reached 163.36 mg.kg⁻¹.h⁻¹ CO₂. Furthermore, it minimized fruit damage. For whole fruits (I), LCa + PME increased fruit firmness by 48% after 3 days of storage compared to fruits from the control treatment (W), maintaining it for up to 12 days of storage. This stability was attributed to the synergy of the treatment between LCa and exogenous PME, which increases free carboxylic groups, optimizing the formation of Ca-pectate cross-links, resulting in the stabilization of CSP (sodium carbonate soluble pectin). Additionally, treatments using calcium reduced electrolyte leakage by 22% and limited mass loss by approximately 2.7% for LCa + PME, resulting in better freshness and lower incidence of damage and contamination. LCa + PME significantly preserved color parameters (L*, C*) and extended shelf-life by at least 3 days. Thus, vacuum infusion of calcium lactate and PME is a promising technology capable of significantly extending the post-harvest quality and shelf-life of whole, minimally processed strawberries.