Optimization of Infrared Postharvest Treatment of Barhi Dates Using Response Surface Methodology (RSM)

Abstract

Barhi dates are widely consumed at Khalal maturity stage and preserving the freshness quality of Barhi at this stage is a challenging task as this period is short and the fruits are more perishable. In this study, response surface methodology (RSM) was applied to optimize the infrared (IR) treatment and storage conditions for preserving the physicochemical, microbial, and bioactive attributes of fresh Barhi dates. The effect of four factors, IR temperature (50, 70, 90, and 110 °C), IR time (1, 2, 3, and 4 min), storage temperature (1, 5, 15, and 25 °C), and storage time (1, 6, 11, 16, and 21 days), on the responses of total soluble solids (TSS), hardness, total color change (ΔE), total viable count (TVC), total phenolic content (TPC), antioxidant activity (DPPH), and glucose content were evaluated following central composite design (CCD). IR temperature, IR time, storage temperature, and storage time significantly affected the physical, microbial, and bioactive attributes of Barhi dates. The optimal conditions for minimizing the physical changes and microbial load and maximizing the bioactive attributes were IR temperature of 50 °C, IR time of 1.2 min, storage temperature of 1 °C, and storage time of 20 days. At the optimum conditions, the values of TSS, hardness, ΔE, TVC, TPC, DPPH, and glucose were 37.22%, 70.17 N, 11.12, 2.9 log CFU/g, 36.1 mg GAE/g, 65.31%, and 25.38 mg/g, respectively and these values were similar to predicted values. In conclusion, this study identified the ideal IR treatment and storage conditions for maintaining the overall quality attributes of Barhi dates during prolonged storage.

Extending the Shelf Life of Fresh Khalal Barhi Dates via an Optimized Postharvest Ultrasonic Treatment

“…The high coefficients of determination (R 2 ) were observed for TSS, firmness, ∆E, TVC, TPC, DPPH, glucose, and fructose, which were ranged from 0.925 to 0.992, suggesting that the applied quadratic polynomial models (Equation (9)) contributed to more than 92% of the total variability of traits. Similar observations were recently reported for Barhi dates treated with infrared at different doses and duration and storage at different temperature and times [ 15 ]. Comparable results of coefficients of determination (R 2 ), predicted R 2 and adjusted R 2 indicate a good statistical model [ 16 ].…”

“…Comparable results of coefficients of determination (R 2 ), predicted R 2 and adjusted R 2 indicate a good statistical model [ 16 ]. The current results showed that adjusted R 2 of the assessed attributes were in the range of 0.871 to 0.958, which was comparable to that of R 2 (0.925 to 0.992) indicating high significance of the applied model that is similar to our recent observations on RSM model used for optimizing infrared treatment of Barhi dates [ 15 ]. In addition, the coefficient results also indicated high correlations between predicted and actual values of TPC, TSS, firmness, DPPH, ∆E, TVC, glucose, and fructose because the coefficient values (R 2 and adjusted R 2 ) were near to one [ 16 , 17 ].…”

“…Postharvest processing circumstances are very important issues that affect the storability and quality attributes of Barhi dates, which are mostly traded and consumed at a very perishable Khalal maturity stage [ 14 ]. At this stage, the freshness and shelf life of Barhi dates are greatly influenced by improper postharvest processing conditions, which might accelerate the senescence, ripening, respiration, and microbial spoilage processes [ 15 ]. To overcome such problems, the present study was conducted to evaluate the influence of ultrasound usage and subsequent storage circumstances on the physicochemical quality aspects of Barhi dates and to optimize the ultrasound usage and storage environments using the response surface methodology (RSM) model.…”

“…Similar observations on the reduction in kiwi fruit firmness following increased US intensity and temperature and attributed that to the mechanical effects of ultrasound [ 23 ]. The increase in firmness following increased storage temperature and US treatment time could be attributed to the evaporation of moisture content from the surface layers of the dates [ 15 , 24 ].…”

“…In addition, prolonged exposure of Barhi dates to US could also induce cavitation and affect the cell wall stability, thereby leading to a reduction in firmness [ 20 ]. The increase in firmness following the increase in US treatment and storing environments is possibly owing to the evaporation of water from the surface of Barhi dates making the surface harder and firmer [ 15 , 24 ].…”