The Application and Optimization of HIPEF Technology in the Processing of Juice from Strawberries Harvested at Two Stages of Ripeness

Abstract

The aim of this study was to investigate the influence of high intensity pulsed electric field (HIPEF) technology on the stability of total phenols, anthocyanins, hydroxycinnamic acids, flavonols, and condensed tannins in strawberry juices (Fragaria x ananassa Duch. cv. ‘Albion’) with different ripening stages (75% and 100%) and stored at +4 °C for 7 days. The HIPEF parameters studied were: (i) electric field strength (40 and 50 kV cm−1), (ii) frequency (100 and 200 Hz), and (iii) treatment duration (3 and 6 min). Of the HIPEF parameters studied, electric field strength and frequency had a statistically significant effect on the content of all phenolic compounds. Treatment duration showed no statistically significant effects on phenolic compounds except for flavonols and condensed tannins. Storage had a positive effect on the stability of most of the phenolic compounds, with the exception of flavonols. Optimization of HIPEF processing showed that strawberry samples at both ripeness levels were suitable for HIPEF treatment to obtain functional fruit juices with a high content of polyphenols.

A Chemometric Investigation on the Functional Potential in High Power Ultrasound (HPU) Processed Strawberry Juice Made from Fruits Harvested at two Stages of Ripeness

“…The levels of all studied bioactive compounds in the control samples, except for total phenolic compounds and FL, were significantly higher (p ≤ 0.01) in juices made from 100% ripe fruit than those of 75% ripeness, this is largely consistent with our previous findings [37]. As ripeness increased, TPC decreased in control samples, which is consistent with other literature [44].…”

“…Storage positively influenced the contents of HCA and FL in control samples, while the contents of ANT decreased (Table 3). The value of HCA was 6.2% higher after 7 days of storage than after 0 days, which is in agreement with other literature reports [37,38]. The previous study confirmed that total and individual anthocyanins were degraded during storage according to first-order reaction kinetics, and the rate was strongly dependent on temperature [46].…”

“…Since HPU technology has not yet been used to process fruit of different ripeness levels, it is unknown whether this technology would be suitable for processing strawberry juices from two ripeness levels. A recent study applying High Intensity Pulsed Electric Field (HIPEF) has shown that this technology is suitable for processing strawberry juices from different ripening stages, as it improves the stability of bioactive compounds during shelf life [37].…”

High-Power Ultrasound (HPU) and Pulsed Electric Field (PEF) in the Hurdle Concept for the Preservation of Antioxidant Bioactive Compounds in Strawberry Juice—A Chemometric Evaluation—Part II

“…In order to better understand the synergetic relationships between the two technologies, the influence of both technologies on the quality of the juices tested was investigated. The process parameters were previously optimized for both HPU and PEF technologies [11], so the influence of treatment duration was investigated in this study.…”

“…Recently, pulsed electric field (PEF) and high-power ultrasound (HPU) technologies have shown promising results in the processing of fruit juices to obtain stable and biologically valuable functional products [10][11][12]. PEF technology is characterized by the inactivation of microorganisms and enzymes, which can be a substitute to thermal pasteurization [13].…”