Changes in quality attributes throughout storage of strawberry juice processed by high-intensity pulsed electric fields or heat treatments (original) (raw)
Related papers
Food Chemistry, 2009
The effects of high-intensity pulsed electric fields (HIPEF) processing (35 kV/cm for 1700 ls using pulses of 4 ls at 100 Hz in bipolar mode) and thermal treatments (90°C for 30 s or 60 s) on lipoxygenase (LOX) and b-glucosidase (b-GLUC) activities as well as on the production of volatile compounds were assessed in strawberry juice for 56 days of storage. HIPEF-treated juice kept higher residual LOX activity than heattreated juices during the first 28 days of storage. Moreover, b-GLUC increased its initial activity just after HIPEF processing. The concentration of DMHF in HIPEF-processed strawberry juice was above those of untreated and heat-treated juices during the first 14 days of storage. On the other hand, concentrations of ethyl butanoate and 1-butanol obtained after HIPEF processing were better maintained than after thermal processing. However, thermally-treated samples showed an increase in the amount of 1-butanol beyond day 35, causing an unpleasant flavour to the product. Thus, flavour stability in HIPEF-processed strawberry juice was greater than in thermally-treated samples during storage.
Food Control, 2011
A response surface methodology was used to determine the combined effect of HIPEF critical processing conditions on vitamin C, anthocyanins and antioxidant capacity of strawberry juice. Keeping constant the electric field strength at 35 kV/cm and the treatment time at 1000 ms, the treatments were set at frequencies from 50 to 250 Hz, pulse width from 1 to 7 ms using monopolar or bipolar mode. A second order response function covering the whole range of experimental conditions was obtained for each healthrelated compound. Strawberry juice antioxidant potential was affected linearly by frequency, pulse width and pulse polarity. The quadratic term of frequency and the combined effect of frequency and pulse width were also significant. HIPEF treatments conducted at 232 Hz with bipolar pulses of 1 ms led to strawberry juices with the greatest presence of health-related compounds. The evaluation of the HIPEF critical parameters influence on health-related compounds can contribute to achieve optimal processing conditions to obtain strawberry juices with high antioxidant potential.
Food Engineering Reviews, 2020
Understanding the efficacy of viable emerging technologies in preserving overall quality attributes and antioxidant characteristics of fruit juices is of great interest. This study aimed to evaluate the effect of high pressure (HP), ultrasound (US), and pulsed electric fields (PEF) processes on natural microbiota inactivation, as well as changes in physicochemical attributes and phytochemical content of strawberry juice (SJ). HP at 300 MPa (1 min), US at 55°C (3 min) and 517.1 mW/mL acoustic energy density, and PEF at 35 kV/cm (27 μs) using monopolar square pulses with 2 μs pulse width were applied, and then compared with a conventional thermal pasteurization treatment (72°C, 15 s). The nonthermal processes were equivalent in terms of Escherichia coli (E. coli) inactivation since the selected processing conditions led to almost identical inactivation level (at least 5-log) of inoculated E. coli. The current study analyzes why these equivalent processes had different effect on SJ quality. All treatments significantly reduced the initial natural microbiota (i.e., total mesophilic aerobic bacteria and yeast-molds) below 2 log CFU/mL. No significant changes were observed on the total soluble solid content (7.83-8.00°Brix), titratable acidity (0.79-0.84 g/100 mL), and pH (3.45-3.50; except in sonication) between SJ processed samples and the untreated ones (p > 0.05). HPP and PEF significantly promoted higher retention of total phenolic content (TPC) and radical scavenging activity (RSA) than thermal pasteurization, and significantly enhanced total anthocyanin content (TAC) compared with unprocessed SJ. HPP and PEF increased the TPC (4-5%), RSA (18-19%), and TAC (15-17%) in comparison with unprocessed SJ. Multivariate data analysis tools, i.e., principal component analysis (PCA) and hierarchical cluster analysis (HCA), were successfully applied for discrimination and classification of SJ samples based on the similarities or differences among physicochemical and phytochemical characteristics. PCA and HCA indicated that HPP-and PEF-treated samples had similar enhanced properties in terms of phytochemical content and were superior to sonicated, thermally pasteurized, and unprocessed samples. The multivariate data analysis methods were very useful to compare and classify SJ quality characteristics as a function of the processing technology. This study demonstrated that the application of the equivalent processing approach may reveal new opportunities to produce equivalent or even enhanced quality fruit juices.
Journal of Food Protection, 2006
Pulsed electric field treatment has been claimed to produce more acceptable chilled citrus juices than those obtained by conventional thermal treatment. The pectin methylesterase activity and the acceptability of nine juices obtained from Clementine mandarins, Valencia oranges, and Ortanique fruits (hybrid of mandarin and orange), untreated, pasteurized (85°C for 10 s), and treated by pulsed electric fields (25 kV/cm for 330 μs), were evaluated. The treatments, selected to reach a similar level of pectin methylesterase inactivation, produced juices that did not differ in acceptability from each other for the three varieties and in all cases were less acceptable than the untreated juice.
Food Control, 2008
High Intensity Pulsed Electric Field (HIPEF) is one of the nonthermal minimal processing technologies interesting for scientists and food industry as a new, alternative (preservation) process for liquid food. We have evaluated the effect on color, browning and hydroxymethylfurfural (HMF) of a pasteurized orange juice and the same orange juice treated by HIPEF, during 7 weeks stored in refrigeration at 2°C and 10°C. Pasteurized orange juice presents greater yellow tendency (b * ) and less red tendency (a * ) than the untreated orange juice, while HIPEF orange juice presents a coloration more similar to the untreated orange juice. Color variations (DE) during storage are greater in orange juice pasteurized than in HIPEF treated orange juice. Non-thermal treated orange juice has less nonenzymatic browning than the pasteurized one. There is a significant increase in this parameter from the fourth week of storage in all the juices stored at 10°C, while in the ones stored at 2°C the browning index values are maintained during more time. There are no significant variations in the HMF content of the juices pasteurized or treated by HIPEF respect the untreated orange juice. During refrigerated storage, HMF is always below the maximum values established.
Journal of Food Process Engineering, 2016
Effects of pulsed electric fields (PEF) processing on physical properties, bioactive compounds, and formations of furfural and hydroxylmethylfurfural (HMF) were determined for apple juice. A central composite design to determine the optimal number and order of experimental runs and the best-fit multiple nonlinear regression (BF-MNLR) models to quantify and predict rates of change in the response variables as a function of the PEF processing were used. No significant difference was detected between the control and PEF-treated apple juice in terms of physical properties, organic acids, and polyphenols of (2)-epicatechin, caffeic acid, p-coumaric acid, ferrulic acid, quercetin, and gallic acid. The highest predictive power (R 2 pred) belonged to a* (88%), (1)-catechin (90.7%), and HMF (93.8%). Except for chlorogenic acid, no significant decrease was detected in the initial concentrations of the bioactive compounds. PEF processing provided retention of quality attributes and bioactive compounds without significant formation of furfural and HMF. Practical applications Heat processing causes degradation of bioactive compounds, changes in physical properties, and formation of undesirable compounds in apple juice; however, PEF processing provided the preservation of most bioactive compounds without significant changes in physical properties. Thus, findings in this study revealed that PEF processing is a viable option for fruit juice industry, especially, for apple juice pasteurization. 1 | INTRODUCTION The consumption of apple juice, one of the most popular fruit crops, reached 76 million tons globally and 15 million tons in Europe in 2012 (FAOSTAT, 2013). Apple juice plays an important role in human nutrition owing to its high level of antioxidants, phenols or phenolic compounds that may defend humans against free radical damage, thus reducing the incidences of coronary heart disease and cancer (Lee, Hwang, & Ha, 2003). Heat processing is the most common processing method commercially applied to fruit juices (Aadil et al., 2015). However, the deterioration of juice quality, flavoring agents, and compounds with antioxidant properties during the heat processing have oriented consumer preferences towards minimally processed fresh-like juices with enhanced nutritional and sensory properties. Thus, many studies have focused on novel nonthermal pasteurization technologies of fruit juices including pulsed electric fields (PEF) with different magnitudes of electric field strength (Evrendilek & Varzakas, 2015). There are numerous studies about effects of PEF on bioactive compounds, enzyme and microbial inactivation, physical and sensory properties, and shelf life extension (
LWT-Food Science and …, 2009
Novel non-thermal processing technologies such as high-intensity pulsed electric field (HIPEF) treatments may be applied to pasteurize plant-based liquid foods as an alternative to conventional heat treatments. In recent years, there has been an increasing interest in HIPEF as a way of preserving and extending the shelf-life of liquid products without the quality damage caused by heat treatments. However, less attention has been paid to the effects of HIPEF on minor constituents of these products, namely bioactive compounds. This review is a state-of-the-art update on the effects of HIPEF treatments on healthrelated compounds in plants of the Mediterranean diet such as fruit juices, and Spanish gazpacho. The relevance of HIPEFprocessing parameters on retaining plant-based bioactive compounds will be discussed.
Food and Bioproducts Processing, 2016
Processing of orange juice by pulsed electric fields (PEF) and heat treatments was carried out to determine the quality variables during storage of 180 days at 4 • C. Depending on the magnitude of applied electric field strength (13.82-25.26 kV cm −1), energy (10.89-51.32 J), in comparison with heat treatment (90 • C for 10 and 20 s); significant changes in pH, titration acidity, total dry matter, and browning index were found during the storage period. With no significant change in shelf-life period, the PEF processing better preserved orange juice quality than did the heat processing. Ascorbic acid content peaked with PEF-treated orange juice under the electric field strength of 17 kV cm −1 , the treatment time of 1034 s, and the energy of 17.37 J through which no significant degradation occurred during the storage with the longest half-life (1112 days). Although ascorbic acid retention of the most of the PEF processed samples was higher than that of the heat processed ones; samples processed by 10.89, 12.70 and 29.57 J energies resulted in lower ascorbic acid content than did the heat processing (90 • C for 20 s). Except for the samples treated by 43.99 and 51.32 J energies on 180th day, the PEF processing led to no hydroxyl methyl furfural formation during and at the end of the storage, unlike the heat treatment.
Lwt - Food Science and Technology, 2010
A response surface methodology was used to determine the combined effect of HIPEF critical processing conditions on vitamin C, anthocyanins and antioxidant capacity of strawberry juice. Keeping constant the electric field strength at 35 kV/cm and the treatment time at 1000 ms, the treatments were set at frequencies from 50 to 250 Hz, pulse width from 1 to 7 ms using monopolar or bipolar mode. A second order response function covering the whole range of experimental conditions was obtained for each healthrelated compound. Strawberry juice antioxidant potential was affected linearly by frequency, pulse width and pulse polarity. The quadratic term of frequency and the combined effect of frequency and pulse width were also significant. HIPEF treatments conducted at 232 Hz with bipolar pulses of 1 ms led to strawberry juices with the greatest presence of health-related compounds. The evaluation of the HIPEF critical parameters influence on health-related compounds can contribute to achieve optimal processing conditions to obtain strawberry juices with high antioxidant potential.
Foods
Novel pulsed electric field (PEF) process conditions at moderate electric field strength and long pulse duration have recently been established to obtain microbial inactivation. In this study, the effect of these PEF conditions (E = 0.9 and 2.7 kV/cm, with pulse duration 1000 µs) at variable maximum temperatures was evaluated on quality attributes of freshly squeezed orange juice. Results were compared to orange juice that received no treatment or a mild or severe thermal pasteurization treatment. No differences for pH and soluble solids were found after application of any treatment, and only small differences were observed for color and vitamin C content (ascorbic acid and dehydroascorbic acid) after processing, mainly for conditions applied at higher temperature. Variations in the maximum temperatures of the PEF and thermal processes led to differences in flavor compounds and the remaining activity of pectinmethylesterase (PME). At PEF conditions with a maximum temperature of 78 °...