Quality assessment of Cantaloupe melon juice under ozone processing

Effect of ozone treatment on phenylpropanoid metabolism in harvested cantaloupes

Phenylpropanoid metabolism plays an important role in cantaloupe ripening and senescence, but the mechanism of ozone regulation on phenylpropanoid metabolism remains unclear. This study investigated how ozone treatment modulates the levels of secondary metabolites associated with phenylpropanoid metabolism, the related enzyme activities, and gene expression in cantaloupe. Treating cantaloupes with 15 mg/m3 of ozone after precooling can help maintain postharvest hardness. This treatment also enhances the production and accumulation of secondary metabolites, such as total phenols, flavonoids, and lignin. These metabolites are essential components of the phenylpropanoid metabolic pathway, activating enzymes like phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, 4CL, chalcone synthase, and chalcone isomerase. The results of the transcriptional expression patterns showed that differential gene expression related to phenylpropanoid metabolism in the peel of ozone-treated cantaloupes was primarily observed during the middle and late storage stages. In contrast, the pulp exhibited significant differential gene expression mainly during the early storage stage. Furthermore, it was observed that the level of gene expression in the peel was generally higher than that in the pulp. The correlation between the relative amount of gene changes in cantaloupe, activity of selected enzymes, and concentration of secondary metabolites could be accompanied by positive regulation of the phenylpropanoid metabolic pathway. Therefore, ozone stress induction positively enhances the biosynthesis of flavonoids in cantaloupes, leading to an increased accumulation of secondary metabolites. Additionally, it also improves the postharvest storage quality of cantaloupes.

Effects of aqueous ozone treatment on the nutritional attributes of mango (Mangifera indica L.) fruit juice

The global fruit juice market is expanding alongside the exponentially growing demand for a healthy lifestyle. Fruit juice is a preferred drink among all age groups as it contains numerous essential nutrients that benefit human health. The safety aspects of fruit juice are equally important as its healthy features. The conventional method of thermal pasteurisation has been known to produce fruit juice of inferior quality. Hence, ozone is being considered as an alternative, non-thermal form of pasteurisation. With its strong oxidation potential, ozone exhibits antimicrobial characteristics and produces no toxic by-products. However, for ozone to be successfully adopted by juice producers, the synergistic effects of the composition of fruit juice and ozone treatment must be adequately evaluated. Therefore, the present work subjected various concentrations of Chokanan mango juice (MJ), diluted with distilled water (DW) at 100MJ:0DW, 75MJ:25DW, and 50MJ:50DW to aqueous ozone treatment at different ozone doses. The effects of these treatments on the physicochemical and antioxidant properties of the MJ were evaluated. Ozone was found to be effective in decreasing the pectin methylesterase (PME) activity arising from the de-esterification of the pectin molecules, and increasing the DPPH activity, thereby increasing the juice quality. Significant effects on the total colour difference (ΔE) and total phenolic content (TPC) were observed in proportion to the increases in ozone dose. The colour of the treated MJ was found to be positively correlated with the TPC, while a kinetic study was performed to investigate the proportionality of the colour and TPC degradation. The first-order reaction model fitted well with the degradation patterns of L* and b*, as well as the ΔE of the MJ samples. A significant difference was observed between the degradation rate constant (k-value) for the MJ samples, which suggested that the k-value could have been affected by not only the ozone dose, but also the juice matrix. The present work demonstrated that the composition of fruit juice was an essential intrinsic parameter that must be assessed before adopting ozone as a form of non-thermal pasteurisation to produce fruit juice which is stable in quality, and safe for consumption.

How to comprehensively improve juice quality: a review of the impacts of sterilization technology on the overall quality of fruit and vegetable juices in 2010-2021, an updated overview and current issues

Fruit and vegetable juices (FVJ) are rich in nutrients, so they easily breed bacteria, which cause microbial pollution and rapid deterioration of their quality and safety. Sterilization is an important operation in FVJ processing. However, regardless of whether thermal sterilization or non-thermal sterilization is used, the effect and its impact on the overall quality of FVJ are strongly dependent on the processing parameters, microbial species, and FVJ matrix. Therefore, for different types of FVJ, an understanding of the impacts that different sterilization technologies have on the overall quality of the juice is important in designing and optimizing technical parameters to produce value-added products. This article provides an overview of the application of thermal and non-thermal technique in the field of FVJ processing over the past 10 years. The operating principle and effects of various technologies on the inactivation of microorganisms and enzymes, nutritional and functional characteristics, physicochemical properties, and sensory quality of a wide range of FVJ are comprehensively discussed. The application of different combinations of hurdle technology in the field of FVJ sterilization processing are also discussed in detail. Additionally, the advantages, limitations, and current application prospects of different sterilization technologies are summarized.

High-Intensity Ultrasound Processing Enhances the Bioactive Compounds, Antioxidant Capacity and Microbiological Quality of Melon (Cucumis melo) Juice

The bioactive compounds, antioxidant capacity and microbiological quality of melon juice processed by high-intensity ultrasound (HIUS) were studied. Melon juice was processed at two ultrasound intensities (27 and 52 W/cm2) for two different processing times (10 and 30 min) using two duty cycles (30 and 75%). Unprocessed juice was taken as a control. Total carotenoids and total phenolic compounds (TPC) were the bioactive compounds analyzed while the antioxidant capacity was determined by DPPH, ABTS and FRAP assays. The microbiological quality was tested by counting the aerobic and coliforms count as well as molds and yeasts. Total carotenoids increased by up to 42% while TPC decreased by 33% as a consequence of HIUS processing regarding control juice (carotenoids: 23 μg/g, TPC: 1.1 mg GAE/g), gallic acid and syringic acid being the only phenolic compounds identified. The antioxidant capacity of melon juice was enhanced by HIUS, achieving values of 45% and 20% of DPPH and ABTS inhibition, respectively, while >120 mg TE/100 g was determined by FRAP assay. Further, the microbial load of melon juice was significantly reduced by HIUS processing, coliforms and molds being the most sensitive. Thus, the HIUS could be an excellent alternative supportive the deep-processing of melon products.

Effect of Different Sterilization Methods on the Microbial and Physicochemical Changes in Prunus mume Juice during Storage

This study evaluated the pasteurization (P), ozone (O₃), ultrasonic (US), and high-hydrostatic-pressure (HHP) sterilization approaches for processing of Prunus mume regarding browning factors and microorganisms, compared with non-sterilization (control check, CK) treatment. The microorganisms (total bacterial count and fungi and yeast count) in the juice were identified after different sterilization techniques, while the quality parameter changes (degree of browning, color measurements, total phenolic content, reducing sugar, ascorbic acid, 5-hydroxymethyl furaldehyde (5-HMF), amino acid nitrogen, total soluble solids (TSS), pH value) were investigated. The results indicate that P and HHP treatment reduced non-enzymatic browning while substantially impacting the color measurements, TSS, and pH, while the sterilization effect was remarkable, with a rate exceeding 90%. Furthermore, the Prunus mume juices treated with P and HHP sterilization were used as the objects, and the CK group was used as the control group. They were placed at 4 °C, 25 °C and 37 °C, respectively, and stored in dark for 15 d. Sampling and determination were carried out on 0, 3, 6, 9, 12, and 15 d, respectively. M-&-Y (molds and yeasts) were not detected in the late storage period, and no obvious microbial growth was observed during storage, indicating that P and HHP treatments could ensure the microbial safety of Prunus mume juice. P- and HHP- treated Prunus mume juice has better quality and low temperature storage is beneficial for maintaining the quality of Prunus mume juice. Therefore, P treatment or HHP treatment combined with low temperature storage could achieve a more ideal storage effect. Overall, this study conclusively established that P and HHP methods were suitable for sterilizing Prunus mume juice. These techniques minimally affected overall product quality while better maintaining the quality parameters than the untreated juice samples and those exposed to O₃ and US treatment.

Quality Evaluation of Lemon Cordial Stored at Different Times with Microwave Heating (Pasteurization)

Consumer interest in food quality and safety has shifted over time, as consumers increasingly prefer minimally processed items. As a result, numerous non-thermal approaches have been implemented due to their potential to preserve the nutritional profile of products along with lengthening their storability. Microwaving, a green processing technique, volumetrically heats the product because of the interactions developed between charged ions, polar water molecules of foodstuff and the incoming electromagnetic waves. The study was mapped out to investigate the effect of microwave exposure time (60, 90 and 120 s) at fixed power (1000 W) and frequency (2450 MHz) on physicochemical properties, phytochemical constituents, antioxidant potential and microbial counts of lemon cordial stored at refrigerated temperature (4 ± 2 °C). The mentioned parameters were analyzed after an interval of 30–90 days. Statistical findings illustrated a highly significant (p ≤ 0.01) impact of microwave treatment and storage on titratable acidity, pH, total soluble solids, total phenolic contents, total flavonoids contents, antioxidant potential and total plate count. Sample microwaved for 120 s showed the highest pH values (2.45 ± 0.050), total soluble solids (56.68 ± 2.612 °B) and antioxidant activity (1212.03 ± 716.5 µg—equivalent of ascorbic acid per 100 mL of cordial); meanwhile, it exhibited the lowest total plate counts (1.75 ± 0.144 Log 10 CFU/mL). Therefore, microwaving can be suggested as a suitable alternate to traditional pasteurization techniques as well as to chemical preservatives.

Influence of Two Different Coating Application Methods on the Maintenance of the Nutritional Quality of Fresh-Cut Melon during Storage

This study aimed at evaluating the effects of two coating application methods, spraying and dipping, on the quality of fresh-cut melons. An alginate-based coating containing both ascorbic and citric acid was applied at two concentrations (5% and 10%) with both methods on fresh-cut melon. The nutritional quality of the products was investigated during 11 days of storage at 10 °C. The suitability and adaptability of the applied coatings on the fruit were evaluated based on rheological and microstructural properties. Moisture, carotenoids, total polyphenols and ascorbic acid content were analyzed on melon samples during storage. Results showed that the coating solution applied by the dipping method and at the highest concentration (10%), allowed to better maintain some quality characteristics of fresh-cut melon, thanks also to the better coating homogeneity and higher thickness observed through microstructural analysis.

Influence of Ozone on the Biochemical Composition of Birch Sap

Studies have shown that ozone is a good oxidizer and a strong disinfectant. There are many uses for ozone in the food industry, but there is relatively little information about the influence of ozone on biochemical composition and the capacity to reduce the number of microorganisms in birch sap. In this study, sap was ozonated at different intervals for 5 min (O3: 0.087 ± 0.009 mg L−1), 10 min, 15 min, 20 min, 25 min, or 30 min (O3: 0.99 ± 0.09 mg L−1). The parameters of the birch sap were studied immediately after the ozone treatment as well as during storage for seven days at 2 °C and for five days at 20 °C. The parameters of ozonated birch sap were compared with the parameters of fresh sap (control). The microbiological analysis included total bacterial count, lactic acid bacterial count, and yeast and mold count. Birch sap color, pH, titratable acidity, and ºBrix values were also determined. Evaluation of monosaccharides, sucrose, total sugars, and ascorbic acid was carried out in fresh sap as well as sap ozonated for 30 min, immediately after ozonation. The results show the statistical significance of the inactivation of microorganisms after treatment in most cases. The microorganism counts gradually reduced with increasing intervals of ozone treatment. The best results were obtained after 25 and 30 min of ozonation. Ozone treatment did not significantly influence the pH, titratable acidity, or °Brix statistically. Values of monosaccharides, sucrose, total sugars, and ascorbic acid were influenced within the margin of error. Ozone had a significant influence on the chroma and hue angle.

Ozone and plasma processing effect on green coconut water

In this study, the effect of plasma and ozone processing on the quality of coconut water was evaluated. For ozone processing, the samples were submitted to different ozone loads and temperatures. For atmospheric cold plasma processing (ACP), samples were exposed to plasma under different frequencies and voltages. The coconut water pH, soluble solids, titratable acidity, color, total phenolic content, and enzymatic activity were determined before and after treatments. The main compounds were also determined by NMR spectroscopy and chemometric analysis. Both processes did not change the pH values, total soluble solids, titratable acidity, and color. Chemometrics analysis of 1H NMR dataset showed no relevant changes after the processing. All ozone treatments promoted complete inactivation of POD activity and did not affect the content of phenolic compounds. After ACP, the smallest POD residual activity was observed when higher frequencies were applied, and slight changes in phenolic compounds content were observed.