Improvement of the Bioavailability of Amazonian Juices Rich in Bioactive Compounds Using Glow Plasma Technique

Non-thermal technologies for the conservation of açai pulp and derived products: A comprehensive review

Açai (Euterpe oleracea) is one of the main sustainable extractive crops in the Amazon region, widely consumed by the local population and a significant export product. This review presents the current knowledge regarding nonthermal technologies employed in açai processing. This review aims to discuss and compare the main results attained by the application of HPP, ultrasound, ozone, UV light, cold plasma, and pulsed electric field on microbial inactivation, enzymatic inhibition, and the content of anthocyanin and other bioactive compounds after açai pulp processing. The discussion compares these technologies with pasteurization, the current main technology applied to açai sanitization. This review shows that there are still many gaps to be filled concerning açai processing in thermal and non-thermal technologies. Data analysis allowed the conclusion that pasteurization and HPP are, up to now, the only technologies that enable a 5-log CFU reduction of yeasts, molds, and some bacteria in açai. However, no study has reported the inactivation of Trypanosoma cruzi, which is the major gap found in current knowledge. Other technologies, such as pulsed electric field, cold plasma, and ultrasound, require further development and process intensification studies to be as successful as HPP and pasteurization.

Efficacy of cold plasma technology on the constituents of plant-based food products: Principles, current applications, and future potentials

Cold plasma (CP) is one of the novel non-thermal food processing technologies, which has the potential to extend the shelf-life of plant-based food products without adversely affecting the nutritional value and sensory characteristics. Besides microbial inactivation, this technology has been explored for food functionality, pesticide control, and allergen removals. Cold plasma technology presents positive results in applications related to food processing at a laboratory scale. This review discusses applications of CP technology and its effect on the constituents of plant-based food products including proteins, lipids, carbohydrates, and polar and non-polar secondary plant metabolites. As proven by the publications in the food field, the influence of CP on the food constituents and sensory quality of various food materials are mainly based on CP-related factors such as processing time, voltage level, power, frequency, type of gas, gas flow rate as well as the amount of sample, type, and content of food constituents. In addition to these, changes in the secondary plant metabolites depend on the action of CP on both cell membrane breakdown and increase/decrease in the scavenging compounds. This technology offers a good alternative to conventional methods by inactivating enzymes and increasing antioxidant levels. With a waterless and chemical-free property, this sustainable and energy-efficient technology presents several advantages in food applications. However, scaling up CP by ensuring uniform plasma treatment is a major challenge. Further investigation is required to provide information regarding the toxicity of plasma-treated food products.

Effect of cold plasma processing on physicochemical and nutritional quality attributes of kiwifruit juice

Cold plasma treatment of kiwifruit juice was studied in the domain of 18-30 kV of voltage, 2-6 mm of juice depth, and 6-10 min of treatment time using the response surface methodology (RSM). The experimental design utilized was a central composite rotatable design. The effect of voltage, juice depth, and treatment time on the various responses, namely peroxidase activity, color, total phenolic content, ascorbic acid, total antioxidant activity, and total flavonoid content, was examined. While modeling, the artificial neural network (ANN) showed greater predictive capability than RSM as the coefficient of determination (R² ) value of responses was greater in the case of ANN (0.9538-0.9996) than in RSM (0.9041-0.9853). The mean square error value was also less in the case of ANN than in RSM. The ANN was coupled with a genetic algorithm (GA) for optimization. The optimum condition obtained from ANN-GA was 30 kV, 5 mm, and 6.7 min, respectively.

EFFECTS OF COLD PLASMA ON CHLOROPHYLLS, CAROTENOIDS, ANTHOCYANINS, AND BETALAINS

Plasma is considered by several researchers to be the fourth state of matter. Cold plasma has been highlighted as an alternative to thermal treatments because heat induces less degradation of thermolabile bioactive compounds, such as natural pigments. In this review, we provide a compilation of the current information about the effects of cold plasma on natural pigments, such as the changes caused by plasma to the molecules of chlorophylls, carotenoids, anthocyanins, and betalains. As a result of the literature review, it is noted that can degrade cell membrane and promote damage to pigment storage sites; thereby releasing pigments and increasing their content in the extracellular space. However, the reactive species contained in the cold plasma can cause degradation of the pigments. Cold plasma is a promising technology for extracting pigments; however, case-by-case optimization of the extraction process is required.

Evaluation of The Antioxidant Capacity of Food Products: Methods, Applications and Limitations

Assays of total antioxidant capacity (TAC) are popular in the analysis of food products. This review presents the most popular assays of TAC and their limitations, databases of TAC of food products, their application in clinical studies, and the effect of processing on the TAC of food. The importance of sample preparation for TAC assays and striking effects of digestion in the gastrointestinal tract on the TAC of food are discussed. Critical opinions on the validity of food TAC assays are considered. It is concluded that TAC methods can be useful as screening assays for food quality control and as low-cost, high-throughput tools used to discover potential antioxidant sources and follow changes in the content of antioxidants during food processing. However, effects revealed by TAC assays should be followed and explained using more specific methods.

Effect of food processing on antioxidants, their bioavailability and potential relevance to human health

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Processing alters the amount, matrix interaction, and structure of antioxidants.

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It is not easy to dissociate processing effects from food matrix effects.

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It is still difficult to make general statements on the effects of processing on bioavailability.

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Facilitated release by heat, pressure, etc. contributes to increased bioaccessibility.

It has long been recognized that the antioxidants present in fresh plant materials may be very different to those we ingest via our foods. This is often due to the use of food processing strategies involving thermal/non-thermal treatments. Current research mostly focuses on determining what is present in vegetative starting materials; how this is altered during processing; how this influences activity in the gut and following uptake into bloodstream; and which in vivo physiological effects this may have on human body. Having a better understanding of these different steps and their importance in a health-and-nutrition-context will place us in a better position to breed for improved crop varieties and to advise the food industry on how to optimize processing strategies to enhance biochemical composition of processed foods. This review provides an overview of what is currently known about the influence which food processing treatments can have on antioxidants and gives some pointers as to their potential relevance.

How does direct current atmospheric pressure glow discharge application influence on physicochemical, nutritional, microbiological, and cytotoxic properties of orange juice?

We proposed an innovative and economic method for rapid production of functionalized orange juice (OJ) with excellent nutritional properties, prolonged shelf life, and safe consumption. To reach this goal, we have employed direct current atmospheric pressure glow discharge, generated in contact with a flowing liquid cathode (FLC-dc-APGD) in a highly-throughput reaction-discharge system. It was found that controlled FLC-dc-APGD-treatment of OJ lead to increase the concentration of selected metals and phenolic compounds. The so-obtained OJ had the same qualitative composition of fragrance as the untreated one, however, its shelf life was prolonged up to 26 days. Furthermore, OJ exposed to FLC-dc-APGD-treatment did not exhibit any cytotoxic properties towards non-malignant human intestinal epithelial cell lines. On the other hand, the induction of cell cytotoxicity was observed in human colorectal adenocarcinoma cells line after FLC-dc-APGD-treated OJ application. We truly believe that produced by us functionalized OJ might be a tempting alternative to classic, non-treated by FLC-dc-APGD OJ.

Do we need cold plasma treated fruit and vegetable juices? A case study of positive and negative changes occurred in these daily beverages

Cold atmospheric pressure plasma (CAPP) is a prospective technology for various branches of industry. As such, much attention has been recently paid towards the use of CAPPs for treating fruit and vegetable beverages as they do not need any more to be thermally pasteurized or sanitized. However, this application of CAPPs is not only limited to the improvement of their shelf-life. It could also contribute to the enhancement of their nutritional properties and anticancer activity. This could be achieved due to the presence of numerous reactive oxygen and nitrogen species (RONS), produced at the plasma-liquid interface, that might contribute to the increase of the content of nutritional and bioactive compounds, simply upgrading the juices. In this context, the present review focuses on the recent advances in the CAPP-based technology towards the processing of fruit and vegetable juices. As such, a series of different CAPP-based reaction-discharge systems and their configurations are reviewed and set together with the physicochemical, nutritional, and antimicrobial characteristics of the CAPP-treated juices, providing an useful insight into the perspective development of emerging CAPP technology.

Cold Plasma Processing on Fruits and Fruit Juices: A Review on the Effects of Plasma on Nutritional Quality

This review aims to present the effects of cold plasma technology on the nutritional quality of fruits and fruit juices. This review focuses on the chemical changes induced by plasma on several bioactive compounds, such as sugars, starch, lipids, vitamins, phenolic compounds, carotenoids, and anthocyanins. The main plasma-reacting species that reacts with fruit compounds are presented and discussed. The review presents the mechanisms that lead to the improvement and degradation of the main compounds, showing both the advantages and disadvantages of cold plasma technology.

Chemical and Antimicrobial Effects of Air Non-Thermal Plasma Processing of Fresh Apple Juice with Focus on Safety Aspects

Freshly squeezed apple juice was subjected to air non-thermal plasma treatment to investigate the capability of this processing method to inactivate microorganisms and to evaluate its safety when applied to liquid food products. Two different configurations of a transient spark discharge in ambient air were tested: an electrospray system with the juice flowing directly through the high voltage needle electrode, and a batch system, where the discharge was generated onto the surface of the juice. The key physico-chemical parameters of the juice, such as pH, conductivity, color, transmittance, and Brix degree, did not significantly change upon treatment. The concentration of nitrate ions formed by the plasma was safe, while that of nitrite ions and hydrogen peroxide was initially higher than the safety limits, but decreased within 24 h post treatment. The plasma effect on individual natural components of the juice, such as sugars, organic acids, and polyphenols, treated in water solutions led to their partial or substantial decomposition. However, when these compounds were plasma-treated altogether in the juice, they remained unaffected. The antimicrobial effect of the plasma processing was evaluated via the inoculation of model microorganisms. A stronger (6 log) decontamination was detected for bacteria Escherichia coli with respect to yeast Saccharomyces cerevisiae. Plasma processing led to a substantial extension of the juice shelf-life by up to 26 days if refrigerated, which represents a promising application potential in food technology.

Cold plasma technique as a pretreatment for drying fruits: Evaluation of the excitation frequency on drying process and bioactive compounds

The present work aims to evaluate the effect of different excitation frequency (200, 500 and 800 Hz) of cold plasma technique as a pretreatment for drying tucumã. SEM images showed changes on the pretreated tucumã's surface, favoring the drying rate and diffusivity of water as well as reducing the drying time. Marginal variation of color and reduced drying time were observed in the samples treated using 200 and 800 Hz. The pretreatment improved the concentration of phenolic (45.3 mg GAE g^-1) and antioxidant compounds (799.8 µM ET) (p-value < 0.05). Carotenoids were more sensitive to the drying time, presenting significant degradation at 500 Hz. For this reason, the propose pretreatment based on the application of cold plasma technique for drying foods can preserve/improve their nutritional quality.

Atmospheric cold plasma frequency imparts changes on cashew apple juice composition and improves vitamin C bioaccessibility

This study evaluated the atmospheric cold plasma (ACP) effect on cashew apple juice composition at different frequencies (200 and 700 Hz). The impact of this non-thermal technology on the organic juice compounds after the processing and along with the in vitro digestion carried out in a simulated digestion system at 37 °C/6 h was evaluated. The changes in the juice composition were determined by NMR spectroscopy and chemometric analyses. Vitamin C and total phenolic compounds were also quantified in processed and non-processed (control) juices and after each digestion phase. The results showed decreased glucose and fructose in samples treated by ACP and an increment in malic acid concentration for ACP700. ACP increased the amount of vitamin C in the juices and did not affect the total phenolic content. The gastric digestion highlighted the pronounced effect of plasma on the juice composition, increasing all of the components detected by NMR. Cashew apple juice processed by ACP700 presented a higher concentration of malic acid and phenylalanine. An increased bioaccessibility of vitamin C was also found for ACP700. Although ACP processing has decreased some compounds' concentration, this technology improved the bioaccessibility of vitamin C - the main bioactive compound of cashew apple juice.