Effect of UV Irradiation on the Nutritional Quality and Cytotoxicity of Apple Juice

Application of electrospun chitosan-based nanofibers as immobilization matrix for biomolecules

Nanofiber meshes from electrospun chitosan, highly modified with biotin and arylazides, are well-suited for application as enzyme immobilization matrices. To test this, catalytically active biomolecules were immobilized onto photocrosslinked nanofibrous nonwovens consisting mainly of biotinylated fungal chitosan and a small amount (10 w%) of poly ethylene oxide. In this study, we show that over 10 μg eugenol oxidase per milligram dry polymer matrix can be loaded on UV-crosslinked chitosan nanofibers. We further demonstrate that bound enzyme activity can be fully retained for over 7 days of storage at ambient conditions in aqueous buffer. Samples loaded at maximum enzyme carrying capacity were tested in a custom-made plug-flow reactor system with online UV-VIS spectroscopy for activity determination. High wettability and durability of the hydrophilic chitosan support matrix enabled continuous oxidation of model substrate vanillyl alcohol into vanillin with constant turnover at flow rates of up to 0.24 L/h for over 6 h. This proves the above hypothesis and enables further application of the fibers as stacked microfluidic membranes, biosensors, or structural starting points for affinity crosslinked enzyme gels. KEY POINTS: • Biotinylated chitosan-based nanofibers retain enzymes via mild affinity interactions • Immobilized eugenol oxidase shows high activity and resists continuous washing • Nanofiber matrix material tolerated high flow rates in a continuous-flow setup.

Does an apple a day keep away diseases? Evidence and mechanism of action

Apples and their products exemplify the recently reemphasized link between dietary fruit intake and the alleviation of human disease. Their consumption does indeed improve human health due to their high phytochemical content. To identify potentially relevant articles from clinical trials, some epidemiological studies and meta-analyses, and in vitro and in vivo studies (cell cultures and animal models), PubMed was searched from January 1, 2012, to May 15, 2022. This review summarized the potential effects of apple and apple products (juices, puree, pomace, dried apples, extracts rich in apple bioactives and single apple bioactives) on health. Apples and apple products have protective effects against cardiovascular diseases, cancer, as well as mild cognitive impairment and promote hair growth, healing of burn wounds, improve the oral environment, prevent niacin-induced skin flushing, promote the relief of UV-induced skin pigmentation, and improve the symptoms of atopic dermatitis as well as cedar hay fever among others. These effects are associated with various mechanisms, such as vascular endothelial protection, blood lipids lowering, anti-inflammatory, antioxidant, antiapoptotic, anti-invasion, and antimetastatic effects. Meanwhile, it has provided an important reference for the application and development of medicine, nutrition, and other fields.

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.

Investigating the Use of Ultraviolet Light Emitting Diodes (UV-LEDs) for the Inactivation of Bacteria in Powdered Food Ingredients

The addition of contaminated powdered spices and seasonings to finished products which do not undergo further processing represents a significant concern for food manufacturers. To reduce the incidence of bacterial contamination, seasoning ingredients should be subjected to a decontamination process. Ultraviolet light emitting diodes (UV-LEDs) have been suggested as an alternative to UV lamps for reducing the microbial load of foods, due to their increasing efficiency, robustness and decreasing cost. In this study, we investigated the efficacy of UV-LED devices for the inactivation of four bacteria (Listeria monocytogenes, Escherichia coli, Bacillus subtilis and Salmonella Typhimurium) on a plastic surface and in four powdered seasoning ingredients (onion powder, garlic powder, cheese and onion powder and chilli powder). Surface inactivation experiments with UV mercury lamps, UVC-LEDs and UVA-LEDs emitting at wavelengths of 254 nm, 270 nm and 365 nm, respectively, revealed that treatment with UVC-LEDs were comparable to, or better than those observed using the mercury lamp. Bacterial reductions in the seasoning powders with UVC-LEDs were less than in the surface inactivation experiments, but significant reductions of 0.75-3 log10 colony forming units (CFU) were obtained following longer (40 s) UVC-LED exposure times. Inactivation kinetics were generally nonlinear, and a comparison of the predictive models highlighted that microbial inactivation was dependent on the combination of powder and microorganism. This study is the first to report on the efficacy of UV-LEDs for the inactivation of several different bacterial species in a variety of powdered ingredients, highlighting the potential of the technology as an alternative to the traditional UV lamps used in the food industry.

Efficacy of light-emitting diodes emitting 395, 405, 415, and 425 nm blue light for bacterial inactivation and the microbicidal mechanism

We investigated the bactericidal effects against Escherichia coli O157:H7 of light-emitting diodes (LEDs) emitting blue light of four different peak wavelengths ranging from 395 to 425 nm in water. Furthermore, we investigated inactivation in the presence of reactive oxygen species (ROS) scavengers to elucidate the contribution of bacterial inactivation. An aluminum chamber was constructed and coated in carbon to block exterior light, and a single blue light LED with a rear heat sink was attached to the chamber lid. Effective inactivation of the pathogen was observed for all blue light LED irradiation at 305, 405, 415, and 425 nm. The log-linear with shoulder and tail model and log-linear model described the survival of the bacteria after blue light LED treatments. Not just the effects of ROS but also photophysical effects were shown with the addition of mannitol, a ROS scavenger. The integrity of the cell membrane was damaged regardless of the presence of ROS, which indicates that photophysical effects were sufficient to induce damage to the cell membrane. In addition, activity of succinate-coenzyme Q reductase, which participates in respiratory metabolism to generate energy, decreased in the absence of ROS and decreased further in the presence of ROS.

Comprehensive studies on the properties of apple juice treated by non-thermal atmospheric plasma in a flow-through system

We present an optimized non-thermal atmospheric plasma (NTAP)-based reaction-discharge system that was applied for a continuous-flow treatment of apple juice (AJ). To optimize this system for a high-throughput production of AJ with ameliorated properties, the effect of several parameters was studied using design of experiments approach followed by the response surface methodology. Additionally, nutritional, physicochemical, microbiological and cytotoxic properties of resulting AJ were assessed. It was established that NTAP treatment of AJ led to rise in concentration of Ca, Fe, K, Mg, Na and Sr by 8–10% as well as Al, B, Ba, Cu, Mn and Zn by 11–15%. Additionally, the increased total phenolic content by ~ 11% in addition to the prolonged by up to 12 days shelf life of the product were observed. Moreover, it was found that the NTAP-treatment of AJ did not change the structure of organic compounds present in AJ, in addition to its °Brix value, color and ferric ion reducing antioxidant power. Furthermore, AJ subjected to NTAP did not show any cytotoxic activity towards non-malignant human intestinal epithelial cells but exhibited induced cell cytotoxicity in human colorectal adenocarcinoma cells. Our study provided arguments for future introduction of these types of preparations to the global market.

Effect of UV-C irradiation on the inactivation kinetics of oxidative enzymes, essential amino acids and sensory properties of coconut water

The impact of ultraviolet light (UV-C) irradiation on oxidative enzymes [Polyphenol oxidase (PPO) and Peroxidase (POD)], free essential amino acids and sensory profile of coconut water were investigated. PPO and POD activities were lost to 94 and 93%, respectively of its original value at fluence level of 400 mJ/cm2. Inactivation kinetics of both enzymes were fitted to nonlinear Weibull model with an increase in UV dosage with a high coefficient of determination (R2 > 0.97) and low root mean square error (RMSE < 0.06). No significant change was observed in all essential amino acids (p > 0.05) after UV-C treatment up to maximum delivered fluence of 400 mJ/cm2. Sensory attributes of coconut water up to a treated UV-C fluence level of 200 mJ/cm2 were well retained in terms of chosen descriptors (p > 0.05). This study allow to further investigate the development of UV-C light technology for inhibition of spoilage enzymes and prolonged shelf-life of low acid beverages.

Application of cold atmospheric pressure plasmas for high-throughput production of safe-to-consume beetroot juice with improved nutritional quality

A one-step, highly-efficiency, and low-cost cold atmospheric pressure plasma (CAPP)-based method for obtaining safe-to-consume beetroot juice (BRJ) with enhanced nutritional quality is presented. Three reaction-discharge systems with different CAPPs were studied to check how the composition and physicochemical properties changed during CAPP treatment of BRJ. To identify reactive species occur in gas phase of applied CAPP for BRJ treatment, optical emission spectrometry was used. Finally, the cytotoxicity of so-obtained BRJ to human epithelial colorectal adenocarcinoma (Caco-2) and human non-malignant intestine microvascular endothelial cells (HIMEC) was assessed. Based on the performed analyses it was found that controlled CAPP treatment of BRJ changes the fraction pattern of elements in addition to increase the content of phenolic compound presents in BRJ. Furthermore, the defined CAPP treatment of BRJ inhibits proliferation of Caco-2 cell lines, exhibiting non-cytotoxic effect for HIMEC non-malignant endothelial cells. As a result, safe-to-consume BRJ of improved nutritional quality was produced.

Zein Particle-Stabilized Water-In-Water Emulsion as a Vehicle for Hydrophilic Bioactive Compound Loading of Riboflavin

Vitamins and flavonoids are two kinds of essential trace bioactives which are prone to photodegradation during food processing and storage. In this study, a particle-stabilized water-in-water (W/W) emulsion system composed of soy protein isolate (SPI) and guar gum (GG) was applied in loading riboflavin. Based on the significant binding affinity differences of SPI (K_a = 1.11 × 10⁵ L mol^-1) and GG (K_a = 9.00 × 10³ L mol^-1) to riboflavin, this hydrophilic and light-sensitive bioactive compound was loaded in SPI-rich droplets. Confocal images indicated that a stable microstructure of SPI-rich droplets suspended in GG-rich continuous phase was successfully constructed by manipulating the proportion of the two polymeric components and using zein-based particles (ZPs) as stabilizers. These negatively charged particles modified by pectin with a hydrodynamic diameter of 533 ± 5.7 nm were able to adsorb at the SPI/GG interface and subsequently stabilized the SPI-in-GG emulsion. Fluorescence spectra of riboflavin suggested that the formation of such W/W emulsion could effectively delay the photodegradation of riboflavin during an 8 h ultraviolet irradiation, and its color was maintained to a maximum extent. Therefore, this structured W/W emulsion could be a desired architecture for delivering light-sensitive cargo.

Ultraviolet inactivation of bacteria and model viruses in coconut water using a collimated beam system

This study investigated the effect of ultraviolet-C irradiation on the inactivation of microorganisms in coconut water, a highly opaque liquid food (1.01 ± 0.018 absorption coefficient). Ultraviolet-C inactivation kinetics of two bacteriophages (MS2, T1UV) and three surrogate bacteria (Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes) in 0.1% (w/v) peptone and coconut water were investigated. Ultraviolet-C irradiation at 254 nm was applied to stirred samples, using a collimated beam device. A series of known ultraviolet-C doses (0-40 mJ cm^-2) were applied for ultraviolet-C treatment except for MS2 where higher doses were delivered (100 mJ cm^-2). Inactivation levels of all organisms were proportional to ultraviolet-C dose. At the highest dose of 40 mJ cm^-2, three surrogates of pathogenic bacteria were inactivated by more than 5-log₁₀ (p < 0.05) in 0.1% (w/v) peptone and coconut water. Results showed that ultraviolet-C irradiation effectively inactivated bacteriophage and surrogate bacteria in highly opaque coconut water. The log reduction kinetics of microorganisms followed log-linear and exponential models with higher R² (>0.95) and low root mean square error values. The D₁₀ values of 3, 5.48, and 4.58 mJ cm^-2 were obtained from the inactivation of E. coli, S. Typhimurium, and L. monocytogenes, respectively. Models for predicting log reduction as a function of ultraviolet-C irradiation dose were found to be significant (p < 0.05). Fluid optics were the key controlling parameters for efficient microbial inactivation. Therefore, the ultraviolet-C dose must be calculated not only from the incident ultraviolet-C intensity but must also consider the attenuation in the samples. The results from this study imply that adequate log reduction of vegetative cells and model viruses is achievable in coconut water and suggested significant potential for ultraviolet-C treatment of other liquid foods.

Isolation, Identification, and Quantification of Tyrosinase and α-Glucosidase Inhibitors from UVC-Irradiated Mulberry (Morus alba L.) Leaves

Methanol extracts from ultraviolet (UV) C-irradiated mulberry leaves (UVC-IML) exhibit stronger tyrosinase and α-glucosidase inhibitory activities than those from unirradiated mulberry leaves. Through a bioassay-guided fractionation and purification process, two oxyresveratrol derivatives, oxyresveratrol (ORT) and 4′-prenyloxyresveratrol (PORT), and six 2-arylbenzofuran derivatives [moracin B (MCB), moracin C (MCC), moracin M (MCM), moracin N (MCN), 6,5′-dimethoxymoracin M (DMMCM), and chalcomoracin (CMC)] were isolated from the methanol extract from UVC-IML. Their chemical structures were determined by UV, mass, and nuclear magnetic resonance spectrometry. ORT and PORT showed potent tyrosinase inhibitory activities with the half maximal inhibitory concentration (IC₅₀) values of 0.57 and 0.90 μM, respectively, and CMC exhibited significant tyrosinase and α-glucosidase inhibitory activity with IC₅₀ values of 5.61 and 6.00 μM, respectively. Levels of these eight compounds were increased significantly following irradiation compared with untreated mulberry leaves; ORTs increased approximately 4 fold and moracins increased 2~16 fold. These data suggest that UVC-IML may represent a promising source of nutraceuticals and cosmeceuticals for prevention of diabetes and skin aging.

UV-C Irradiation on the Quality of Green Tea: Effect on Catechins, Antioxidant Activity, and Cytotoxicity

Short-wavelength ultraviolet (UV-C) irradiation is a nonthermal processing technique that is a possible alternative to the heat-pasteurization of tea beverages. This study investigated the effect of UV-C irradiation on the polyphenolic and total phenolic contents of a green tea beverage and analyzed cytotoxicity of irradiated green tea using a novel continuous flow-through UV system. UV-C fluence levels ranging from 0 to 240 mJ/cm² were delivered to green tea, and polyphenols were chemically profiled. Continuous-flow UV-C irradiation of the green tea beverage at a fluence of 68 mJ/cm²  induced a minor reduction in the concentration of the most abundant catechin in green tea, (-)-epigallocatechin gallate (EGCG), from 145 to 131.1 μg/mL. The total phenolic content of the green tea beverage was 0.19 μg GAE/uL and remained constant at all UV fluence levels. The UV-treated green tea beverage showed no cytotoxic effects on normal intestinal cells with healthy colonic cells (CCD-18Co) maintained at 90% viability for the UV-treated green tea beverages and the control. The treated and nontreated green tea have comparable inhibitory effects on the survival of human colon cancer cells. Overall, these results demonstrate that the UV-C irradiation did not significantly deplete catechins or produce cytotoxic byproducts.

PRACTICAL APPLICATION

Short wavelength ultraviolet (UV-C) irradiation is a nonthermal processing technique that is a possible alternative to the heat pasteurization of tea beverages. This study investigated the effect of UV-C irradiation on the antioxidant concentration of green tea and analyzed cytotoxicity of irradiated a green tea beverage using a novel continuous flow-through UV system. The results demonstrated that the UV-C irradiation did not significantly deplete catechins or produce cytotoxic byproducts.