Analysis of Ascorbic Acid and Isoascorbic Acid in Orange and Guava Fruit Juices Distributed in Thailand by LC-IT-MS/MS

This work describes the determination of ascorbic acid (AA) and isoascorbic acid (IAA) in fruit juices by liquid chromatography coupled with ion trap tandem mass spectrometry (LC-IT-MS/MS), with a reversed phase column (C₁₈) and simple isocratic conditions of 0.1 % formic acid. The negative ion mode of electrospray ionization (ESI) and the MS/MS transition of m/z 175 were used for the quantitation of AA- and IAA-generated product ions with m/z 115. The method was validated in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ), precision, and accuracy. Good linearity was achieved with 0.6 and 1.8 μg/mL for the LOD and LOQ, respectively. The intraday and intermediate precisions were approximately 4 and 7 %, respectively. Recovery percentages ranged from 88 to 108 %. All validation parameters were found to be within the acceptable range for both AA and IAA. Hence, the proposed method is suitable for simultaneously determining AA and IAA. Fourteen fruit juice samples were analyzed including fruit juices from supermarkets, local markets, and laboratory preparations. Ten fruit juice samples (100 %) from different brands in the supermarkets were investigated for AA and IAA content. AA could be detected in all the samples, ranging from 5.2?±?2 to 44.4?±?1.3 μg/mL, and the values of vitamin C in 4 guava samples were less than the values specified by the manufacturer. IAA was observed in 4 of 10 samples ranging from 3.4?±?0.9 to 78.3?±?3.9 μg/mL, and the highest value of IAA was approximately two fold higher than the highest value of AA. For freshly prepared fruit juices, AA was detected in both local market- and laboratory-prepared juices. The value ranged from 13.2?±?0.9 to 105.1?±?1.3 μg/mL. In addition, the AA stability after opening the package was evaluated. The results showed that after 4 days of storage in the refrigerator, approximately 30 and 15 % losses of AA were observed for the orange and guava juices, respectively. Fresh fruit juices were thus demonstrated to be good sources of AA, with the highest value observed for guava juice prepared in the laboratory.     

Inactivation of Escherichia coli Population on Fruit Surfaces Using Ultraviolet-C Light: Influence of Fruit Surface Characteristics

Ultraviolet-C (UV-C 254 nm) light is a possible alternative for chemical disinfection of fresh fruits. However, studies on the influence of surface characteristics on the kinetics of UV-C inactivation of microorganisms on fruits are limited. In this study, UV-C inactivation of generic Escherichia coli (ATCC 23716), a nonpathogenic surrogate strain for E. coli O157:H7, was inoculated onto the skin surface intact pear, pear with surface wounds, and the skin surface of intact peach. Disc shaped (0.057 m diameter?×?0.01 m height) fruit surface were exposed at room temperature to UV-C light ranging from 0 to 7.56?±?0.52 kJ/m² and microbial inactivation kinetics was determined. Maximum reductions of 3.70?±?0.125 log CFU/g were achieved for E. coli on intact pear surfaces (P?<?0.05), with lesser reduction on wounded pear (3.10?±?0.329 log CFU/g) and peach surfaces (2.91?±?0.284 log CFU/g) after 4 min UV-C exposure at 7.56 kJ/m² UV. The Weibull scale factor (α) values of UV-C inactivation for E. coli on an intact pear surface was 0.001?±?0.0007 min (0.235?±?0.001 kJ/m²), wounded pear surface, 0.003?±?0.001 min (0.240?±?0.002 kJ/m²) and peach surface, 0.004?±?0.0004 (0.241?±?0.0008 kJ/m²). The time required for a 90 % reduction in E. coli cell numbers or the reliable life time (t _R) calculated with the Weibull model for intact pear surfaces (0.019?±?0.009 min, 0.268?±?0.017 kJ/m²) was smaller than for wounded pear (0.062?±?0.013 min, 0.348?±?0.024 kJ/m²) and peach surfaces (0.074?±?0.012, 0.371?±?0.012 kJ/m²), suggesting that the wounds on pear surfaces and trichomes (100–1000 μm) on peach surfaces helped to shield and protect microorganisms from UV-C radiation. There was likely a more uniform distribution of bacterial cells onto pear surfaces due to its smaller surface roughness, spreading coefficient, and hydrophobic nature compared to peach. Fourier transform infrared spectroscopy indicate that bacterial membrane damage (phospholipids, protein secondary structures, and polysaccharides) and changes to DNA/RNA in E. coli resulted from UV-C treatment. UV-C can reduce E. coli populations on fresh fruit surfaces, but the efficacy of UV treatment is dependent upon the morphological and surface properties of the fruit and surface integrity.     

Effects of UV-C Light Processing on Some Quality Characteristics of Grape Juices

White and red grape juices (GJs) were subjected to ultraviolet C (UV-C) light as a non-thermal preservation technology using a coiled tube UV-C reactor with nine lamps. The effects of UV-C light on microbial (total aerobic count and yeast and mould count) and some chemical quality characteristics (total phenolics, antioxidant capacity, anthocyanin and polymeric colour, etc.) of white and red GJs were investigated. The results were compared with control (untreated) and heat-treated juice samples. Single-pass UV-C treatment (12.6 J/mL) of white and red GJs resulted in 3.51 and 3.59 log reductions in total aerobic count and, 2.71 and 2.89 log reductions in yeast and mould counts, respectively. The microbial loads of both GJs were completely eliminated after two passes through the reactor (25.2 J/mL). After UV-C and heat treatments, there were no significant changes in antioxidant capacity, total phenolics, titratable acidity, soluble solids and pH of white and red GJs (P?>?0.05). The losses in monomeric anthocyanins were 6.1% and 8.7% after UV-C treatment of 12.6 and 25.2 J/mL doses, respectively. However, anthocyanin level of red GJ was significantly affected by the heat treatment with an 11.8% loss (P?<?0.05). The percent polymeric colour of the red GJ with heat treatment was significantly higher compared to the colour with the UV-C treatment.     

Phytochemical Polyphenol Extraction and Elemental Composition of Vitis labrusca L. Grape Juices Through Optimization of Pectinolytic Activity

Grape juice is a natural source of polyphenols with potential health benefits. The aim of this study was to assess the optimized basis of the pectinolytic activity through a multivariate design for the bioactive enrichment of polyphenols in grape juices and to evaluate the effect of pectinases on the extraction of minerals by ICP-MS and FAAS. Grape juices were treated with pectinases Everzym® Color and Rapidase® Smart at different conditions of enzyme concentration (0.16–1.84 g L^?1), temperature (14.8–83.6?ºC), and incubation time (9.6–110.5 min), and the effect on total phenolics, anthocyanin content, and antioxidant activity of juices were determined by employing a second-order central composite design in combination with response surface methodology. The different conditions showed significant variations in polyphenol levels of grape juices. For both of the enzymes, the increase of temperature and enzyme concentration led to a higher extraction of polyphenols, with a significant effect. Estimated effects depict a good correlation among dependent variables. For Rapidase, the optimized extraction of polyphenols was determined at an enzyme concentration of 1.57 g L^?1 and at a temperature of 54.8?ºC. For Everzym, higher concentrations of polyphenols were obtained at the enzyme concentration of 1.30 g L^?1 at 46.8?ºC. The extraction using the Rapidase enzyme significantly increased the levels of Na, K, Mg, and Fe in grape juices (p?<?0.05). The pectinolytic activity increased the polyphenol and mineral concentrations in grape juices. In addition, the optimal conditions of the pectinolytic treatment comprise a feasible alternative to improve the bioactive potential of grape juices.     

Temperature and storage effects on antioxidant activity of juice from red and white grapes

The effect of temperature and storage time on the phenolic composition and on the antioxidant activity of grape (Vitis vinifera L.) juices made using a red (Sangiovese, SG) and a white (Muscat of Alexandria, MA) variety was studied. Total phenolics, flavonoids, flavan‐3‐ols and hydroxycinnamoyl‐tartrates (HCT) were determined on grape extracts (GE) and juices. Total anthocyanins and anthocyanins composition were measured on GE. The antioxidant activity was assessed by means of two different in vitro tests: scavenging of the stable 2,2‐diphenyl‐1‐picrylhydrazyl radical and the inhibition of tyrosine nitration mediated by authentic peroxynitrite (ONOO^?). All the juices were analysed after 24 h and 2 weeks of storage by means of two‐way anova (factors being cultivar and temperature). Anthocyanins were not detected in MA extract, whereas in SG their content was 534 mg malvidin‐equivalent per 100 g of dry matter (d.m.) and malvidin derivatives (glycosylated and coumaroylated) were the most represented (respectively 169 and 41 malvidin‐equivalent per 100 g of d.m.). HCT content of the extracts was higher in SG (overall +33%). Also in grape juices, HCT were lower in MA and in this variety, the trans‐fertaric and cis‐coutaric acids were also undetectable. Cultivar effect proved to be highly significant, while no significant differences in the phenolic composition were observed for storage temperatures (4 and ?20 °C) and cultivar × temperature interaction. However, when statistical analysis was focused on each cultivar, MA was found to be more sensible to storage conditions and a significant reduction in total phenolics (?20%) and flavonoids (?53%) content and in the ONOO^? scavenging potential (?32%) was evident after 2 weeks at 4 °C (when compared with the same storage temperature after 24 h). On the contrary, SG juices did not show significant differences among the four storage treatments investigated. These results could be explained suggesting that anthocyanins presence in red grape plays a key role in juice stability.     

Relationship and correlation between antioxidant content and capacity,processing method and fruit colour of cactus pear fruit

Cactus pear fruit is a valuable source of antioxidants and could be an important functional ingredient in foods. Cultivars differ in fruit colour, which may indicate the presence of specific antioxidants. There is increased interest for cactus pear-derived products due to their potential nutraceutical effects, and determining antioxidant potential in processed foods is an important measure to ascertain the quality of a processed product. The aim of the study was to determine the relationship of fruit processing method and colour with antioxidant content and activity in fresh and processed cactus pear fruit. Antioxidant components (ascorbic acid, phenolic compounds, carotenes and betalains) and antioxidant activity (radical scavenging activity towards 2,2′-diphenyl-1-picrylhydrazyl and iron chelating capacity) were determined in fresh and processed (juiced, dried, preserved and chutney) fruits from four different coloured cultivars (purple, green, orange and pink). The highest antioxidant content and potential was found in purple (O. robusta cv Robusta) fruit products, attributed to the highest levels of betalains (1140.4 mg kg^?1). Orange fruit (O. ficus-indica) products had the second highest levels, attributed to ascorbic acid and phenolics. Betalains were highly retained in all processed products, while ascorbic acid was mostly retained in the processed products that involved minimal heat treatment. Carotene and phenolic compounds became more available for extraction during processing and showed higher levels after processing. Principal component analysis makes it possible to identify fruit colours of fresh and processed products, which were mostly associated with a specific antioxidant. In the PCA biplot, PC1 (47.93%) and PC2 (21.93%) explained 69.15% of the total variation: a processing method rather than colour-correlated products in terms of antioxidant content and potential. PCA indicated that fresh purple fruit was correlated with chelating activity and betalains, while orange fruit was clustered with phenolics, ascorbic acid, carotene and DPPH. For the processed fruit products, most were clustered together with chelating activity, DPPH and the antioxidants. Orange and pink dried products had high ascorbic acid, phenolics, carotene and DPPH values, while dried and fresh purple fruit had high betalain content and chelating activity.     

Control of Postharvest Quality in Blueberry Fruit by Combined 1-Methylcyclopropene (1-MCP) and UV-C Irradiation

The objective of this study was to investigate the effects of 1-methylcyclopropene (1-MCP) combined with UV-C irradiation on postharvest quality of blueberry fruit (Vaccinium spp. Berkeley) stored at 4 ± 1 °C for 8 days. Respiration rate, ethylene production, decay incidence, softness, color, total anthocyanin content, malondialdehyde (MDA) content, titratable acid content, soluble solid content, peroxidase (POD), phenylalanine ammonia lyase (PAL), and catalase (CAT) of treated blueberry fruit were examined. The results indicated that treatment with 1-MCP plus UV-C irradiation inhibited respiration rate, ethylene production, decay incidence, and MDA content. The combined treatment also delayed softness, color, titratable acid, and soluble solid content and improved total anthocyanin content of blueberries throughout the storage period at 4 ± 1 °C compared to the untreated samples. The efficiency of the combined treatment (1-MCP + UV-C irradiation) was better than that of 1-MCP or UV-C irradiation alone. Furthermore, combination of 1-MCP and UV-C irradiation effectively enhanced PAL and CAT activities and inhibited the increasing of POD activity in blueberries. Therefore, our results shows that 1-MCP plus UV-C irradiation treatments may be a useful method in maintaining commercial quality and extending shelf life of blueberries.     

Polyphenolic Extract of Barbary-Fig (Opuntia ficus-indica) Syrup: RP–HPLC–ESI–MS Analysis and Determination of Antioxidant, Antimicrobial and Cancer-Cells Cytotoxic Potentials

The traditionally derived syrup of Opuntia ficus-indica fruit is commonly used in homemade confectionery. Herein, the aqueous-acetone extract prepared from the Tunisian O. ficus-indica syrup was investigated. The qualitatively and quantitatively polyphenolic content was analysed using reversed-phase high-performance liquid chromatography–diode array detection (RP-HPLC–DAD) coupled to electrospray ionisation–mass spectrometry (ESI–MS). The extract contained 19.95?±?2.01 mg phenolics per gram of fresh starting material with isorhamnetin 3-O-robinobioside as the major compound (22.76%). The syrup extract showed strong antioxidant potentials as assessed by both ABTS and DPPH functional methods. It exhibited effective antimicrobial activity, particularly against Staphylococcus aureus and Staphylococcus epidermidis with a minimal bactericide concentration (MBC) of 1.3 mg phenolics/ml. Furthermore, at final concentrations in the range of 41.38–186.25 μg polyphenols/ml, the extract decreased human SH-SY5Y neuroblastoma and 3T3 fibroblast in vitro cell viability in a dose- and time-dependent manner compared to non-treated control cells. The observed effects were significantly (P?<?0.05) high against cancer lines. Extract concentrations higher than 106.43 μg/ml reduced cancer cells viability to 50–60% 1–3 h post-treatment. Further in vivo insight studies should emphasise and validate the herein obtained results.     

Juice components and antioxidant capacity of four Tunisian Citrus varieties

BACKGROUND: Juices from four Citrus species of Tunisia were investigated mainly for quality parameters and antioxidant capacity. RESULTS: Citrus reticulata (mandarin) juice had the highest content of total flavonoids (85.33 mg CE L^?1). The latter also occurred in high quantity (82.01 mg CE L^?1) in Citrus lemon (lemon) juice which was also marked by its richness in total aroma (70.16 µg mL^?1) and in total fatty acids (48.10 µg mL^?1). Mandarin and lemon juices had the highest antioxidant activity, as determined b the β‐carotene bleaching assay (26.67% and 22.67%, respectively). Citrus aurantium (bitter orange) juice was characterised by the highest content of total polyphenols (784.67 mg GAE L^?1) and by the greatest inhibition of DPPH (96.10%). Citrus sinensis (blood orange) juice was only marked by the high quantity of ascorbic acid (36.90 mg mL^?1). GC/MS analysis of juice aroma showed the predominance of limonene (48.85–69.59%) in mandarin and in bitter and blood oranges, but of camphene (89.05%) in lemon. GC analysis of juice fatty acids revealed their richness in oleic acid (23.13–39.52%). HPLC analysis of juice phenolics indicated the predominance of phenolic acids (73.13–86.40%). CONCLUSION: The Citrus species used in this study were considered valuable varieties from the point of view of antioxidant capacity and nutrition. Copyright © 2010 Society of Chemical Industry     

Pasteurization of Apple Juice Contaminated with Escherichia coli by a Combined UV–Mild Temperature Treatment

The bactericidal efficacy of ultraviolet (UV) treatments to fruit juices is limited because of their low UV transmittance; therefore, it is necessary to design combined processes to improve their lethality. This investigation was carried out to determinate the lethal effect of UV-C treatments at mild temperatures (UV-H treatments) on the UV-resistant Escherichia coli strain Spanish Type Culture Collection (STCC) 4201 suspended in apple juice. A synergistic effect was observed and the optimum temperature for the combined process was established. Subsequently, the effect of the optimized treatment on the lethality of an E. coli cocktail (STCC 4201, STCC 471, American Type Culture Collection (ATCC) 27325, ATCC 25922, and O157:H7 Chapman strain) and on freshly squeezed apple juice quality was evaluated. A UV treatment of 20.33 J/mL reached 0.61?±?0.01, 0.83?±?0.07, 1.38?±?0.04, 1.97?±?0.06, 3.72?±?0.14, 5.67?±?0.61, and more than 6 log₁₀ cycles of inactivation at 25.0, 40.0, 50.0, 52.5, 55.0, 57.5, and 60.0 °C, respectively. The optimum conditions for exploiting the synergistic effects were UV doses of 27.10 J/mL, temperature of 55.0 °C, and 3.58 min of treatment time. This treatment guaranteed more of 5 log₁₀ reductions of the cocktail of five strains of E. coli without affecting pH, °Brix, and acidity of freshly squeezed apple juice. The UV-H treatment did not increase the loss of ascorbic acid compared to the same UV treatment at room temperature but approximately doubled the inactivation of polifenoloxidase.     

Effect of Gaseous Ozone on Papaya Anthracnose

Anthracnose caused by the fungus Colletotrichum gloeosporioides is considered as one of the most devastating postharvest disease of papaya. The aim of this study was to evaluate the effectiveness of gaseous ozone as a potential antifungal preservation technique to overcome anthracnose disease of papaya during cold storage. Different concentrations of ozone (0 (control), 0.04, 1.6, and 4 ppm) were applied for various exposure durations (48, 96, and 144 h). Radial mycelia growth and conidial germination were evaluated in vitro after fungal exposure to the different levels and durations of ozone. Significant inhibition in radial mycelia growth of C. gloeosporioides was observed (p?<?0.05) in all ozone treatments as compared to the control during 8 days of incubation at room temperature (25?±?3 °C). Ozone treatment of papaya fruit with 1.6-ppm ozone for 96 h delayed and simultaneously decreased the disease incidence to 40 % whereas disease severity was rated at 1.7, following 28 days of storage at 12?±?1 °C and 80 % relative humidity. The scanning electron microscopy showed that 4-ppm ozone caused disintegration of spore structure and did not affect the cuticular surface of fruit. Thus, ozone fumigation can reduce postharvest losses of papaya caused by anthracnose.     

Study on the efficiency of ethylene scavengers on the maintenance of postharvest quality of tomato fruit

The objectives of this study were to achieve the best level of each ethylene scavenger and evaluate the effect of selected levels of treatments on some quality traits of tomato during storage. Tomato fruits were subjected to four levels of treatments: palladium-promoted nano zeolite, KMnO₄-promoted nano zeolite, 1-MCP, CaCl₂, salicylic acid (SA) and UV-C. The sampling was done at 0, 7th, 14th, 21st, 28th and 35th days of cold storage. The results showed that palladium-promoted nano zeolite 5%, KMnO₄-promoted nano zeolite 20%, 1-MCP 30 ppm, CaCl₂ 2%, SA 1% and UV-C 15 min levels had the most ethylene scavenging function. Effectiveness of the treatments in ethylene scavenging was in the order: palladium?>?KMnO₄?>?1-MCP?>?SA?=?CaCl₂?>?UV-C. The palladium-promoted nano zeolite 5% had more positive effects on phenol content, polygalacturonase activity, lycopene content, fruit firmness and weight loss, and UV-C 15 min had effect on decay severity as compared to the other treatments. Overall, palladium-promoted nano zeolite 5% could be considered not only as favorable tool in tomato shelf life extension but also in preservation of quality characteristics of tomato fruits during storage. Moreover, the UV-C 15 min treatment could be an effective method for reducing decay severity and maintaining postharvest quality of tomato fruits.     

Biological activity and chemical composition of different berry juices

Total phenolics, total anthocyanins, mineral content, radical scavenging activity and antiproliferative activity against human cancer cell lines were evaluated in fresh pressed juices of five different berries. Total phenolic content ranged from 133.0 to 260.3 mg of gallic acid equivalents/100 g of fresh weight, for red currant and black currant, respectively. Bilberry juice contained the highest amount of total anthocyanins (0.18%). Significant correlation between total phenolics content and radical scavenging activity was observed (r = −0.980; p < 0.01). All examined juices showed antiproliferative activity in dose-dependent manner with IC₅₀ ranging from 10.2 to 70.5 μl/ml. Black currant juice was the most effective inhibitor of proliferation in all cell lines tested (HeLa, Fem X, LS 174, MCF-7 and PC-3). Significant correlations of acidity and total anthocyanin content with antiproliferative activity of berry juices on HeLa cells, Fem X cells and MCF-7 cells were noticed. Berry juices are good sources of some minerals and contribute significantly to daily intake of these micronutrients.     

An investigation of antioxidant capacity of fruits in Singapore markets

The antioxidant capacity of a group of fruits obtained in the Singapore markets was investigated. A total of 27 fruit pulps were tested for their general antioxidant capacity based on their ability to scavenge 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) free radical. The contribution of l-ascorbic acid (AA) to the total antioxidant activity of fruits was investigated by using RP-HPLC. The antioxidant capacity of the fruit pulp was measured by monitoring the change of absorbance of the free radical solution at 414 nm in the test reaction mixture following addition of the fruit extract, as compared with AA. The results were expressed as mg of AA equivalents per 100 g, i.e. the quantity of AA required to produce the same scavenging activity as the extract in 100 g of sample (l-ascorbic acid equivalent antioxidant capacity, AEAC). Total antioxidant capacities of AA acid, trolox, hydroquinone, pyrogallol and several fruits were also evaluated based on its ability to scavenge the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical. Results obtained were compared with those of ABTS assay. Every mol of AA, trolox or hydroquinone, was found to reduce about 2 mol of ABTS⁺ or DPPH. However, 4 mol of DPPH or 7 mol of ABTS⁺ were scavenged by every mol of pyrogallol. A good correlation of AEAC was observed between the two methods. Both methods have been recommended to be useful tools to evaluate antioxidant capacities of fruits. According to the AEAC value of binary extract solution of fruits in the ABTS model, ciku shows the highest antioxidant capacity, followed by strawberry, plum, star fruit, guava, seedless grape, salak, mangosteen, avocado, orange, solo papaya, mango, kiwi fruit, cempedak, pomelo, lemon, pineapple, apple, foot long papaya, rambutan, rambutan king, banana, coconut pulp, tomato, rockmelon, honeydew, watermelon and coconut water. The AA contribution to AEAC of fruits varied greatly among species, from 0.06% in ciku to 70.2% in rambutan.     

Characterization of Anthocyanins in Fruit of Kadsura coccinea (Lem.) A.C. Smith by UPLC/Q-TOF-MS Analysis and Evaluation of Stability of the Major Anthocyanins

Anthocyanins in fruit of Kadsura coccinea (Lem.) A.C. Smith were identified by ultra-performance liquid chromatography–quadrupole–time of flight mass spectrometry analysis. Contents of anthocyanins in K. coccinea fruit were determined by HPLC analysis. Colour stability, thermal degradation and antioxidant activity of purified cyanidin-3-xylosylrutinoside were further analysed. As a result, four anthocyanins were identified as delphinidin-3-xylosylrutinoside (1), cyanidin-3-glucosylrutinoside (2), cyanidin-3-xylosylrutinoside (3), and cyanidin-3-rutinoside (4). The individual content of anthocyanins identified was 4.36?±?0.06, 3.01?±?0.03, 49.92?±?0.76 and 2.33?±?0.04 mg/500 g deseeded K. coccinea fruit, respectively. Cyanidin-3-xylosylrutinoside was stable at pH around 1. Moreover, cyanidin-3-xylosylrutinoside was very sensitive to temperature change and it was even unstable at room temperature. Cyanidin-3-xylosylrutinoside tended to degrade into cyanidin-3-rutinoside, cyanidin-sambubioside and cyanidin at high temperatures. Cyanidin-3-xylosylrutinoside exhibited much better 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical scavenging activities than those of butylated hydroxytoluene. However, cyanidin-3-xylosylrutinoside and other three anthocyanin components contributed little to the antioxidant activity of K. coccinea fruit.     

Effect of Cold Atmospheric Plasma on Inactivation of <Emphasis Type="Italic">Escherichia coli</Emphasis> and Physicochemical Properties of Apple,Orange, Tomato Juices,and Sour Cherry Nectar

In this study, orange, tomato, apple juices, and sour cherry nectar were exposed to an atmospheric pressure plasma jet. Plasma treatments were carried out using air as a precursor under constant gas flow (3000 L/h) at 650 W for different treatment times (30, 60, 90, and 120 s). After plasma processing, reduction of Escherichia coli, Hunter’s color parameters (L*, a*, b*), total phenolic content, and pH values were evaluated. The inactivation effect of cold atmospheric plasma (CAP) was investigated on E. coli, and the highest significant reductions were achieved in apple juice (4.02 ± 0.03 log CFU/mL) followed by sour cherry (3.34 ± 0.09 log CFU/mL), while the values in orange (1.59 ± 0.17 log CFU/mL) and tomato juices (1.43 ± 0.22 log CFU/mL) were lower, which could be attributed to the food matrix. Color parameters, except for apple juice, did not show significant changes after processing. Compared to untreated juice, plasma treatment yielded higher phenolic content from 10 to 15%, while pH values did not change significantly and the temperature remained below 40 °C after all plasma treatments. This study showed that CAP treatment had positive influences on phenolic stability and color change in all samples regardless of food intrinsic factors, while it was more effective on bacterial inactivation in clear juices than turbid ones. Our results indicate that atmospheric plasma appears to be a promising technology for microbial inactivation without causing undesirable changes in food product.     

Evaluation of health-related composition and bioactivity of five fruit juices following Lactobacillus plantarum fermentation and simulated digestion

This study identified and compared the health-related components and bioactivity of five fruit juices following Lactobacillus plantarum NRRL-B-14768 fermentation and subsequent simulated gastrointestinal digestion. After 48-h fermentation, the vitamin C and total phenol content of orange juice, the polysaccharide content of watermelon juice and the content of functional elements in orange and tomato juices were relatively high. FTIR spectroscopy was used to reveal changes in phenols and organic acids. During fermentation, orange juice displayed the best 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) free radical scavenging capacities and inhibition of α-glucosidase (α-GC) and xanthine oxidase (XO), compared to the other fruit juices. After simulated gastrointestinal digestion, fermented orange juice had the highest vitamin C content, DPPH and ABTS free radical scavenging capacities and XO inhibitory activity, and fermented pineapple juice had the highest α-GC inhibitory activity. These results indicated the potential of these juices in producing fermented juice with high specific functionality.     

Preservation of hermaphrodite and female papaya fruits (Carica papaya L ., Cv Sunrise, Solo group) by freezing: physical, physico-chemical and sensorial aspects

The physical, physico-chemical and sensorial changes that occur during the freezing and frozen storage of hermaphrodite and female papaya slices (Carica papaya L., cv Sunrise, Solo group) were studied. Samples were evaluated by panellists throughout a 1-year period of storage at –24°C; the panellists described the fruit in terms of physico-chemical measurements of texture (firnmess and total pectins content), colour [L, a _L , b _L , peroxidase (POD) and polyphenoloxidase (PPO) activities] and flavour/taste [soluble solids content, pH, tritatable acidity and quality index (^oBrix/acidity)], and ranked them in order of preference. Desserts prepared from frozen slices of hermaphrodite and female papaya fruits mixed with orange, lemon and sugar were also evaluated. The freezing process itself did not result in significant changes in the more commonly assessed quality parameters of texture, colour and flavour/taste. However, during storage at –24°C, changes in sensorial characteristics occurred that became more evident as storage continued (≤ 9 months). Nevertheless, these quality changes can be masked by using these papaya slices as an ingredient in fruit products, with frozen female papaya slices being especially suitable for this purpose.     

Total Phenolics, Flavonoids, and Antioxidant Activity of Sage (Salvia officinalis L.) Plants as Affected by Different Drying Methods

In the current study, we determined the effects of seven drying methods on total phenolics, flavonoids, individual phenolics, and antioxidant activity of the methanol extract of Salvia officinalis L. As compared with total phenolic content (TPC) of fresh plants, results showed that the highest TPC was recorded in plants dried by microwave (MW) at a power of 800 W/30 g of fresh plant and was 4.2 times higher than that of fresh plants whereas the lowest content was found in the case of plants dried by far-infrared (FIR) at 45 °C. The analysis of the different extracts by RP-HPLC showed a predominance of phenolic acids particularly in fresh plants and those dried by MW (600 W/30 g of fresh plant) whereas flavonoids predominate in the case of plants dried by FIR (65 °C). The assessment of the radical scavenging activity (RSA) against the stable radical 1,1-diphenyl-1-picrylhydrazyl (DPPH) showed an increase in the scavenging effect particularly in MW (800 W/30 g of fresh plant) dried plants with an IC50?=?13.49 μg ml^?1 (IC50 is the concentration required to cause 50 % DPPH inhibition). The complementary assessment of the RSA using the β-carotene/linoleic acid system showed an increase of this activity for all extracts and particularly for the extract derived from MW (600 W/30 g of fresh plant) dried plants as compared to fresh ones. Finally, all the plant extracts showed moderate reducing power as assessed by the ferric-reducing antioxidant potential. These results suggested that MW drying could be applied to retain phenolic contents and to enhance antioxidant activity of sage plant materials.     

Grape Marc Powder: Physicochemical and Microbiological Stability During Storage and Moisture Sorption Isotherm

In the present work, the stability of grape marc powder was evaluated during its storage at room conditions for 6 months. Grape juice marc from Vitis labrusca cv. “Isabel” was dried to 8.8?±?0.9 % moisture content (wet basis) in forced convection drying equipment at 70 °C, crushed and stored aseptically in dark polyethylene bags and kept at 25?±?2 °C for up to 6 months. Grape marc powder was microbiologically safe, free of Salmonella sp., Bacillus cereus, and fecal coliforms. Total phenolic compounds with 1,1-diphenyl-2-pic-ryl-hydrazyl (DPPH) scavenging capacity and ferric reducing antioxidant power (FRAP) were stable, although monomeric anthocyanins and compounds with the capability of scavenging 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radicals showed to be susceptible to degradation through the storage period. Moisture sorption isotherm at 25 °C for the powder material was determined by static gravimetric methodology. The sorption isotherm of the grape marc powder showed a sigmoidal shape (type II), typical of food materials. The experimental data was satisfactorily fitted by the GAB (Guggenheim–Anderson–de Boer) model, giving a monolayer moisture content (X _m) of 6.75 % (dry basis). Results indicate that grape marc powder can be considered as a potential functional ingredient with an acceptable stability.