Effect of high pressure carbon dioxide on the quality of carrot juice

The effect of high pressure carbon dioxide (HPCD) on the quality of carrot juice was investigated. The L-value of HPCD-treated juices increased significantly (P < 0.05) as compared to untreated juices, and the a-value exhibited an increase tendency with increasing the treatment time. However, the b-value of HPCD-treated juices did not change. The browning degree (BD) and pH of HPCD-treated juices decreased, the cloud and titratable acidity (TA) increased significantly, the UV–visible spectra of juices were lower, but the total soluble solid (TSS) and the carotenoids of juices were stable. The particle size of juices treated by HPCD for 15, 30 and 45 min increased significantly (P < 0.05), for 60 min showed a noticeable decrease and was almost close to untreated juice. HPCD treatment could not alter the Newtonian flow behavior of the carrot juice, but caused a significant increase in juice viscosity (P < 0.05).Industrial relevanceCarrot juice is one of the most popular vegetable juices, but it requires severe heat treatment for protection from spoilage due to a higher pH, its heat-sensitive quality is inevitably destructed. In this study, HPCD can avoid the drawbacks of the heat treatment as a novel non-thermal pasteurization, available data are provided for the application and evaluation of HPCD in the juice industry.     

Inactivation of polyphenol oxidase in muscadine grape juice by dense phase-CO2 processing

The effect of dense phase-CO₂ processing (DP-CO₂) on polyphenol oxidase (PPO) activity, polyphenolic and antioxidant changes in muscadine grape juice under different processing pressures (27.6, 38.3, and 48.3 MPa) and CO₂ concentrations (0, 7.5, and 15%) were measured. Subsequently two DP-CO₂ conditions (48.3 MPa at 0 or 15% CO₂) were evaluated for polyphenolic and antioxidant changes during storage (4 °C, four weeks). Pressure alone was responsible for a 40% decrease in PPO activity that resulted in 16–40% polyphenolic and antioxidant losses. Increasing CO₂ from 0 to 7.5% was responsible for an additional 35% decrease in enzyme activity and a two-fold greater polyphenolic retention. However, insignificant changes in PPO activity or polyphenolic retention were observed when CO₂ was increased to 15%. During storage, juices with residual PPO activity following processing resulted in greater polyphenolic (8- to 10-fold) and antioxidant capacity (four-fold) degradation compared to control juices with no PPO activity. This study demonstrated that partial PPO inactivation can be obtained by DP-CO₂ and that CO₂ level was the primary variable influencing PPO activity and polyphenolics and antioxidant capacity retention in muscadine grape juice.     

Comparative study on cloudy apple juice qualities from apple slices treated by high pressure carbon dioxide and mild heat

Qualities of cloudy apple juices from apple slices treated by high pressure carbon dioxide (HPCD) and mild heat (MH) were evaluated. Temperatures were from 25 to 65 °C, time 20 min, and pressure 20 MPa. Polyphenol oxidase (PPO) was completely inactivated by HPCD and its minimal residual activity (RA) by MH at 65 °C was 38.6%. RA of pectin methylesterase (PME) with HPCD was significantly lower than MH and its minimum was 18%. L value of cloudy apple juice from HPCD-treated apple slices was significantly greater than that from MH-treated apple slices, however, b value, browning degree (BD) and turbidity were lower. And no differences in a value, total soluble solids, pH and conductivity were observed. After 7-day storage at 4 °C, HPCD caused no BD alteration but a significant turbidity loss. MH increased BD at 55 and 65 °C, and led to turbidity loss from 35 to 65 °C. The turbidity was not well related to RA of PME.Industrial relevanceCloudy apple juice is one of the popular fruit juices, and it requires strict processing treatment conditions to protect its quality, especially to prevent enzymatic browning and cloud loss. HPCD is one promising novel non-thermal technique and is likely to replace or partially substitute thermal processes. This study analyzed the effect of HPCD as a pretreatment means on qualities of cloudy apple juice, including inactivating enzymes which are crucial to quality control. Available data provided in this study will benefit the fruit juice industry.     

“Ice” juice from apples obtained by pressing at subzero temperatures of apples pretreated by pulsed electric fields

The impact of apple pretreatment by pulsed electric field (PEF) on juice extraction using the freezing-assisted pressing was studied. Apple discs were PEF pretreated at electric field strength of E = 800 V/cm and then air blast frozen inside the freezer (− 40 °C). Then, pressing experiments in a laboratory-pressing chamber (2–5 bars) were started at sub-zero temperature (− 5 °C). Time evolution of juice yield and its nutritional qualities were compared for PEF and untreated apple samples. High improvements of juice yield were obtained for freeze-thawed (FT) and PEF + FT samples. The combination of PEF + pressing (5 bar) at sub-zero temperature gave optimum results for juice extraction with high levels of carbohydrates, and antioxidant bioactive compounds. At fixed value of extraction yield, Y, PEF pretreatment improved nutritional parameters. E.g., at Y = 0.6, an increase in °Brix (by ≈ 1.27), carbohydrates (by ≈ 1.42), total phenolic compounds (by ≈ 1.16), flavonoids (by ≈ 1.09) and antioxidant capacity (by ≈ 1.29) was observed after PEF pretreatment.Industrial relevancePressing constitutes one of the most commonly used technologies at industrial scale to obtain fruit juices. However, during the pressing some undesirable chemical, physical and biological changes may occur in juices, thus reducing their nutritional and sensorial properties. For instance, the use of freezing-assisted pressing is a promising technique for the production of juice concentrates rich in sugars and other solids as the low temperature operation prevents undesirable modifications. But this method is rather expensive and requires strong control of the quality of “ice” juices, their sensory and compositional profiles. Thus, there is an increased search for obtaining new efficient methodologies for producing high quality juices. In this line, PEF-assisted pressing has been shown as a useful technology to increase juice yield. Therefore, the combination of PEF-assisted “ice” juice extraction by pressing of fruits at subzero temperatures may be a useful tool to improve the extraction yield of juices, thus improving their nutritional, physicochemical and sensorial properties.Keywords: “Ice” juice, Apple, Pulsed electric fields, Freezing-assisted pressing     

Flavanone glycosides in Brazilian orange juice

Authentic samples of oranges, frozen concentrated orange juice and pulp-wash, and retail samples of freshly squeezed orange juice and frozen concentrated orange juice have been collected in Brazil and analysed for the flavanone glycosides (FG) narirutin and hesperidin by reversed phase HPLC with UV detection at 280 nm. The juice from hand-squeezed fruit gave narirutin and hesperidin concentrations of 16–142 mg l⁻¹ and 104–537 mg l⁻¹, respectively. The ratio of hesperidin to narirutin showed varietal difference with Pera having the highest ratio (mean 8.4) and Baı́a the lowest (3.6). Frozen concentrated orange juice contained higher quantities of FG with narirutin ranging from 62 to 84 mg l⁻¹ and hesperidin from 531 to 690 mg l⁻¹ (after dilution to 12 °Brix). In frozen concentrated orange juice pulp-wash, the narirutin level ranged from 155 to 239 mg l⁻¹ and hesperidin from 1089 to 1200 mg l⁻¹. The analysis of 23 samples of freshly squeezed juice from the Brazilian market place showed that the FG content of most samples (9.1 to 94.8 and 105.8 to 586.6 mg l⁻¹, respectively, for narirutin and hesperidin) was similar to those found for authentic ones, indicating that these orange juices were not adulterated.     

Apple,grape or orange juice: Which one offers the best substrate for lactobacilli growth? — A screening study on bacteria viability,superoxide dismutase activity,folates production and hedonic characteristics

Fermentation can contribute to improve functional aspects of foods. The first goal of this study was to determine amongst apple, grape and orange juices, the one with the best bacterial growth performance during fermentation by Lactobacillus strains from commercial and artisanal food origins, at 40 °C for 48 h. The juice with the highest bacterial growth was evaluated for bacteria viability during 4 weeks of cold storage, superoxide dismutase (SOD) activity and folates production analyzed through HPLC/fluorimetry. Acceptability of fermented juice was appraised through hedonic analysis. Lactobacilli counts were the highest in apple and the lowest in orange juices at t = 48 h. In most cases, bacteria counts were higher in fermented (5.5 to 9.5 log CFU/ml) than in supplemented apple juices (4.2 to 5.7 log CFU/ml), at the 4th week of cold storage. SOD activity was significantly increased in all apple juices fermented by commercial Lactobacilli strains. Folates were produced in apple juices fermented by Lactobacillus plantarum and Lactobacillus rhamnosus. Apple juice was the best substrate for Lactobacillus growth and, considering bacterial viability and overall acceptance by the panelists, Lactobacillus acidophilus L10 was the most suitable strain for apple juice fermentation.     

Inactivation of Saccharomyces cerevisiae and Lactobacillus plantarum in orange juice using ultra high-pressure homogenisation

Yeasts and lactic acid bacteria are the usual contaminants in orange juice and responsible for decreasing the shelf life of the product. Ultra high-pressure homogenisation has been shown to be an alternative to the traditional thermal pasteurisation of pumpable foods. The product was pumped through a homogeniser valve at 100 MPa, 150 MPa, 200 MPa, 250 MPa and 300 MPa using two synchronized overlapped intensifiers at a flow rate of approximately 270 mL/min. The inlet temperature was kept at 10 °C, pH at 4.1 and soluble solids at 10.0 °Bx. After processing, the product was immediately cooled to 4 °C and the microbiological count was determined. The study showed that Lactobacillus plantarum and Saccharomyces cerevisiae are sensible to ultra high-pressure homogenisation treatment. The results indicated that pressures higher than 250 MPa were able to completely destroy initial loads of 1.2 × 107 UFC/mL of L. plantarum and 2.9 × 105 UFC/mL of S. cerevisiae in orange juice, making this technology a promising way to nonthermally process orange juices.Industrial relevanceThis paper deals with inactivation of microorganism contaminants of orange juice using dynamic ultra high process technology. It is of industrial interest and relevance to evaluate the use of this non-thermal emerging technology to process fluid foods that may result into better taste, optimum product functionality, safety and quality characteristics.     

Antioxidant capacity,phenolic composition and microbial stability of aronia juice subjected to high hydrostatic pressure processing

The aim of this study was to characterize the effect of high hydrostatic pressure (200–600 MPa/15 min) and storage (4 °C/80 days) on aronia juice quality. The total antioxidant capacity, phenolic content and composition were assessed using an updated analytical strategy. Microbial growth was also analyzed following juice storage. Among all the analyzed juices, the untreated aronia juice had the greatest reduction (36%) in total polyphenols over the entire storage period. At the end of the storage period, the pressurized juices demonstrated ABTS and FRAP values higher by 14% and 5% as compared to the untreated juices. The main antioxidants identified in the aronia juice were: chlorogenic acid; neochlorogenic acid; cyanidin 3-galactoside; cyanidin 3-xyloside; cyanidin 3-arabinoside; cyanidin 3-glucoside. Cyanidin 3-glucoside was the most stable compound during juice storage. Microorganism growth in juices pressurized at 400–600 MPa was below the detection limit (< 1 CFU mL^− 1) upon storage.Industrial relevanceAronia berries are rarely consumed fresh since they give off several negative sensory attributes. Multiple health-promoting properties of aronia berries make them a valuable raw material for juice production. However, processing involves pasteurization or hot-filling strongly diminishes the product quality due to the changes in quantity and quality of thermolabile phytochemicals. The objective of this work was to characterize the effect of high hydrostatic pressure on the antioxidant capacity, polyphenol content and composition and microbial stability of aronia juice. Results of this study may be useful for the juice industry commercialize this technology for the development healthy, nonclarified aronia juices with desired level of quality.     

Inactivation of food spoilage bacteria and Escherichia coli O157:H7 in phosphate buffer and orange juice using dynamic high pressure

This study aimed to evaluate the potential of dynamic high pressure (DHP) technology to inactivate pathogenic and spoilage microflora in orange juice. Escherichia coli O157:H7 ATCC 35150, Lactobacillus plantarum ATCC 14917, Leuconostoc mesenteroides ATCC 23386 and two orange juice isolates: Saccharomyces cerevisiae and Penicillium ssp. were subjected individually to different DHP treatments. The effectiveness of DHP treatment was first evaluated in phosphate buffered saline (PBS) before application in orange juice samples. The inactivation efficacy of DHP depended on the pressure applied and the number of passes. It was more efficient against Gram-negative strains than Gram-positives. Complete inactivation and 5 log reduction of E. coli O157:H7 were achieved in orange juice at 200 MPa after 5 and 3 passes at 25 °C, respectively. Lower inactivation was obtained with Penicillium ssp. (4 log), S. cerevisiae (2.5 log), L. plantarum (2.3 log) and L. mesenteroides (1.6 log). The gathered results revealed the potential of DHP to inactivate all the tested microorganisms and then, it could constitute a promising alternative technology for cold pasteurization of fruit juices.     

An exploratory study on the influence of orange juice on gut microbiota using a dynamic colonic model

The aim of this research was to evaluate the influence of fresh orange juice (FOJ) and pasteurized orange juice (POJ) on gut microbiota using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) in a long-term experiment. SHIME® vessels were used to investigate orange juice fermentation throughout the colon and to assess changes in microbial composition and fermentation metabolites (short-chain fatty acids, or — SCFA, and ammonium). Antioxidant activity of the SHIME® vessels and juice was also evaluated. The FOJ increased (p ≤ 0.05) Lactobacillus spp., Enterococcus spp., Bifidobacterium spp., and Clostridium spp. and reduced (p ≤ 0.05) enterobacteria. The POJ increased (p ≤ 0.05) Lactobacillus spp. and reduced (p ≤ 0.05) enterobacteria. The PCR-DGGE analysis showed a reduction in total bacteria population richness values. The FOJ and POJ increased (p ≤ 0.05) butyric, acetic, and propionic acid concentrations, whereas ammonium production was reduced. High values of antioxidant activity were observed as a result of the FOJ and POJ treatments. Principal component analysis indicated that both POJ and FOJ juices had a positive influence on gut microbiota. The FOJ and POJ were found to exhibit selective prebiotic activity, particularly in terms of gut microbiota. This finding is in agreement with increases in both SCFAs and commensal bacteria, as well as with decreases in ammonium levels, though total bacteria richness values were reduced.     

Effects of atmospheric cold plasma and ozone on prebiotic orange juice

In this study, the effect of plasma and ozone treatments on the quality of orange juice was evaluated. The juice was directly and indirectly exposed to a plasma field at 70 kV for different treatment times: 15, 30, 45 and 60 s. For ozone processing, different loads (0.057, 0.128 and 0.230 mg/O₃ mL of juice) were evaluated. After the treatments, the oligosaccharides were quantified by HPLC. The juice pH, color, total phenolic content and total antioxidant activity were also determined. Both processes promoted a partial degradation of the oligosaccharides in the juice. However, the juice maintained an enough amount of oligosaccharides to be classified as a prebiotic food. The phenolic content and antioxidant capacity of the treated samples was also well preserved as the pH and color. Thus, atmospheric cold plasma and ozone are suitable non-thermal alternatives for prebiotic orange juice treatment.Industrial relevanceConsumers are looking for safe food products with high quality. Thus, the food industry is currently considering non-thermal processes as an alternative to reduce the nutrient loss in processed foods. Despite atmospheric cold plasma and ozone are technologies already evaluated as an efficient non-thermal alternative for pathogens inactivation in orange juice, no previous studies on their effects on the oligosaccharides in functional fruit juice was published. This study is of industrial relevance because it demonstrates that after plasma and ozone treatment the overall quality of prebiotic orange juice was preserved and the product maintained its functional appeal.     

Degradation of various fruit juice anthocyanins by hydrogen peroxide

Degradation kinetics of anthocyanins was studied in sour cherry nectar, pomegranate and strawberry juices at high hydrogen peroxide (H₂O₂) concentrations (9.31–27.92 mmol l⁻¹) at 10–30 °C and in only sour cherry nectar at low H₂O₂ concentrations (0.23–2.33 mmol l⁻¹) at 20 °C. Degradation of anthocyanins followed the first-order reaction kinetics. Sour cherry anthocyanins were the most resistant to H₂O₂, followed by pomegranate and strawberry anthocyanins. Degradation of anthocyanins was also studied in sour cherry nectar and pomegranate juice in the presence of ascorbic acid at 60 and 80 mg l⁻¹ concentrations at 20 °C. At 80 mg level, ascorbic acid significantly accelerated the degradation of anthocyanins in sour cherry nectar at 4.65, 6.98 and 9.31 mmol l⁻¹ H₂O₂ concentrations. In contrast, ascorbic acid at both 60 and 80 mg levels protected the anthocyanins from degradation by H₂O₂ in pomegranate juice.     

Color and viscosity of watermelon juice treated by high-intensity pulsed electric fields or heat

The effects of high-intensity pulsed electric field (HIPEF) processing (35 kV/cm for 1727 μs applying 4-μs pulses at 188 Hz in bipolar mode) on color, viscosity and related enzymes in watermelon juice were evaluated during 56 days of storage and compared to thermal treatments (90 °C for 60 s or 30 s). HIPEF-treated juice maintained brighter red color than thermally treated juices along the storage time. In addition, the application of HIPEF as well as heat at 90 °C for 60 s led to juices with higher viscosity than those untreated for 56 days of storage. On the other hand, peroxidase (POD) was inactivated more efficiently after HIPEF processing than after applying heat treatments. However, the thermally processed juice at 90 °C for 60 s kept the lowest residual POD activity values beyond day 7 of storage. Differences in lipoxygenase (LOX) activity among treatments were not appreciated at day 0. However, storage time had a strong reducing influence on the enzyme activity of heat-treated samples. A substantial loss of pectin methylesterase (PME) activity (more than 50%) was observed in all the treated juices, whereas a slight reduction in polygalacturonase (PG) activity was only achieved after the HIPEF treatment. The use of HIPEF technology could be an alternative to thermal treatments and could contribute to better maintain valuable attributes of watermelon juice.Industrial RelevanceHIPEF processing is a feasible alternative to thermal treatments to obtain watermelon juice, achieving optimal inactivation of deleterious microorganisms and quality-related enzymes. HIPEF-treated watermelon juices exhibit better physical properties such as color or viscosity than thermally treated juices throughout storage. Thus, HIPEF technology can help processors to obtain juices that keep their fresh characteristics, thus being better accepted by consumers.     

Application of high power ultrasound in the supercritical carbon dioxide inactivation of Saccharomyces cerevisiae

The objective of the study was to analyze the influence of high power ultrasound (HPU) on the supercritical carbon dioxide (SC-CO₂) inactivation kinetics of Saccharomyces cerevisiae and to determine the effect of the temperature (31–41 °C), pressure (100–350 bar) and composition of the medium (YPD Broth, apple and orange juice) on the process of inactivation. Using a batch-mode SC-CO₂ at 350 bar and 36 °C, a reduction of 6.7 log-cycles was obtained after 140 min of treatment. However, when HPU (40 W ± 5 W and 30 kHz) was applied during the SC-CO₂ treatments, a reduction of 7 log-cycles was achieved after 2 min of treatment for all pressures and temperatures applied. The effect of increasing pressure (from 100 to 350 bar, 36 °C) or temperature (from 31 to 41 °C, 225 bar) did not significantly influence this inactivation level. The application of ultrasound leads to a vigorous agitation and cavitation which could accelerate the SC-CO₂ dissolving in the medium. This accelerates the penetration of CO₂ into cells and its inactivation mechanisms. In batch operations the application of HPU increases the speed of reaching saturation solubility of CO₂ in many liquid media and significantly reduces microbial inactivation times.     

Dynamics of the loss and emergence of volatile compounds during the concentration of cashew apple juice (Anacardium occidentale L.) and the impact on juice sensory quality

Concentrating cashew apple juice alters the beverage aroma and flavor, compromising consumer acceptability of the concentrated beverage. To understand the mechanisms involved in these changes, this research characterized the dynamics of the loss and emergence of volatile compounds during cashew apple juice concentration, reporting their impact on beverage sensory quality. Fresh cashew apple juice (10.3°Brix) was concentrated in a thermal-siphon type evaporator operating in a closed system. Five samples were taken throughout the concentration process with the following soluble solids contents: 11.8°Brix, 14.9°Brix, 20.2°Brix, 29.6°Brix and 42.1°Brix. Trained judges rated the aroma note intensities, described as “fresh cashew apple” and “cooked” as perceived in the fresh and concentrated beverages. The headspace volatiles of the six samples were identified and quantified by GC–MS. The results indicated the esters as the major component in the fresh juice (226.46 μg kg^− 1) representing 45.0% of the total mass of volatiles, followed by the terpenes (118.98 μg kg^− 1), acids (45.23 μg kg^− 1), aldehydes (39.10 μg kg^− 1), alcohols (18.91 μg kg^− 1), lactones (19.15 μg kg^− 1), hydrocarbons (18.02 μg kg^− 1) and ketones (11.05 μg kg^− 1). Predictive statistical models (R² > 0.956, p ≤ 0.002) revealed that on reaching 14.9°Brix, the ester concentration declined more than 90%, the terpene content almost 100%, alcohols 85%, aldehydes 80% and hydrocarbons 90%. At 14.9°Brix, the intensity of “fresh cashew apple” aroma still predominated in the juice, but the panelists detected the presence of a weak “cooked” aroma. Concentration of the beverage to 20.2°Brix or above expressively increased the cooked aroma intensity and the concentration of hydrocarbons, alcohols and some aldehydes usually associated with off-flavors such as pentanal and decanal. This raises the possibility that some of these compounds might have been formed during juice processing. Juice with better sensory quality could possibly be obtained by concentrating the beverage to levels below 20.2°Brix, recovering the esters that evaporated off the juice until ~ 15°Brix is reached, and re-adding them to the juice concentrated.     

Quality comparison of carrot juices processed by high-pressure processing and high-temperature short-time processing

The effects of high-pressure processing (HPP) at 550 MPa for 6 min and of high-temperature short-time (HTST) processing at 110 °C for 8.6 s on carrot juice were evaluated. After HPP and HTST, the total plate count (TPC) was found to significantly decrease by 4.30 and 4.88 log₁₀ CFU/mL, respectively, and yeasts and molds (Y&M) were completely inactive. HPP-treated juice showed higher carotenoids, polyphenols, antioxidant capacity, viscosity, turbidity, and lower browning degrees (BDs) than HTST-treated juice, while HTST-treated juice contained higher polyacetylenes. HPP provided a more fresh-like quality and exhibited better aroma, taste, and overall acceptability. During 20 days of storage at 4 °C, both HPP- and HTST-treated juices were microbiologically safe (i.e., TPC < 2.4 log₁₀ CFU/mL, and Y&M were not detected), and their antioxidant capacities decreased linearly due to a decrease in carotenoid and polyphenol contents. The two juices did not precipitate any solids when their particle sizes decreased, and their viscosity increased; however, their organoleptic properties deteriorated as storage time increased.Industrial RelevanceThis study was intended to develop fresher and more stable carrot juice, which is not available on the market now. Acid blanching for a proper time was proved as an effective process in preventing juice serum isolation phenomenon of HPP juice, which is more likely to be accepted by consumers. HPP-treated juice had an advantage in nutritional and organoleptic properties than HTST-treated juice. This study provided a comprehensive technical support for novel application of HPP in carrot juice processing.     

Influence of high-intensity pulsed electric field processing parameters on antioxidant compounds of broccoli juice

The effect of high-intensity pulsed electric field (HIPEF) processing parameters (electric field strength, treatment time, and polarity) on broccoli juice carotenoids, vitamin C, total phenolic (TP) content and antioxidant capacity (AC) was evaluated. Results obtained from HIPEF-processed broccoli juice were compared with those of thermally treated (90 °C/60 s) and untreated juices. HIPEF processing parameters influenced the relative content (RC) of bioactive compounds, and the relative AC (RAC). Maximum RC of lutein (121.2%), β-carotene (130.5%), TP (96.1%), vitamin C (90.1%) and RAC (5.9%) was reached between 25 and 35 kV/cm and from 2000 μs to 500 μs. The highest RAC and RC of bioactive compounds were observed in HIPEF treatments applied in bipolar mode, except for vitamin C. HIPEF-treated broccoli juice exhibited greater RC of bioactive compounds and RAC than juice treated by heat. HIPEF technology could be considered a promising option for preserving the antioxidant quality of broccoli juice.Industrial relevanceVegetable juices are becoming more and more popular because of their wide range of health-related compounds. Particularly, broccoli juice is attracting the food industry attention because it contains high amounts of vitamins, carotenoids and phenolic compounds, among other bioactive compounds. Broccoli juice requires treatment conditions that protect its microbial, nutritional and sensorial quality. HIPEF is a non-thermal technology for liquid food preservation that inactivates microorganisms and enzymes without compromising the nutritional and sensorial features of foods. Consequently, this technology could be used in the food industry as an alternative for thermal treatment to preserve the bioactive compounds present in vegetable juices, offering to consumers a healthy product.     

Physicochemical and nutritional characteristics of blueberry juice after high pressure processing

This study was carried out to investigate the impact of high pressure processing (HPP) at different pressure (200, 400 and 600 MPa) and treatment times (5, 9 and 15 min) on ascorbic acid, total phenolics, anthocyanin stability and total antioxidant capacity, were also studied at different physicochemical parameters such as pH, °Brix and color. HPP treatments resulted in more than 92% vitamin C retention at all treatment intensities. On the other hand, total phenolic content in the juice was increased, mainly after HPP at 200 MPa for all treatment times. The total and monomeric anthocyanin were similar or higher than the value estimated for the fresh juice being maximum at 400 MPa/15 min (16% increase). Antioxidant capacity values were not statistically different for treatments at 200 MPa for 5–15 min in comparison with fresh juice, however for 400 MPa/15 min and 600 MPa for all times (8–16% reduction), the lowest values were observed for total antioxidant capacity determined with TEAC method. No significant changes were observed in pH and °Brix. Color changes (a*, b*, L* and ΔE) were not visually noticeable for pressurized beverage for all pressures and times.     

Identification of odour-active compounds of pasteurised orange juice using multidimensional gas chromatography techniques

Odour-active compounds present in pasteurised orange juice were identified by gas chromatography–olfactometry (GC–O) employing heart-cut multidimensional GC techniques with olfactometry (O) and mass spectrometry (H/C MDGC–O/MS) and comprehensive two-dimensional gas chromatography–accurate mass time-of-flight MS (GC × GC–accTOFMS). Headspace solid phase microextraction sampling proved to be qualitatively adequate for the analysis of pasteurised orange juice. The GC–O approach distinguished 13 potent odour regions (detection frequency ≥ 3) in the orange juice extract, in which 7 regions were then subjected to detailed identification of the compounds that contribute to the odour, by using higher resolution H/C MDGC–O/MS. This analysis permitted the odour-active peaks to be better resolved on the ²D column, with removal from background matrix, for the seven regions. GC × GC–FID and GC × GC–accTOFMS reveal the overall complexity of the volatile compounds in the product and assisted in assignment of the isolated peaks of the odour-active compounds, confirming the identification in a number of cases. Four aldehydes (hexanal, heptanal, octanal, citral), 2 esters (ethyl butanoate, methyl hexanoate), and 4 monoterpenes (α-pinene, D-limonene, linalool, α-terpineol) were confirmed in accordance with olfactometry assessment in the processed juice. This multi-assessment instrument approach of GC–O, GC × GC, and H/C MDGC provided an effective insight into the processed orange juice aroma.