Spray‐drying of pomegranate juice with prebiotic dietary fibre

The prebiotic fibres, resistant dextrin and fructooligosaccharides (FOS), were studied for use as drying‐aid agents for the spray‐drying of concentrated pomegranate juice, a low‐caloric juice containing interesting health‐related compounds. Resistant dextrin was the best drying‐aid agent as only 0.5 g g_CPJ^?1 of resistant dextrin was needed to avoid powder stickiness, compared with 1 g g_CPJ^?1 of maltodextrins and 1.5 g g_CPJ^?1 of fructooligosaccharides. The best conditions for spray‐drying a concentrated pomegranate juice (62.6% dry matter) using the resistant dextrin (NUTRIOSE) were 1.25 g_NUTRIOSE g_CPJ^?1 and 0.10 g_CPJ g_solution^?1, a liquid feed rate of 1.08 L h^?1 and an air temperature of 160 °C. Powders were easily solubilised in water, while storage at 25 °C maintained the pomegranate bioactive components, and there were no stickiness problems for at least 2 months. Resistant dextrin could be used with all kind of fruit juices in substitution of maltodextrins, and the resulting prebiotic powders could be employed for formulating novel functional foods.     

Microbial Safety and Shelf Life of UV‐C Treated Freshly Squeezed White Grape Juice

The effects of UV‐C irradiation on the inactivation of Escherichia coli K‐12 (ATCC 25253), a surrogate of E. coli O157:H7, and on the shelf life of freshly squeezed turbid white grape juice (FSWGJ) were investigated. FSWGJ samples were processed at 0.90 mL/s for 32 min by circulating 8 times in an annular flow UV system. The UV exposure time was 244 s per cycle. The population of E. coli K‐12 was reduced by 5.34 log cycles after exposure to a total UV dosage of 9.92 J/cm² (1.24 J/cm² per cycle) at 0.90 mL/s flow rate. The microbial shelf life of UV‐C treated FSWGJ was extended up to 14 d at 4 °C. UV exposure was not found to alter pH, total soluble solid, and titratable acidity of juice. There was a significant effect (P < 0.05) on turbidity, absorbance coefficient, color, and ascorbic acid content. Furthermore, all physicochemical properties were altered during refrigerated storage. The microbial shelf life of FSWGJ was doubled after UV‐C treatment, whereas the quality of juice was adversely affected similarly observed in the control samples.     

Descriptive analysis of bacterial profile,physicochemical and sensory characteristics of grape juice containing Saccharomyces cerevisiae cell wall‐coated probiotic microcapsules during storage

In this study the feasibility of incorporation of probiotic microcapsules coated with fragmented yeast cell wall in grape juice was evaluated during 60 days at 4 °C. Lactobacillus acidophilus and Bifidobacterium bifidum were encapsulated in alginate microbeads and coated with fragmented Saccharomyces cerevisiae cell wall and calcium alginate and were added into grape juice. At the end of storage, the survival of probiotics was higher than recommended minimum value (10⁷ cfu mL^?1) and the results demonstrated that applying yeast cell wall layer for L. acidophilus microcapsules significantly enhanced its survival while did not affect the survival of B. bifidum (P > 0.05). Generally, probiotic grape juice showed decrease in °Brix, pH and colour and increase in acidity and turbidity during storage and the presence of yeast wall layer had no significant effect on its properties expect colour and turbidity. Overall acceptance of grape juices containing yeast cell wall‐coated microcapsules scored the least.     

Stability of oil–water primary emulsions stabilised with varying levels of casein and whey proteins affected by high-intensity ultrasound

This study evaluates physical and chemical stability of ultrasound-assisted grape seed oil primary emulsions stabilised by varying compositions of caseins to whey proteins (80:20, 60:40, 50:50 and 40:60) at different sono-operating conditions (81.9 and 117.0 J mL⁻¹). Physical and chemical stabilities were influenced by both sonication energy densities and milk protein compositions. Emulsions prepared at 81.9 J mL⁻¹ energy density with ≥40% whey protein fraction (60:40, 50:50, 40:60 and WPI) showed greater physical stability than the emulsions sonicated at 117.0 J mL⁻¹ which exhibited physical instability due to the depletion flocculation mechanism at the critical casein concentration (≥40%). The emulsion oxidative stability was found to be affected by sonication conditions as 117.0 J mL⁻¹ induced the oxidation reactions once the whey concentration exceeds 40%. Therefore, ultrasound prepared emulsions with casein to whey ratios of 60:40, 50:50, 40:60 and WPI at 81.9 J mL⁻¹ energy density was found to be stable for 10 days at 4 °C.     

Zinc‐loaded whey protein nanoparticles prepared by enzymatic cross‐linking and desolvation

Zinc‐loaded whey protein nanoparticles were prepared by enzymatic cross‐linking whey protein followed by ethanol desolvation. Whey protein isolate (WPI) was denatured by heating (80 °C for 15 min) at pH 7.0 and then cross‐linked by transglutaminase at 50 °C for 4 h while stirring. Transglutaminase was inactivated by heating at 90 °C for 10 min, and then, ZnSO₄·7H₂O (1–10 mm ) was added. Zinc‐loaded whey protein nanoparticles were formed by adding ethanol at one to five times the volume of the protein solution at pH 9.0. The desolvated solutions were diluted by adding distilled water at ratio of 1:100 (w/v) immediately after desolvation. Dynamic light scattering (DLS) data showed that the particle size of zinc‐loaded whey protein nanoparticles increased with the amount of zinc and the volume of ethanol. Scanning electron microscopy micrographs revealed an almost spherical morphology for zinc‐loaded whey protein nanoparticles. The zinc loading efficiency was determined ranging from 76.7% to 99.2%. In vitro test data showed that the zinc release rate was low in simulated gastric fluid but high in simulated intestinal fluid. The results indicated that enzymatic cross‐linked whey protein nanoparticles may be used as a good vehicle to deliver zinc as a supplement.     

Freeze concentration of must in a pilot plant falling film cryoconcentrator

The standard methods of producing concentrated grape must are vacuum evaporation and reverse osmosis. Concentration by freezing is the system that comes closest to the ideal objective of separating water from the food product without affecting the other components. This article examines the process for freeze concentration of white must from Macabeo variety grapes.The pilot plant equipment designed at the Technical University of Catalonia is based on freezing the water content of fluids in direct contact with a cold surface. Different parameters were studied to allow tracking of the process: evolution of soluble solids and the ice production. Freeze concentration tests with forty five litters of must were made at an initial concentration of 16.4 °Brix. A final concentration of 29.5 °Brix was obtained. An average rate of 1.38 °Brix/h was obtained working at flow rates of 0.8 L/s. The ice production ranged from 1.32 to 1.05 g?m^? 2?s^? 1 as the concentration of the must increased.Industrial relevanceSometimes the must has low contents in sugars. The freeze concentration can achieve the appropriate level of concentration in some favorable conditions without losses of aroma and sensorial properties. With this purpose INCAVI (Catalonian Institute of vineyard and wine) provided 100 L of grape juice for the test presented in this article. In this work has been applied this technology to concentrate must (grape juice) obtaining promising results.     

Potassium concentration and pH inter‐relationships in grape juice and wine of Chardonnay and Shiraz from a range of rootstocks in different environments

Background and Aims: pH adjustment during winemaking is a significant cost to the Australian wine industry. This study addresses potassium (K⁺) concentration and pH inter‐relationships in grape juice and wine of Chardonnay and Shiraz. Methods and Results: Chardonnay and Shiraz on own roots, and on Ramsey, 1103 Paulsen, 140 Ruggeri, K51‐40, Schwarzmann, 101‐14, Rupestris St. George and 1202 Couderc were compared at Koorlong and Merbein (Victoria), and Padthaway, Nuriootpa and Rowland Flat (South Australia). Petiole K⁺ concentrations at flowering were a poor indicator of grape juice and wine K⁺ concentrations. The concentration of H⁺ ions in grape juice and wine decreased as K⁺ concentrations increased resulting in increased pH. The relationship between H⁺ and K⁺ concentrations was linear for Chardonnay but exponential for Shiraz, where K⁺ concentrations were higher. Wine K⁺ and grape juice K⁺ concentrations exhibited a positive linear relationship, with slope for Chardonnay about half that for Shiraz, indicating a net loss of K⁺ between grape juice and wine of 58% for Chardonnay and 13% for Shiraz. Conclusions: The study has linked higher wine pH to both higher juice soluble solids and K⁺, and to poorer wine colour hue. Loss of K⁺ during fermentation and cold stabilisation appeared higher for Chardonnay than for Shiraz. Significance of the Study: Rootstocks that lead to lower K⁺ concentrations and pH in grape juice and wine are identified. Differences in the K⁺ concentration dynamics between grape juice and wine of Chardonnay and Shiraz are described and quantified.     

Characterisation of composite edible films based on wheat starch and whey‐protein isolate

Composite films prepared by casting wheat starch and whey‐protein isolate at proportions of 100–0%, 75–25%, 50–50%, 25–75% and 0–100% were characterised. Combination of both substances gave continuous and homogeneous films. The more the starch is in a film, the more dull is the appearance. The highest water adsorption was observed for pure whey‐protein films and the lowest for pure wheat starch films with the final water content of 0.264 and 0.324 g water g d.m.^?1, respectively. An exponential equation well fitted the experimental data of water vapour kinetics (R² ≥ 0.99). The highest values of thickness and elongation at break were observed for films obtained by blending of wheat starch and whey protein. With the increasing content of whey‐protein isolate, the values of the swelling index and tensile strength increased from 34.31% to 71.01% and from 2.29 to 8.90 MPa, respectively. The values of water vapour permeability depended on humidity conditions and decreased slightly with the increasing content of whey‐protein isolate.     

Polyphenol and volatile profiles of pomegranate (Punica granatum L.) fruit extracts and liquors

This work reports on the preparation of new aromatic pomegranate liquors by maceration of pomegranate juice and arils in Arbutus unedo L. distillate. The volatile, anthocyanin and ellagitannin profiles were monitored after each step. Aromatic compounds of pomegranates, such as limonene, 1‐hexenol and trans‐caryophyllene, were detected in trace levels and showed little contribution to the liquor aroma. The main volatiles of the liquors, namely isobutanol, isopentanols, vitispiranes and volatile esters, are given by the fruit distillate. The anthocyanin contents of the pomegranate juice were around 135 mg L^?1 but decreased to about 5% of this value in the final liquors. Anthocyanin diglucoside compounds showed higher stability than their monoglucoside analogs. Punicalagins and punicalins showed contents between 80 and 135 mg L^?1, depending on the used starting pomegranate material. These ellagitannins account for 60% of the total polyphenols. The procedure can be used to prepare aromatic pomegranate liquors with high polyphenol content.     

In‐house validation of a high‐performance liquid chromatography analytical method for quantification of ochratoxin A in unfermented grape juice

A validated high‐performance liquid chromatography (HPLC) method with fluorescence detection for the quantitative analysis of ochratoxin A (OTA) in unfermented grape juice is described. Five millilitres of unfermented grape juice was mixed with 45 mL of PBS, and the pH was adjusted to 7.2. Then the mixture was filtered under vacuum through a glass microfibre filter and cleaned up with immunoaffinity columns prior to analysis by HPLC. Validation of the analytical method was based on the following criteria: selectivity, linearity, limit of detection and quantification, precision (within‐day and between‐day variability) and recovery and uncertainty estimation. Detection and quantification limits obtained were 0.02 µg L^?1 and 0.05 µg L^?1 respectively. The percentage recovery was 91.5% (RSD = 3.9). This method was applied to the measurement of 30 veraison stage unfermented grape juice samples. Copyright © 2007 Society of Chemical Industry     

Investigation on the effects of microwave and conventional heating methods on the phytochemicals of pomegranate (Punica granatum L.) and black mulberry juices

Black mulberry and pomegranate juices were concentrated by conventional and microwave heating at different operational pressures (7.3, 12, 38.5, and 100 kPa). The effects of each heating method on the phytochemical changes (total anthocyanin content and antioxidant activity) of juices were investigated. The effect of various heating methods on the profile of the pomegranate anthocyanins were conducted using high-performance liquid chromatography–mass spectrometry (HPLC–MS). The main anthocyanins of pomegranate quantified by HPLC–MS were cyanidin, delphidin, pelargonidin, 3-glucoside, and 3, 5-diglucoside. In black mulberry juice, the final juice concentration of 42° Brix was achieved in 140, 120, and 95 min at 100, 38.5, and 7.3 kPa respectively and the final pomegranate juice concentration of 40° Brix was achieved in 140, 127, and 109 min at 100, 38.5, and 12 kPa respectively by using a rotary evaporator. Applying microwave energy decreased the required times to 115, 95, and 60 min for black mulberry juice and to 118, 95, and 75 min for pomegranate juice. Results showed that anthocyanin degradation and consequently decrease in antioxidant activity were more pronounced in rotary evaporation compared to microwave heating method.     

Addition of acid whey improves organic dry‐fermented sausage without nitrite production and its nutritional value

In this study, the effect of acid whey on the physicochemical properties and nutritional value of non‐nitrite organic fermented sausage made from beef and tallow was investigated. Fermented sausage was prepared in three formulations: C (cured), S (salted) and SAW (salted with liquid acid whey). Each sample was analysed during the ripening process: at 0, 7, 14 and 21 days of ripening in a temperature of 16 °C. The obtained results indicated that the addition of acid whey improves physicochemical properties of organic dry‐fermented sausage without nitrite and its nutritional value. The application of acid whey resulted in a significantly lower pH and a higher lactic acid bacteria content in organic fermented sausage without nitrite than in the sample with curing salt (respectively, by 0.12 units and 0.66 log CFU g^?1). Acid whey successfully protected against haem iron loss in salted sausage during ripening. The salted sample with acid whey addition was characterised by a higher PUFA content (6.41%) at the end of ripening as compared to the cured sample (4.91%) and salted sample (5.58%). The addition of acid whey improves organic dry‐fermented sausage without nitrite production and its nutritional value.     

Performance on an odor detection and identification test as a predictor of ortho- and retronasal odor intensity ratings in the young and elderly

Two experiments were conducted to examine whether performance on the European Test of Olfactory Capabilities (ETOC, 16 odors to be detected and identified) can predict ortho- and retronasal odor intensity ratings. In Experiment 1 (Exp1), vanilla (0–0.31%) in a beverage (whey drink) was rated for ortho- and retronasal intensity and the ETOC was performed by elderly (n = 27, 66–83, mean 74.4 years) and young (n = 32, 22–36, mean 26.0 years). In Experiment 2 (Exp2), 17 elderly (67–84, mean 74.9 years) and 10 young (22–29, mean 25.9 years) performed the ETOC and rated varying concentrations of vanilla and lemon in aqueous solutions, grape juice and yogurt for ortho- and retronasal intensity. For the young, the mean detection/identification scores of the ETOC were 15.8/14.0 (Exp1), and 15.6/13.2 (Exp2). The corresponding scores for the elderly were 14.6/10.6 (Exp1) and 13.0/7.9 (Exp2).Orthonasally, the young differentiated the aroma concentrations in the whey drinks better than the elderly performing poorly in ETOC. Retronasally, the young and the well performing elderly gave higher intensity ratings for higher concentrations, while the poorly performing elderly were unable to do this. A tendency for small intensity difference in the poorly performing elderly was observed in ortho- and retronasal ratings for aqueous solutions, and orthonasal ratings for grape juice and yogurt. Retronasal intensity ratings of the elderly for grape juice and yogurt were not associated with their ETOC performance. Hence, olfactory performance measured by the ETOC predicted orthonasal intensity ratings, though not evidently, while its predictive ability for the retronasal intensity ratings of the elderly for complex food systems was deficient.     

Ohmic heating assisted vacuum evaporation of pomegranate juice: Electrical conductivity changes

A novel electrical heating method, named as ohmic heating, was successfully integrated to vacuum evaporation system, and pomegranate juice was concentrated until its total soluble dry matter content reached to 40% by applying three different voltage gradients (7.5, 10, and 12.5 V/cm) at 180 mm Hg absolute pressure in this system. Total evaporation times were determined as 152, 78, and 53 min at the voltage gradients of 7.5, 10, and 12.5 V/cm, respectively. The concentration time of pomegranate juice was shortened about 56% by ohmic heating relative to conventional evaporation. The electrical conductivity values were increased up to reach 25% TSDM for 7.5 V/cm and at 35% TSDM for 10 V/cm, then showed a decreasing pattern. However, it was constant (0.55 ± 0.01 S/m) during evaporation process at 12.5 V/cm. It is recommended that the ohmic heating method could be successfully integrated to vacuum evaporation process to shorten the processing time significantly.Industrial relevanceOhmic heating has been utilized as alternative method for the purpose of heating, pasteurization, cooking etc., and relatively better products can be obtained by ohmic heating. Nowadays, energy efficient systems are needed in concentrated juice production. The integration of ohmic heating to the conventional vacuum systems could serve the production high quality juice concentrates with efficient use of energy. In present study, ohmic heating assisted vacuum evaporation of pomegranate juice was conducted, successfully. This method decreased the total process time for juice concentration, which is critically important for industrial scale productions. This novel method can be implemented to the fruit juice production lines by taking into account of design characteristics of ohmic systems such as electrical conductivity changes depending on both temperature and total soluble solids concentration. The effects of main process parameter, named as voltage gradient, on electrical conductivity changes during electrical heating assisted evaporation process has been also reported in the present study.     

Contributions of phenolics and added vitamin C to the antioxidant capacity of pomegranate and grape juices: synergism and antagonism among constituents

The aim of this study was to examine the contribution of sugar, organic acid, neutral phenol, and anthocyanin fractions and added ascorbic acid to grape and pomegranate‐nectarine juice total phenol, oxygen radical absorbance capacity (ORAC), ferric reducing antioxidant power (FRAP) and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) values. Neutral phenol and anthocyanin fractions contributed ≥75% of the total antioxidant capacity (TAC) for both juices. Intrinsic synergy and antagonism among the fractionated constituents occurred inconsistently in each assay. Sugars and organic acids antagonised pomegranate juice neutral phenols and anthocyanins in the DPPH assay by 50% and the grape juice ORAC value by 21%, but were synergistic to the grape juice FRAP value. The added ascorbic acid was dose‐dependently synergistic with pomegranate and grape juice total phenol, DPPH and FRAP assays, but less so in the ORAC assay. Thus, the interactions between grape and pomegranate juice constituents determine TAC and total phenol values, and synergy in these assays could not be attributed solely to polyphenols.     

Freeze‐drying concentration of Rangpur lime juice

The use of freeze‐drying for concentrating lime Rangpur juice was investigated. This procedure allowed obtaining concentrated Rangpur lime juices between 23 and 51.3 °Brix, without affecting their organoleptic and nutritional characteristics. The efficiency of the procedure was inversely related to the film thickness of the matrix to be lyophilised. The sublimation speed per unit area diminished with the reduction in the residual moisture content of the juice. The mathematical model that fitted to the concentration procedure allowed to predict the time required for concentrating Rangpur lime by freeze‐drying starting from samples of different thickness. When compared with other citric juices evaluated, the Rangpur lime juice was the most suitable for freeze‐drying concentration. The results could be used to devise optimal industrial freeze‐drying cycles for processing Rangpur lime juices at different concentrations.     

Application of sepiolite in clarification of pomegranate juice: changes on quality characteristics during process

In this study, for the first time, the function of acid‐activated sepiolite clay was evaluated for clarification of pomegranate juice. The optimum conditions of clarification process were achieved using response surface methodology based on juice turbidity as a response. After that, under optimal condition, efficiency of sepiolite, bentonite and combination of these fining agents with gelatin and kieselgel was compared for clarifying pomegranate juice. The results showed that the best conditions for juice clarification were 0.05% (w/v) clay concentration, temperature of 50 °C and time of 2 h. The results revealed that treatments of bentonite–gelatin–kieselgel and sepiolite–gelatin–kieselgel were the most active fining agents that their use led to a reduction of 99.7% in turbidity of pomegranate juice. Kinetic study for different features was performed, and the results indicated that rate of changes in turbidity, viscosity, total phenolic contents and colour with time followed first‐, first‐, zero‐ and zero‐order kinetic models, respectively.     

Process optimisation of the bitter gourd (Momordica charantia) concentrated juice preparation for a freeze‐dried powder

Bitter gourd (Momordica charantia), a commonly consumed vegetable in South Asia, eastern‐South Asia, China, Japan, Korea peninsula, Caribbean Sea isles etc., is used as an adjunct in the management of diabetes mellitus. In this study, in order to find the effective ways of producing bitter gourd freeze‐dried powder, the concentrated juice of bitter gourd was produced through enzymatic process (EP), ultra filtration (UF), reverse osmosis and vacuum concentration technology. Results indicated that total saponins, total sugar and pH value in bitter gourd juice were almost unchanged after EP and after UF (P ≥ 0.05). However, UF decreased the turbidity and improved transmittance of juice (P < 0.05). When compared with the vacuum concentration alone, the combined process of reverse osmosis followed by vacuum concentration had 3.33 folds of production efficiency and 1.725 times of vitamin C content in concentrated juice. With freeze‐drying microscope system, the eutectic point of the freeze‐dried product of bitter gourd juice was detected to be ?37.5 °C, which was important to optimise lyophilisation parameters. The freeze‐drying microscope system was more accurate than the conventional electric resistance method in detecting the eutectic point of freeze‐dried product.     

Pomegranate (Punica granatum) juices: chemical composition, micronutrient cations, and antioxidant capacity

Abstract: Phenolics, flavonoids, anthocyanins, and tannins of pomegranate juices, obtained from 9 Tunisian ecotypes were quantified. Phenolics and flavonoids in the variety Tounsi (TN) (3299 mg gallic acid equivalents [GAE]/L and 636 mg quercetin equivalents [QE]/L of juice, respectively) were higher than in the variety Gabsi (GB) (1570 mg GAE/L and 135 mg QE/L of juice, respectively). The highest anthocyanins quantity was found in GB 2 with 156 mg cyanidin‐3‐glucoside equivalents (CGE)/L. TN 3 ecotype showed the highest tannins quantity with 2550 mg catechin equivalents (CE)/L of juice. TN 1 presented the highest radical‐scavenging activity (2, 2′‐azinobis‐3‐ethylbenzothiazoline‐6‐sulphonate [ABTS], IC₅₀ [50% inhibition concentration] = 525 mg/L), as well as the highest concentration of micronutrient cations (potassium and sodium). A high correlation (R²= 0.80) between antioxidant capacity and proanthocyanin contents was found, this suggests that proanthocyanins are the principal contributor in the antioxidant capacity of pomegranate. Our data suggest also that the high concentrations of K⁺ and Na⁺ may play a role in the adaptation of pomegranate to arid environments.