Alternative Pressing/Ultrafiltration Process for Sugar Beet Valorization: Impact of Pulsed Electric Field and Cossettes Preheating on the Qualitative Characteristics of Juices

Alternative process of sugar beet transformation is investigated by tuning experimental conditions. A three-step process has been set-up: (1) sugar beet cossettes pretreatment by pulsed electric field (PEF) and (or) short preheating to different temperatures; (2) extraction of juice from pre-treated cossettes by pressing; and (3) purification of the expressed juice by ultrafiltration. The PEF treatment was applied to cold (10 °C) and preheated (to 20, 50, 60, 70, and 80 °C) sugar beet cossettes with intensity of E?=?600 V cm^?1 using rectangular monopolar pulses of 100 μs during t _PEF?=?5–20 ms. Experiments were performed with cossettes of three sizes. Control experiments were done without PEF treatment using cold (10 °C) and preheated (to 20–80 °C) cossettes. PEF-treated and (or) preheated cossettes were pressed at 5 bars during 15 min. Afterward, expressed juices obtained from the PEF-treated cossettes at 20 °C and from the untreated ones at 80 °C were purified by dead-end ultrafiltration with stirring (500 rpm) at the temperature of 20 °C by using polyethersulfone membrane with MWCO of 30 kDa. Application of PEF (E?=?600 V cm^?1, t _PEF?=?10 ms, T?=?20 °C) with following pressing of cossettes at 5 bars during 15 min permits to obtain the juice yield Y?=?66,5 %, which is equivalent to that obtained from cossettes preheated to 80 °C and untreated electrically (Y?=?64 %). The energy consumption of cold PEF treatment (≈2–3 Wh/kg) is very attractive as compared to preheating at high temperatures (≈138–194 Wh/kg). Combination of thermal and electrical pretreatments leads to additional softening of sugar beet tissue and to a slightly higher (on 5–10 %) juice yield, but the electroporation of preheated cossettes is more energetically costly. The raw juice expressed from PEF-treated cossettes at 20 °C has higher purity (93.5 %) than juices expressed at 50 °C (92.9 %) and at 80 °C (92.3 %). The temperature increasing from 20 to 80 °C results in a higher juice coloration (5680 IU at 20 °C and 7820 IU at 80 °C) and leads to a higher (on about 35 %) colloids concentration in the expressed juice. The filtrate obtained from the juice expressed at 20 °C with PEF treatment has a higher purity (96 %) than the filtrate obtained from the juice expressed at 80 °C (95.3 %) and its coloration is considerably lower (330 IU versus 1930 IU). In addition, the quantity of proteins and colloids in the filtrate of juice expressed at 20 °C is lower than that in the filtrate of juice expressed at 80 °C     

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.     

Spray-Drying of Probiotic Cashew Apple Juice

Data on spray-drying of fruit juices containing probiotic bacteria are scarce. The main challenge is to avoid the viability losses of the microorganism during drying and storage. In the presented study, the dehydration by spray-drying of cashew apple juice containing Lactobacillus casei NRRL B-442, and the influence of the storage temperature (25 and 4 °C) on the viability of L. casei NRRL B-442 and on the physical properties of the powder during 35 days of storage were evaluated. Probiotic cashew apple juice was dehydrated according to the following conditions: inlet temperature of the drying air (120 °C), feed flow rate of juice (0.3 L/h), hot air flow (3.0 m³/min), and pressurized air flow (30 L/min). The outlet temperature was 75 °C. The carriers used were 20 % (w/v) maltodextrin or 10 % (w/v) maltodextrin + 10 % (w/v) gum arabic. Microbial survival rates higher than 90 % were obtained for the powder stored at 4 °C for 35 days (both carriers) and higher than 70 % up to 21 days for the powder obtained using only maltodextrin at 25 °C. Higher yields were obtained only by maltodextrin which was used as carrier (72 %) compared to the yield obtained when the mixture of maltodextrin and gum arabic was applied (60 %). The water activity was kept low (Aw?<?0.30) during the storage, and the characteristic color of the product was maintained.     

Pressure-Thermal Kinetics of Furan Formation in Selected Fruit and Vegetable Juices

Furan, a potential carcinogenic compound, can be formed in array of processed foods. The objective of this study was to conduct kinetic studies in pineapple juice and assess the interactive effects of pressure (0.1 to 600 MPa) and temperature (30 to 120 °C) on furan formation. Additional experiments were carried out in tomato, watermelon, cantaloupe, kale, and carrot juice to understand the influence of matrix and juice pH. Furan was monitored in raw (control) and processed samples by automated headspace gas chromatography mass spectrometry, and quantified by calibration curve method with d₄-furan as internal standard. The data were modeled using zero-, first-, and second-order equations. The zero-order rate constants (k _T,P ), activation energy (E _a ), and Gibbs free energy of activation (ΔG ^?) of furan formation in thermally processed (TP; 90–120 °C) pineapple juice were found to be 0.036–0.55 μg/kg/min, 98–114 kJ/mol, and 173.9–180.5 kJ/mol, respectively. Furan concentration was negligible and close to the detection limit (0.37 μg/kg) after pressure treatment (600 MPa at 30 °C) of juice samples. For similar process temperatures, the rate constants of pressure-assisted thermally processed (PATP; 600 MPa at 105 °C) pineapple juice were lower than that of TP samples. Furan formation was influenced by juice matrix and pH. On the other hand, PATP markedly suppressed furan (0.7 to 1.6 μg/kg) in these selected juices. In conclusion, furan formation increased with process temperature and treatment time, while pressure treatment at ambient temperature did not promote its production. Furan formation in TP fruit juices was also influenced by juice matrix and pH, but these were not the significant factors for PATP-treated juices.     

Inactivation Kinetics of the Most Baro-Resistant Enzyme in High Pressure Processed Litchi-Based Mixed Fruit Beverage

This work focused on a litchi-based mixed fruit beverage, comprising of coconut water and lemon juice, mixed in an optimized proportion. Based on preliminary studies, three resistant spoilage enzymes were identified in the beverage, viz. polyphenol oxidase (PPO), peroxidase (POD), and pectin methyl esterase (PME). The response surface methodology (RSM) based on central composite face-centered design (FCCD) screened out PPO as the most resistant enzyme within the high pressure processing (HPP) domain of 200–600 MPa/30–70 °C/0–20 min. A detailed kinetic study was conducted on PPO inactivation within the same HPP domain along with a set of thermal treatments (0.1 MPa/30–70 °C). A synergistic effect of pressure and temperature on PPO inactivation was observed, throughout the HPP domain. However, PPO was almost completely inactivated at 500 MPa/70 °C/20 min. The inactivation order (n) values for PPO were 1.10 and 1.25 for thermal and HPP treatments, respectively. For every 10 °C rise in temperature, the inactivation rate constant (k, U^n-1 min^?1) increased approximately by 1.5 times, within 50–70 °C (at 0.1 MPa), while a 10-fold increase was obtained in the case of HPP treatments. The activation energy (E _a ) and the activation volume (V _a), depicting the temperature and pressure dependence of k, was found to decrease slightly, with an increase in pressure and temperature, respectively. The PPO inactivation rate constant was modeled as a function of both temperature and pressure conditions by combining both Arrhenius and Eyring equations.     

Heat Induced Browning of Clarified Apple Juice at High Temperatures

A procedure to determine deterioration reaction kinetics of fluid foods at elevated temperatures is described. With this method the nonenzymatic browning (NEB) measured as O.D. at 420 nm of Red Delicious (RD) and Granny Smith (GS) apple juices was examined. Color development at 15°, 30°, 50°, and 70° Brix and temperatures ranging from 90–108°C were compared over 60 min. Results indicated an apparent first order reaction rate depending on temperature, apple juice composition and soluble solids. Browning occurred at a more rapid rate in GS juice. NEB reaction rate was shown to depend critically on the total amino acid content. Temperature dependence followed the Arrenhius equation and the activation energy (E_a) ranged from 22.0–24.8 Kcal/mole.     

Pilot scale inulin extraction from chicory roots assisted by pulsed electric fields

A pilot study for the pulsed electric fields (PEF) assisted countercurrent diffusion of inulin from chicory roots is presented. The influence of PEF parameters (electric field intensity E = 600 V cm^?1, treatment duration t_PEF = 10–50 ms) and diffusion temperature (varied between 30 and 80 °C) on soluble matter extraction kinetics, inulin content of juice, and pulp exhaustion are investigated. The draft (liquid to solid mass ratio) was fixed at 140%, similar to the industrial conditions. PEF treatment facilitates extraction of inulin at conventional diffusion temperature (70–80 °C), and diffusion temperature can even be reduced by 10–15 °C with comparable juice inulin concentration. Less energy consumption can be achieved by reducing PEF treatment duration to 10 ms, which is observed sufficient for effective extraction.     

Rheological and Chemical Characterization of Smoothie Beverages Containing High Concentrations of Fibre and Polyphenols from Apple

Beverages are an ideal food format to deliver health-promoting polyphenols (PPs) and dietary fibres (DFs) to consumers. In this study, complex beverage systems, smoothies, were formulated containing high concentrations of apple PPs (500 mg per 300 ml beverage), apple fibres of two different particle sizes (AF01, 250 μm; AF09, 300–700 μm; each containing soluble and insoluble fibres), and stabiliser carboxymethylcellulose (CMC; 0.05–2.00 %). The beverages were pasteurised at 85 °C for 15 s, and subjected to total extracted PP content (TEPC) and rheological measurements (viscosity, elastic modulus G′ and viscous modulus G″ at 4, 20, 37 and 60 °C). Scanning electron microscopy (SEM), FT-IR spectroscopy and N₂ physisorption measurements on the AF01 and AF09 fibre powders showed that they differed in particle size, yet were similar in particle surface morphology, chemical composition and specific surface area. Characterisation of smoothies prepared from the AF01 and AF09 fibres showed that the particle size of the apple fibres, testing temperature and CMC concentration strongly influenced the extractability of PPs and rheological behaviour of the smoothies. The peak TEPC values of the AF01 and AF09 beverages, 327 and 351 mg catechin equivalent per 300 ml beverage, occurred at 1.50 % and 1.00 % CMC, respectively. The temperature dependence of smoothie viscosity was examined, and an Arrhenius relationship was observed for both the AF01 and AF09 smoothie systems. The stabilising effect of CMC for this type of smoothie beverage was confirmed. CMC concentrations of 1.00–1.50 % afford high extracted PP content, good phase stability and beverage flow properties. These results presented here can be used to guide the development of stable beverages containing relatively high concentrations of PPs and DFs (including both insoluble and soluble).     

Isolation, purification and determination of some biochemical properties of β-glucosidase from Muscat of Bornova grape

This research was undertaken to determine biochemical properties of β-glucosidase (β-d-glucoside glucohydrolase, EC 3.2.1.21) isolated from Muscat of Bornova grape. The optimum pH for β-glucosidase activity was found to be 5.0, and the enzyme showed high activity over a broad pH range of 4.5–6.0. However, due to low activity at pH 3.0, the enzyme is expected to exhibit only a fraction of the maximum activity during grape juice fermentation due to low pH of grape juice. As the temperature increased from 30 to 55 °C, the activity increased, too, the maximum activity occurring at 55 °C which implies that the enzyme is expected to exhibit a low activity at grape juice fermentation. According to thermal inactivation studies, k _D values increased as the temperature increased, whereas half-life and D values decreased. Energy of activation (E _a) and Z values were found to be 120.99 kj mol^?1 (r ² = 0.9776) and 18.08 °C (r ² = 0.9750), respectively. d-glucose and ethyl alcohol inhibited the enzyme at varying degrees depending on the concentration.     

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.     

Heat resistance of the spoilage yeastsCandida pelliculosaandKloeckera apisand pasteurization values for some tropical fruit juices and nectars

Spoilage yeasts, identified asCandida pelliculosaandKloeckera apis, were isolated from fermented pasteurized pineapple juice, guava and passion fruit nectars, and studied for their heat resistance in relation to the pasteurization process of the beverages. The decimal reduction times (D_T) obtained between 55 and 60^°C forK. apisvaried from 1.41 to 2.49 min, and those forC. pelliculosaobtained between 60 and 75^°C varied from 1.03 to 4.90 min depending upon the beverage and the tested temperatures.C. pelliculosaseemed to be more heat resistant thanK. apis. Thez-values or the increase in temperature needed to reduce theD_Tby 10, determined between 60 and 75^°C forC. pelliculosa, were 31.75±0.03^°C (r²=0.91) in pineapple juice, 27.70±0.04^°C (r²=0.90) in passion fruit nectar and 34.84±0.02^°C (r²=0.998) in guava nectar. ForK. apis, thez-values determined between 55 and 60^°C were 21.88±0.07^°C (r²=0.97) in pineapple juice, 22.73±0.04^°C (r²=0.99) in guava nectar and 29.07±0.01^°C (r²=0.999) in passion fruit nectar. The minimal pasteurizing valuesP_T^zwere determined forC. pelliculosaat 70^°C and at 75^°C, at a pasteurization efficiency (logN₀/N) of 9. In pineapple juice,P^z₇₀=27.91 min andP^z₇₅=13.5 min would have be applied to destroy almost any vegetative forms of the yeast. In passion fruit nectar,P^z₇₀=20.25 min andP^z₇₅=9.27 min, and in guava nectarP^z₇₀=16.83 min would have be applied.     

Growth inhibition and inactivation of Alicyclobacillus acidoterrestris endospores in apple juice by hyperbaric storage at ambient temperature

Control of endospores of Alicyclobacillus acidoterrestris in pasteurized apple juice using hyperbaric storage at 18 to 23 °C was compared to storage at atmospheric pressure and 18 to 23 °C, as well as refrigeration at ~4 °C for up to 30 days. The juice samples were inoculated with approximately 1 × 10⁵ CFU/mL spores. The juice spoiled quickly at atmospheric pressure and ambient temperature, while under refrigeration spore levels remained unchanged for 30 days. Hyperbaric storage of inoculated apple juice at 25, 50 and 100 MPa at 18 to 23 °C resulted in spore inactivation at more rapid rates as pressure magnitudes increased, reaching levels below the detection limit of 10 CFU/mL at 50 and 100 MPa. In highly acid foods such as apple juice, hyperbaric storage at pressures ≤100 MPa and ambient temperature was effective in inactivating spores of A. acidoterrestris for periods up to 30 days.These results indicate hyperbaric storage at ambient temperature as a clearly more efficient preservation procedure to control the development of A. acidoterrestris endospores, compared to ambient temperature and refrigerated storage, in highly acidic foods as apple juice.     

Synthesis of octadecyl acrylate-co-ethylene glycol dimethacrylate resin for removal of dark-colored compound from apple juice and comparison with polyvinylpolypirrolidone (PVPP)

Adsorption process has an importance for improving the color of juice and also stabilizing the final product during the shelf life. In this study, polyvinylpolypirrolidone (PVPP) and octadecyl acrylate-co-ethylene glycol dimethacrylate (ODA-EGDMA) polymeric resins were used as adsorbents for improving the color properties of apple juice. The ODA-EGDMA resin was prepared by classical suspension polymerization technique and characterized by electron microscopy. The obtained spherical particles diameters were between 20 and 140 μm. PVPP was selected as reference polymeric material for its importance in the juice industry. The adsorption kinetics of dark-colored compounds on adsorbent polymeric resins were studied at different adsorbent resins concentrations (1, 2, 4, and 8 g adsorbent resin per liter of apple juice) at the constant temperature (20 °C) in batch reactor. Langmuir adsorption model was applied for both PVPP and ODA-EGDMA polymeric adsorbents. The Langmuir isotherms were plotted for both polymeric adsorbents by evaluation of the absorbance data of apple juice at 420 nm. Langmuir isotherm's empirical constants known as K _ad and Q ₀ were calculated from the equilibrium data. Numerical value of K _ad and Q ₀ were determined as 5.0578 and 0.3089 for the ODA-EGDMA polymeric resin, 2.4824 and 0.5268 for the PVPP adsorbent, respectively. The scope of this study included comparison of reusability and regeneration properties of the each polymeric adsorbent. For this purpose, series of experiment were done in pack bed column application. Pressure drop measured throughout the PVPP pack bed column was 4.8 times higher than ODA-EGDMA pack bed column at same flow rate (2.5 mL/min) during the this group experiment. ODA-EGDMA resin and PVPP were regenerated with NaOH (4% w/v, 50 °C) after each run. After regeneration, average removal of dark color (relative absorbance change at 420 nm) of apple juice was determined as 76.47±0.90% for ODA-EGDMA and 91.51±0.86% for PVPP adsorbent resin.     

Response Surface Methodology Study for Optimization of Effects of Fiber Level, Frying Temperature, and Frying Time on Some Physicochemical, Textural, and Sensory Properties of Wheat Chips Enriched with Apple Fiber

In this study, wheat chips enriched with apple fiber were produced, and response surface methodology was used for the determination of the simultaneous effects of processing variables selected as fiber level (0–15 %), frying temperature (160–180 °C), and frying time (40–60 s) on some physicochemical, textural, and sensorial properties of chips. Ridge analysis was conducted to determine the optimum levels of processing variables. Predictive regression equations with high coefficient of determination (R ²?≥?0.728) were constructed. Addition of apple fiber increased the dry matter; ash content; L, a, and b values of samples, while increase of frying temperature caused decrease of the hardness values. Overall acceptability of chips enriched with apple fiber decreased with the increase of frying temperature, but wheat chips enriched with apple fiber and fried at low temperatures received highest sensory score. Ridge analysis showed that maximum taste score would be attained at fiber level?=?15 %, frying temperature?=?170 °C and frying time?=?40 s.     

Ultrafiltration and reverse osmosis for clarification and concentration of fruit juices at pilot plant scale

The process of ultrafiltration of raw juices (peach, pear, apple and mandarin) through tubular polysulphone membranes (8 kDa) and finally concentrated by reverse osmosis membranes of tubular composite polyamide film (99 g/100 g NaCl rejection) with filtration area of 0.9 m² was studied. Furthermore, in order to obtain a higher permeate flow, the fluids were previously treated with commercial pectinolytic enzyme.The following parameters were analyzed: permeate flow, soluble solids, viscosity, density, pH, acidity, formol index, starch, pulp content, color and presence of pectin. The use of a pectinolytic enzyme provides increased permeate flux of approximately 40%, retaining the juice properties. The highest total soluble solids content was clarified peach juice from 12.2 °Brix concentrated up to 30.5 and 21.52 °Brix by using RO with transmembranes pressures of 4 and 2 MPa respectively.The results show a cross-flow velocity (1.8 m/s) which corresponds with Reynolds number that is on the lower border of a laminar flow and above of transition rate (2090 < Re < 2900). Also the (VCF) for mandarin (1.49), pear (1.53), apple (1.56) and peach (1.58) was obtained for RO process. The membranes used were characterized morphologically using scanning electron microscopy.     

Changes in Quality and Nutritional Parameters During Refrigerated Storage of an Orange Juice–Milk Beverage Treated by Equivalent Thermal and Non-thermal Processes for Mild Pasteurization

The effects of high-pressure (HP) treatment (400?MPa at 42 °C for 5 min) and pulsed electric field (PEF) processing (25 kV/cm at 57 °C for 280 μs) on ascorbic acid, total carotenoids, total phenolic compounds and total antioxidant capacity (TEAC and ORAC) of an orange juice–milk (OJ-M) beverage along the storage time at 4 °C were compared with a conventional heat preservation technology used in industry (90 °C for 15 s). During storage, ascorbic acid, total carotenoids and antioxidant capacity (TEAC) depleted with time regardless of the treatment applied. Instead, total phenolic content and antioxidant capacity measured by the ORAC method increased at the end of the storage. Non-thermal-treated beverage had less non-enzymatic browning than the thermally pasteurized one. There were no significant variations in the hidroxymethylfurfural (HMF) content of the HP- and PEF-treated OJ-M, whilst a significant increase was obtained after thermal treatment. During refrigerated storage, HMF was always below the maximum values established. The HP treatments reduced the L* value of the treated beverages immediately after processing and during refrigerated storage and induced an increase in total colour differences of beverages treated by HP compared with PEF and thermally processed orange juice–milk. Hence, alternative methods such as HP and PEF may give new opportunities to develop orange juice–milk with an equivalent shelf life to that of thermally treated orange juice mixed with milk in terms of microbial, physicochemical and nutritional characteristics.     

Optimization of Covalent Immobilization of Extracellular Ice Nucleators from Erwinia herbicola on Magnetic Fe3O4/Chitosan Nanoparticles for Potential Application in Freeze Concentration

A magnetically separable extracellular ice nucleators (ECINs) immobilized system was constructed, ECINs from Erwinia herbicola were covalently immobilized on magnetic Fe₃O₄/chitosan nanoparticles by coupling via glutaraldehyde (GA) or epichlorohydrin (ECH). The immobilization process parameters were optimized, and under optimized conditions, ice nucleation activity (INA) of GA and ECH immobilized ECINs reached at 1.56?×?10⁶?±?1.54?×?10⁵ Units/mg and 1.62?×?10⁶?±?1.91?×?10⁵ Units/mg, respectively. The stability, reusability and cytotoxicity of GA and ECH immobilized ECINs were characterized and compared; both GA and ECH immobilized ECINs demonstrated good reusability performance after 15 freeze–thaw cycles and low cytotoxicity, while GA immobilized ECINs were recovered more easily and more stable at different pH compared to ECH immobilized ECINs. Application of the immobilized ECINs in freeze concentration was investigated, and an increase of ice nucleation temperature for water, seawater and apple juice (6.83?±?0.18 °C, 8.08?±?0.50 °C and 9.38?±?1.12 °C) was achieved by using GA immobilized ECINs. The results collected so far show that there are extensively promising applications for GA immobilized ECINs in freeze concentration industry fields.     

Evaluation of Microbial Stability,Bioactive Compounds,Physicochemical Properties,and Consumer Acceptance of Pomegranate Juice Processed in a Commercial Scale Pulsed Electric Field System

This paper investigated the feasibility for pasteurizing raw (100 %) pomegranate juice in a commercial scale pulsed electric field (PEF) processing system. The juice was processed at 35 and 38 kV/cm for 281 μs at 55 °C with a flow rate of 100 L/h. Effect of PEF processing on microbial stability, color, °Brix, pH, sediment, antioxidant activity, total phenolic content, anthocyanin, and sensory properties after the treatments and during storage at 4 °C for 12 weeks were studied and compared to those of thermally processed juice. PEF treatments significantly (p?<?0.05) inhibited the growth of total aerobic bacteria, which remained at <2.5 log colony-forming units (CFU)/ml during the 12-week storage. No yeast and mold were detected (<0.69 log CFU/ml) in the PEF-treated juices during storage up to weeks 10 and 12, which is similar to the thermally processed juice. There were no significant differences in pH and °Brix values between the PEF processed juice and unprocessed juice. PEF processing did not alter the contents of total phenolics and anthocyanin as compared to unprocessed juice. PEF processing had significantly (p?<?0.05) less impact on the color of pomegranate juice than thermal processing. PEF-treated juice had the same consumer satisfaction scores as the unprocessed juice, which were significantly (p?<?0.05) higher than thermally processed juice samples. There was no significant difference between the two PEF treatments in all results. This study demonstrated that PEF technology extended microbial shelf-life and preserved the major quality and nutritional characteristics of pomegranate juice, and hence, is technically feasible for commercialization in the juice industry.     

Storage Stability and Acceptance of Probiotic Beverage from Cashew Apple Juice

The stability of nonfermented cashew apple juice (control) and the fermented juice with Lactobacillus casei NRRL B-442 (sweetened and nonsweetened samples) was investigated along the storage at 4 °C for 42 days. The viability of the probiotic bacteria, sugars, lactic acid, and vitamin C content besides color, antioxidant activity, enzyme activity, and sensory characteristics of probiotic cashew apple juice was evaluated. It was observed that viable cell counts increased in the probiotic cashew apple containing sucrose (8 % w/v) along the storage period. Viable cell counts were always higher than 8.00 Log CFU/ml throughout the storage period. Ascorbic acid loss was higher in the nonfermented juice (40 %) compared to the fermented juice (23 %). The same behavior was observed for antioxidant activity and total polyphenolic compounds content, conferring nutritional benefits to this functional food. Browning reactions and nutritional breakdown caused by enzymes were minimized in the fermented samples during storage. In the fermented sample, higher reduction (>70 %) in the polyphenol oxidase enzyme activity was observed. During storage, the increase in the chroma values from 3.2 to 5.0 indicated that the yellow color became more vivid. Sensory analysis of the fermented cashew apple juice revealed that the product was well-accepted, with acceptance percentages above 80 % for the sweetened juice at the end of the storage period.     

Storage stability of a tropical fruit (cashew apple,acerola, papaya,guava and passion fruit) mixed nectar added caffeine

Nectars are formulated beverages with a fruit juice or pulp as its main component. A blend of fruits can also be used, with the advantage of combining sensory and nutritional properties of different fruits. The beverages may be added with some energetic component, as caffeine, known by its stimulating effect on central nervous system. The objective of this study was to develop mixed nectar of cashew apple, papaya, guava, acerola fruit and passion fruit added caffeine. The beverage was prepared with 35% juice blend and 10% sugar, added with 100 mg of caffeine L^?1 and 60 mg of sodium metabisulfite (SO₂) L^?1 and 500 mg of sodium benzoate L^?1 as preservatives, packed in cleaned pasteurised bottles and heat processed at 90 °C for 30 s. Physicochemical, microbiological and sensory analyses of the beverage were performed initially (time zero) and during 6 months of storage at room temperature (about 25 °C). The products were microbiologically stable during storage. The vitamin C content decreased significantly throughout storage time, although it has remained relatively high. The product presented good sensory acceptance, which suggests its potential for market.