Optimising enzymatic maceration in pretreatment of carrot juice concentrate by response surface methodology

In this paper, enzyme preparation for carrot pulp maceration was screened out and enzymatic maceration processing condition of the carrot pulp was optimised by response surface methodology for carrot juice concentrate. Pectinex Smash XXL was the best commercial enzyme preparation than Pectinex Ultra SP‐L, Pectinase FNP‐1 and cellulose FNC‐1 employed in the carrot juice processing in the study. The effect of enzyme concentration and incubation time and their complex interaction on juice β‐carotene content, juice yield and viscosity in the maceration process was studied by using experiments of central composite rotatable design. The results indicated that under the optimal conditions that the enzyme concentration was 100 mL t^?1 and incubation time was 80 min, the juice β‐carotene content was ≥54.2 mg kg^?1, the juice yield ≥63.5% and the juice viscosity ≤2.1 mPa S.     

Process for the recovery of a carotene-rich functional food ingredient from carrot pomace by enzymatic liquefaction

A novel process for the recovery of a carrot pomace hydrolyzate rich in carotene was developed on pilot plant-scale. The process includes techniques of fine grinding, enzymatic hydrolysis, finishing, homogenization, and concentration. An extensive optimization of the enzymatic hydrolysis on a laboratory scale was performed before scaling up. An enzyme mixture composed of pectolytic and cellulolytic activities at a 1:1 ratio achieved the best degradation, and with a dosage of 1500 ppm at 50 °C and pH 4, the hydrolysis time was reduced to 1 h on pilot plant-scale. Total carotene content (α- and β-carotene) of the concentrated hydrolyzate (3.8 °Bx) was 64 mg per kg.     

Optimisation of enzymatic liquefaction of mango pulp by response surface methodology

 Enzymatic liquefaction of the Neelam variety of mango pulp has been optimised by response surface methodology. The effect of enzyme concentration and incubation time and their complex interaction on juice yield, clarity of the juice, alcohol-insoluble solids and viscosity of the mango pulp have been studied using a central composite rotatable design of experiments. The results showed that at the optimum condition (enzyme concentration and incubation time of 0.14% and 46.67 min, respectively) the yield was ≥64%, clarity ≥71%, alcohol-insoluble solids ≤2.0% and viscosity ≤1850 cP. Received: 28 May 1998     

Pressure and temperature stability of water-soluble antioxidants in orange and carrot juice: a kinetic study

The stability of water-soluble antioxidant in orange and carrot juice was studied on a kinetic basis during thermal (75–120 °C) and high pressure (100–800 MPa; 30–65 °C) treatments. The water soluble antioxidant capacities of both orange and carrot juice, determined using the TEAC number, increased for the first 60 min and 90 min of thermal treatment respectively. These increases can be described by a first order reaction model. The increases in antioxidant capacity became sharper as the temperature was increased, and the estimated Ea values were 79.00±7.83 and 40.46±8.43 kJ mol^–1 respectively for orange and carrot juice.During the high pressure treatments, a decrease in TEAC number was noticed for the antioxidant capacity of orange juice, and an increase in TEAC number for carrot juice. A first order reaction model was applied to estimate the rate constants. At all of the temperatures studied, the antioxidant capacity of orange juice decreased more quickly as the pressure was increased. On the other hand, the increase in the antioxidant capacity of carrot juice was slowed down by a pressure increase at temperatures above 40 °C.     

Changes in carotenoids including geometrical isomers and ascorbic acid content in orange–carrot juice during frozen storage

Fruits and vegetables are highly perishable foods, which explains the need to apply preservation techniques, such as freezing. The aim is to combine shelf life extension with maintenance of sensory and nutrient characteristics. The stability of orange–carrot juice stored at –40 °C for 132 days was studied. The ascorbic acid and carotene contents and the influence of storage time were analysed. Carotenes were identified and quantified by liquid chromatography and ascorbic acid was determined by differential pulse polarography. The initial concentration of ascorbic acid was 27.09 mg/100 ml and decreased by 4.1% during the storage period. Vitamin A activity in the orange–carrot juice increased during the period studied, fitting a linear model (R²=0.87). Of the 14 carotenes identified, only antheraxanthin and the mixture of 9-cis-violaxanthin and neoxanthin decreased in concentration during the storage period.     

Loss of rutin and antioxidant activity of asparagus juice caused by a pectolytic enzyme preparation from Aspergillus niger

We found that a commercial pectolytic enzyme preparation from Aspergillus niger (pectinase AN) contained laccase activity that decreased rutin content and antioxidant activity of asparagus juice. This research investigated the effects of pH, temperature, and concentration of pectinase AN on pectinase AN’s laccase activity to decrease rutin content and antioxidant activity of asparagus juice. Asparagus juice was incubated with pectinase AN at different pHs (3.2, 4.5 and 5.8), temperatures (25, 37, and 50 °C) and enzyme concentrations (0.1%, 0.5% and 1%). Rutin content and antioxidant activity of samples was determined by HPLC and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) free radical method, respectively. The rate of loss of rutin and antioxidant activity of asparagus juice was smaller at pH 3.2 than at pH 4.5 and pH 5.8, smaller for 0.1% pectinase AN than 0.5% and 1% pectinase AN. The rate of loss of rutin of asparagus juice was greater at 25 °C than at the other two temperatures. Pectinase AN can decrease rutin content and antioxidant activity of asparagus juice at the selected conditions. But rutin content and antioxidant activity of asparagus juice produced using pectinase AN could be less decreased at pH 3.2 and 0.1% of enzyme with less than 2 h of incubation time. This information was helpful for juice industry to produce juices with high antioxidant activity using pectinase AN.     

Optimising clarification of carrot juice by bacterial crude pectinase

This study was undertaken to search for potential use of crude bacterial pectinase enzyme produced from Bacillus subtilis grown on hazelnut shell hydrolysate in clarification of carrot juice and to optimize the enzyme load, pH and time using the Box–Behnken response surface methodology (RSM). The carrot juice was treated with the crude pectinase enzyme (5.60 U mL^?1) at different concentrations (0.1–0.5%), pH (4–7), and time (2–6 h). The obtained enzyme was also compared with commercial fungal pectinase at identical conditions. RSM provided optimal clarification conditions of 0.5% (w/v) enzyme load, 7.0 pH, and 6 h of time estimating 100% clarity, whose experimental counterpart was 94.47 ± 0.01%. High values of coefficient of determination (R² = 0.9631), predicted R² (0.8989) and insignificant lack‐of‐fit (0.12) also showed that the model was successful in predicting % clarity for various combinations. This study also indicated that crude bacterial pectinase providing about 95% clarity is superior to commercial fungal pectinase, which gave 78% clarity under tested conditions, in terms of clarification ability for carrot juice.     

THE EFFECT OF ENZYMATIC MASH TREATMENT, PRESSING, CENTRIFUGATION, HOMOGENIZATION, DEAERATION, STERILIZATION AND STORAGE ON CARROT JUICE

The enzyme preparation Pectinex Smash XXL was employed to macerate the carrot pulp, the effect of enzymatic mash treatment (EMT), pressing, centrifugation, homogenization, deaeration, sterilization and storage on carrot juice was investigated. As compared with the control sample, an increase of juice yield, total soluble solid (TSS) and carotenoids in carrot juice was close to 20%, 1% and 26 mg/kg, respectively, after EMT. The EMT also increased the color parameters CIEL*, a*and C*values in carrot juice. However, it significantly decreased the viscosity from 2.54 to 2.09 mPa·s. The centrifugation resulted in a significant decline in turbidity from 240.33 to 187.33 NTU and a significant increase in the color parameters in carrot juice. After homogenization, the turbidity and the carotenoids in carrot juice were significantly reduced from 187.33 to 161.67 NTU and from 61.87 to 58.76 mg/kg, respectively. The turbidity and carotenoids in carrot juice decreased during storage, and all the color parameters had a closer relationship with storage temperature and time; higher storage temperature and longer storage time caused greater loss of color.     

不同酶制剂对胡萝卜汁理化指标的影响效果

研究了酶制剂对胡萝卜原料的出汁率和胡萝卜汁中可溶性固形物、粘度、浊度、类胡萝卜素含量等指标的影响。结果表明 ,经过酶液化后可提高出汁率、可溶性固形物 ,而粘度与浊度有所下降 ;与其他酶处理和对照相比 ,果胶酶A可显著提高类胡萝卜素含量 ,达到 69 1 2mg/kg ,而产品粘度和浊度变化最小 ,分别减少了 0 5 4mPa·s和 1 5NTU ,冷藏 1周后胡萝卜汁仍保持良好的橙红色和混浊稳定性 ,无澄清     

Effect of enzymatic hydrolysis on the yield of cloudy carrot juice and the effects of hydrocolloids on color and cloud stability during ambient storage

The color and cloud stability of cloudy carrot juice were improved by enzymatic hydrolysis and addition of hydrocolloids. Cellulytic and pectolytic enzyme preparations were used to prepare the carrot juice and their optimum dosages were 1.6 g kg^?1 and 0.035 g kg^?1, respectively. Hydrocolloids including guar gum, pectin and flaxseed gum were each added to the carrot juice and assessed for their ability to stabilize the carrot juice. Pectin had no effect on the cloud stability of carrot juice. Guar gum and flaxseed gum stabilized the cloudy carrot juice owing to macromolecular steric repulsion, while flaxseed gum reduced the creaming of cloudy carrot juice owing to its emulsification. The color and β‐carotene content of carrot juice did not change during 6 months of storage. Copyright © 2004 Society of Chemical Industry     

Enzymatic hydrolysis of carrot for extraction of a cloud-stable juice

The influence of various enzymes on the cell wall structure of carrots (Daucus carrota) was examined and related to changes in the juice extracted from the pulp with respect to volume, solids content, pH and viscosity. Crude preparations of cellulase (EC 3.2.1.4), hemicellulase, pectinase (EC 3.2.1.15), pectinesterase (EC 3.1.1.11) and an industrial grade pectinase/cellulase preparation (Rohament PC), all exhibiting cellulolytic as well as pectinolytic action, were used either singly or in combinations. Polarizing microscopy revealed a gradual loss of birefringence from the cell walls indicating degradation of ordered structure by all of the enzymes. The time for loss of birefringence was significantly correlated with the pectinase activity but not with the cellulase activity, suggesting that the presence of pectic substances is important in maintaining the ordered structure of the cell wall in carrot. Alterations to cell wall structure by pectinase were confirmed by scanning electon microscopy. Hydrolytic activity against carrots as measured by the increase in yield of juice could be predicted from the pectinase and cellulase activities through a linear regression equation (R = +0.72; P < 0.01) but the pectinolytic action was the most important factor. The yield of juice from the control carrot was 50.5% of the wet pulp mass with a total solids content of 7.9%, viscosity of 2.9 centistokes and a pH value of 5.65. Application of the enzyme preparations to the pulp (268–455 mg/kg) increased the volume of juice extracted, with the industrial grade preparation (440 mg/kg) yielding 50% more juice than the control for a 30-min incubation at 50 °C.     

Optimization of Enzymatic Hydrolysis Pretreatment Conditions for Enhanced Juice Recovery from Guava Fruit Using Response Surface Methodology

The effect of enzyme concentration (0.16–0.84 mg/100 g guava pulp), incubation temperature (36.6–53.4 °C), and incubation time (0.95–11 h) on juice yield was studied. A central composite rotatable design was used to establish the optimum conditions for enzymatic hydrolysis of guava to obtain maximum juice yield. Significant regression model describing the changes of juice yield with respect to hydrolysis parameters were established with the coefficient of determination, R ² = 0.85. Enzyme concentration was the most significant variable affecting the juice yield. The recommended enzymatic treatment condition from the study was at the enzyme concentration 0.70 mg/100 g guava pulp, incubation time 7.27 h, and incubation temperature 43.3 °C.     

PRODUCTION AND USE OF YEAST PECTOLYTIC ENZYMES TO AID PINEAPPLE JUICE EXTRACTION

A crude preparation of pectolytic enzyme was obtained by culturing Saccharomyces cerevisiae (ATCC512712) in pineapple juice. Maximum cell growth was obtained on the 6th day after inoculation. Correspondingly, optimum protein concentration and enzyme activity were also observed on the 6th day old culture. Although not purified, the addition of this crude enzyme extract to crushed pineapple mash at 0.02% resulted in a significant increase in juice yield (P≥0.05). The overall processing time was also significantly reduced (P≤0.05) with the enzyme treatment compared to controls. A combination of 0.02% enzyme treatment of mash for 30 min, was found to be the most effective dosage in reducing the processing time significantly.     

以胡萝卜为原料的添加赤藓糖醇功能性饮料的研制

以胡萝卜为原料,通过果胶酶水解胡萝卜中的多糖物质,使之分解为可溶性单糖或低聚糖等利于人体吸收的糖类,并添加功能性甜味剂-赤藓糖醇来研制功能性饮料.通过正交试验确定赤藓糖醇添加量为5%、原料液43%、热烫水30%、乳化剂用量0.8%;果胶酶用量在0.02%,最适pH为4.0,45℃酶解3 h时吸光值最低,经科学组方调配后,可获得该饮料最佳口感.     

Optimization of extraction process of crude polysaccharides from boat-fruited sterculia seeds by response surface methodology

Response surface methodology (RSM) was applied to optimize the extraction of crude polysaccharides from boat-fruited sterculia seeds. A central composite design was used for experimental design and analysis of the results to obtain the optimal extraction conditions. Extraction temperature, pH, extraction time and water to seed ratio were found to have a significant influence on the yield and purity of the extracted crude polysaccharides, while the three other factors except the water to seed ratio also significantly affected the relative viscosity. Based on the RSM analysis, optimum conditions were: temperature 60–65 °C, time 2.3–3.1 h, pH at 7.0 and water to seed ratio at 75:1. Under the optimized conditions, the experimental values were in close agreement with values predicted by the model. The crude polysaccharides prepared under optimum conditions contained 58.2% total carbohydrates (including uronic acids), 20% proteins, 9% moisture and 4.5% ash. The crude polysaccharides consisted of glucose (22.6%), rhamnose (10.0%), arabinose (7.9%), galactose (5.0%), xylose (0.8%) and galacturonic acid (11.8%).     

Characteristics of a novel bacterial polysaccharide consisted of glucose and mannose as major components

A bacterial strain, designated KMBL 5781, producing a high level of extracellular biopolymer was isolated from soil and identified as Mitsuaria chitosanitabida based on the 16S rRNA gene sequences. The biopolymer was purified by the sequential precipitation using ethanol, cethyl trimethyl ammonium bromide and then ethanol again. Its molecular weight was estimated to be about 54.7 kDa by the MALDI-TOF analysis. GC–MS analysis revealed that it is a polysaccharide consisting of glucose, mannose and galactose with approximate molar ratio of 18:6:1. In lower concentrations such as 0.5% and 1% viscosities of the EPS solution was higher than that of the xanthan gum used as a control. At the final range of shear rate the viscosity of 0.5% EPS was 34 cP while 0.5% xanthan showed 19.8 cP. The 1% EPS solution at the same rate has shown 59 cP and the viscosity of 1% Xanthan was 35 cP. When heated from 20 to 92 °C, the EPS solution (2%) remain stable from room temperature until 60 °C and showed significantly higher viscosity at 92 °C than 2% xanthan. The EPS hydrogel (2%) was strongly stable, which released no water during the incubation at 4 °C for 20 days and even after the tubes containing the gel was centrifuged at 4000× g for 10 min. Addition of the EPS into the starch solution resulted in the increase the weight and volume of the gel.     

Effect of high hydrostatic pressure and temperature on carrot peroxidase inactivation

The combined effects of pressure and temperature on the activity of carrot peroxidase (POD) were investigated in the pressure range 0.1–600 MPa and the temperature range 25–45 °C. At lower pressures (<396 MPa), carrot POD stability increased compared to unpressurized samples. Inactivation of 91% was obtained at 600 MPa and 45 °C. High hydrostatic pressure (HHP) combined with temperature treatment enhanced the inactivation of carrot POD. Regeneration of POD activity with the combined HHP and temperature treatments followed first order kinetics at 25, 35 and 40 °C. Regeneration was not observed at 506 MPa and 45 °C. HHP had no significant effect on the loss of vitamin C or on protein content. HHP combined with mild heat treatment was found to be better than the thermal treatment at high temperatures for inactivation of POD in carrot processing.     

Recovery of volatile fruit juice aroma compounds by membrane technology: Sweeping gas versus vacuum membrane distillation

The influence of temperature (10–45 °C), feed flow rate (300–500 L/h) and sweeping gas flow rate (1.2–2 m³/h) on the recovery of berry fruit juice aroma compounds by sweeping gas membrane distillation (SGMD) was examined on an aroma model solution and on black currant juice in a lab scale membrane distillation set up. The data were compared to recovery of the aroma compounds by vacuum membrane distillation (VMD). The flux of SGMD increased with an increase in temperature, feed flow rate or sweeping gas flow rate. Increased temperature and feed flow rate also increased the concentration factors (C_permeate/C_feed) of the aroma compounds. At 45 °C the most volatile and hydrophobic aroma compounds obtained the highest concentration factors: 12.1–9.3 (black currant juice) and 17.2–12.8 (model solution). With black currant juice a volume reduction of 13.7% (vol.%) at 45 °C, 400 L/h, resulted in an aroma recovery of 73–84 vol.% for the most volatile compounds. Compared to VMD, the aroma recovery with SGMD was less influenced by the feed flow rate but more influenced by the temperature. Higher fluxes were achieved during concentration by VMD and this reduced the operation time, which in turn reduced the degradation of anthocyanins and polyphenolic compounds in the juice.

Industrial relevance

High temperature evaporation is the most widely used industrial technique for aroma recovery and concentration of juices, but membrane distillation (MD) may provide for gentler aroma stripping and lower energy consumption. This study gives important clues about the fate of berry juice aroma compounds and polyphenols during concentration by MD, and identifies the main factors influencing the aroma recovery efficiency with MD. Both SGMD and VMD are promising techniques for gentle stripping of berry juice aroma compounds and deserve further consideration as alternative techniques for gentle aroma stripping in industrial fruit juice processing.     

Improved iron solubility in carrot juice fermented by homo- and hetero-fermentative lactic acid bacteria

To evaluate lactic acid fermentation as a means to increase the availability of iron in carrot juice, two strains (Lactobacillus pentosus FSC1 and Leuconostoc mesenteroides FSC2), two types of carrot juice and two modes of fermentation were compared. Fermentation improved iron solubility up to 30 fold. The total mineral content and the yield of soluble iron differed between the two types of juice. Addition of pectolytic enzyme and cellulase further improved iron solubility in fermented juice by about 10%. L. pentosus FSC1 yielded the largest improvement in soluble iron, which was not simply a result of a decrease in pH. The concentration of soluble iron in Ln. mesenteroides FSC2 fermentation was linearly related to the major acids produced. Besides, the mineral inhibitor phytate was completely degraded in all the fermentations.Lactic acid fermentation strongly improves iron solubility in carrot juice. The level of improvement was strain specific and related to the produced acids rather than a simple pH effect. Composition of carrot juice and addition of viscosity-reducing enzymes also contributed to this improvement. Our study suggests that carrot juice with high mineral availability may be achieved by fermentation using selected starter cultures, substrate and process.     

Development of a solid-state fermentation process for production of an alpha amylase with potentially interesting properties

Ca-independency with potential activity and stability at low pH are among the most interesting characteristics of α-amylase in starch industry. In this attempt the synergetic effect of low pH on activity of crude Ca-independent α-amylase isolated from a native Bacillus sp. KR-8104 in solid-state fermentation (SSF) was studied using wheat bran (WB) as a substrate. The effects of different parameters including moisturizing agents, solid substrate to moisture ratio, particle size, incubation temperature and period, inoculum (v/w) and supplementation with 1% (w/w) different carbon and nitrogen sources on enzyme production were investigated. Maximum enzyme production of 140 U/g dry fermented substrate was obtained from wheat bran moistened with tap water at a ratio of 1:1.5 and supplemented with 1% (w/w) NH₄NO₃ and 1% (w/w) lactose after 48 h incubation at 37 °C. Even though the production of α-amylase was lower at 40 and 45 °C, the viable cell count was higher. In addition response surface methodology (RSM) was applied to find optimum conditions of temperature and pH on crude amylase activity. Using central composite design (CCD) a quadratic mathematical model equation was derived for the prediction of enzyme activity. The results showed that the model was in good agreement with experimental results, with R² = 0.90 (p < 0.0001) and the low pH has a synergetic effect on enzyme activity at higher temperature.