Juice Parameters Research Articles

Physicochemical Characteristics of Orange Juice Samples From Seven Cultivars

Some physicochemical parameters of orange juice from seven orange varieties (Pineapple orange, Hamlin, Trovita, Jincheng, 1232 Tangor, Olinda Valencia, and Delta Valencia) were analyzed, special attention was paid to the level of sugars, organic acids, free amino acids, mineral composition, and color parameters. The results showed that total soluble solids (TSS), TSS/titratable acidity (TA) ratios, sugars, and organic acids were kept within a proper range for juice processing except that Jincheng had lower TSS than the others. Sucrose was the most dominant sugar in the orange cultivars, followed by fructose and glucose, while citric acid was the principal organic acid. Serine and proline were the principal amino acids. Potassium was the most abundant mineral in all of the juice samples, followed by magnesium and calcium. The sodium content of most varieties was under 10 mg kg −1. Though all of the samples had orange colour, Olinda Valencia and Delta Valencia had deeper red colour than the others. Statistically significant differences ( P<0.05) were found between the samples in most of the characteristics. The results provided important information on the physicochemical characteristics of the varieties and on how to make the best use of orange cultivars for different purposes, which is of significance for both technological research and processing practice.

VISCOSITY AND QUALITY OF TOMATO JUICE AS AFFECTED BY PROCESSING METHODS

ABSTRACT Quality and viscosity of tomato juice is strongly governed by mechanical and thermal abuse during processing. The effect of processing and storage duration on the viscosity and quality parameters of tomato juice was evaluated in the present work. Tomato juice was obtained by two different methods, normal method (NM) and variable method (VM), and was heated by both conventional and microwave hot break treatments. Tomato juice was evaluated for various quality characteristics including precipitate weight ratio, degree of serum separation (DOSS), Brookfield viscosity, lycopene levels, vitamin C, phenols and antioxidant activity. Changes observed in several quality parameters during storage were statistically insignificant. The methods and processing had the greatest contribution toward viscosity, whereas storage duration had no significant effects. Viscosity parameters viz precipitate weight, DOSS and Bostwick consistency revealed that juice processed by VM was more viscous than that of NM, irrespective of the hot break processing used. Ascorbic acid and lycopene content varied significantly with mechanical methods and processing conditions. However, phenolic content and antioxidant activity remained stable. The variable process represents an improvement over the conventional by enabling tomato processors to improve the consistency of the tomato product.PRACTICAL APPLICATIONSQuartering or slicing tomatoes followed by hot break processing techniques can significantly improve the quality of tomato juice in terms of reduced degree of serum separation and precipitate weight ratio. The modified technology could be considered as a viable and economical method for small‐ and medium‐scale tomato processors with limited resources and facilities at their disposal.

Evaluation of enzymatic treatment of peach juice using response surface methodology

AbstractBACKGROUND: This work aimed to assess peach juice clarification using enzymatic treatment. The enzymatic hydrolysis was performed to reduce the juice viscosity and pulp content, and consequently to increase juice extraction. The hydrolysis conditions were optimized by the response surface methodology, where the influence of temperature, amount and type of enzyme and time of reaction were investigated.RESULTS: Two commercial pectinase preparations (AFP L3 and ULTRA SP WOP from Novozymes) as well as a cellulase (R10 from Onozuka) were tested. The hydrolysis using Pectinex AFP L3 (Novozymes) at 25 °C for 60 min presented the best results of pulp (48%) and viscosity (68%) reduction.CONCLUSION: Physical and chemical analyses showed that the enzymatic treatment is effective for reduction of peach pulp viscosity, pulp content and turbidity and does not influence other juice parameters such as pH, total acidity, vitamin C and soluble solids. Copyright © 2007 Society of Chemical Industry

Investigation of the Mechanisms Underlying the Gastroprotective Effect of Nicorandil

Aim: This study investigated possible mechanisms underlying the gastroprotective effect of nicorandil on experimentally-induced gastric lesions in rats. Methods: Rats were randomly assigned to vehicle-, nicorandil (10 mg/kg)-, glibenclamide (6 mg/kg)-, nicorandil + glibenclamide- and cimetidine-pretreated groups, in addition to non-stressed control group, to demonstrate whether the K_ATPchannel opening contributed to nicorandil’s gastroprotection. Lesions were induced by water immersion-restraint stress (WIRS) and ulcer indices were determined. Gastric juice parameters (pH, acid output, pepsin and mucin concentrations) were determined. Another set of rats was divided into control, saline-pretreated and nicorandil (10 mg/kg)-pretreated groups. Rats underwent WIRS and their stomachs were used for determination of gastric mucosal lipid peroxides, histamine, PGE₂, and total nitrites levels. Results: Nicorandil displayed significant protection against gastric lesions formation, abolished by concomitant administration of glibenclamide. Nicorandil significantly reduced gastric acid and pepsin secretion, but upon coadministration with glibenclamide, these effects were blocked. Additionally, nicorandil significantly reduced gastric mucosal lipid peroxides and total nitrites, but did not affect PGE₂ and histamine levels. Conclusion: Results confirm a gastroprotective effect for nicorandil, the mechanism of which comprises K_ATP channel opening, free radical scavenging, decrease of pepsin and acid secretion and prevention of the detrimental rise in nitric oxide during WIRS.

Analytical characterization and the impact of ageing on anthocyanin composition and degradation in juices from five sour cherry cultivars

Five different sour cherry cultivars were processed to sour cherry juices in order to analyze their composition and the impact of storage on anthocyanin composition. Regarding primary juice parameters all cultivars showed high dry masses (13.8–17.2° Brix) and sugar free extracts (59.4–74.3 g/L). Anthocyanins were identified as cyanidin-3-(2G-glucosylrutinoside), cyanidin-3-(2G-xylosylrutinoside), cyanidin-3-sophoroside, cyanidin-3-glucoside, cyanidin-3-rutinoside, and peonidin-3-rutinoside. Besides the original anthocyanins, 5-carboxypyrano-anthocyanins occurred as new reaction products during storage. HPLC-MSn experiments revealed, that a further ageing pigment was probably resulting from the reaction of an original anthocyanin with acetaldehyde. A significant decline of the original anthocyanin concentrations could be observed (70–75%) during 6 months of storage at 20 °C. Degradation kinetics of anthocyanins were calculated taking the reaction rate as first order. Colourless polyphenol concentrations and antioxidant capacities (TEAC) of the juices were not affected during storage.

Antiulcerogenic activity of Alchornea castaneaefolia: Effects on somatostatin, gastrin and prostaglandin

The hydroethanolic extract of the leaves (HEL) and bark (HEB) obtained from Alchornea castaneaefolia (Euphorbiaceae) were investigated for their ability to prevent ulceration of the gastric mucosa in animal models. HEL (500 and 1000mg/kg) and HEB (1000mg/kg) significantly reduced the gastric injuries induced by the combination of HCl/ethanol and lowered the severity of gastric damage formation induced by indomethacin/bethanechol in mice. Further investigation showed that HEL also inhibited formation of ulcers in mice submitted to stress and pylorus ligature, but HEL did not modify gastric juice parameters in Shay mice. HEL was also effective in promoting the healing process in chronic gastric ulcer induced by acetic acid in rats. An enriched flavonoidic fraction (EFF at dose of 100mg/kg) obtained from HEL reduced gastric lesions induced by HCl/ethanol and indomethacin/bethanechol in mice. Although EFF did not modify the amount of free mucus production by gastric mucosa, it was able to increase prostaglandin production. When administered to rats submitted to ethanol-induced gastric lesions, EFF increased the somatostatin serum levels, while the gastrin serum levels were proportionally decreased. Phytochemical investigation on HEL and EFF led to the isolation of flavonoids glycosides as the main compounds, thus suggesting that these substances may be involved in the observed antiulcer activity.

Qualea grandiflora, a Brazilian “Cerrado” medicinal plant presents an important antiulcer activity

Qualea grandiflora is one of the species widely used in folk medicine to treat gastric ulcers in Cerrado of the central region of Brazil. The hydroalcoholic extract of bark (HE) of Qualea grandiflora was investigated for their ability to prevent and heal lesions in the gastric mucosa. The oral administration of HE exhibited antiulcer activity decreasing the ulcerative index induced by HCl/ethanol solution, indomethacin/bethanechol and stress. In the Shay model, results showed that HE (p.o.) only reduced the severity of gastric lesions without effects on pH, gastric acidity or volume. When given by intraduodenal route, HE changed the pH, but did not modify the other parameters of the gastric juice. These data were in accordance with those obtained when HE was administered orally for 14 days after gastric ulcers were induced by acetic acid in rats. HE presented healing process in subacute gastric ulcer induced by acetic acid in rats. Moreover, histological examinations showed the simple columnar epithelium, lamina propria with simple branched tubular glandules with dilated lumen and large amounts of mucus secretion. Phytochemical investigation of HE led to the detection of terpenes, steroids, saponins, phenolic compounds and tannins in this extract, which may be involved in the observed activity.

Comparative study on shelf life of orange juice processed by high intensity pulsed electric fields or heat treatment

The effects of high intensity pulsed electric fields (HIPEF) processing (35 kV/cm for 1,000 μs; bipolar 4-μs pulses at 200 Hz) on the microbial shelf life and quality-related parameters of orange juice were investigated during storage at 4 and 22 °C and compared to traditional heat pasteurization (90 °C for 1 min) and an unprocessed juice. HIPEF treatment ensured the microbiological stability of orange juice stored for 56 days under refrigeration but spoilage by naturally occurring microorganisms was detected within 30 days of storage at 22 °C. Pectin methyl esterase (PME) of HIPEF-treated orange juice was inactivated by 81.6% whereas heat pasteurization achieved a 100% inactivation. Peroxidase (POD) was destroyed more efficiently with HIPEF processing (100%) than with the thermal treatment (96%). HIPEF-treated orange juice retained better color than heat-pasteurized juice throughout storage but no differences (p<0.05) were found between treatments in pH, acidity and °Brix. Vitamin C retention was outstandingly higher in orange juice processed by HIPEF fitting recommended daily intake standards throughout 56 days storage at 4 °C, whereas heat-processed juice exhibited a poor vitamin C retention beyond 14 days storage (25.2–42.8%). The antioxidant capacity of both treated and untreated orange juice decreased slightly during storage. Heat treatments resulted in lower free-radical scavenging values but no differences (p<0.05) were found between HIPEF-processed and unprocessed orange juice.

Anthocyanin−Flavanol Condensation Products from Black Currant (Ribes nigrum L.)

Putative flavanol-anthocyanin condensation products were detected in a polyphenol-rich concentrate from black currant (Ribes nigrum L.). These compounds had UV-vis spectra similar to those of delphinidin-3-O-rutinoside and cyanidin-3-O-rutinoside, but eluted before all previously described anthocyanins on reversed phase HPLC. Mass spectrometric data indicated that they were rutinoside derivatives of novel aglycons 304 amu greater than delphinidin and cyanidin, respectively. The compounds were partly purified by semipreparative HPLC and gave MS and MS2 spectra consistent with anthocyanin rutinosides covalently linked to epigallocatechin or gallocatechin. These compounds are similar in structure to compounds thought to influence color and quality in red wines and strawberry juice products. There was also evidence for the presence of a range of other flavanol-anthocyanin condensation products. The compounds were present at differing levels in juices of 10 black currant varieties, which were roughly correlated to the content of the parent anthocyanins. The flavanol-anthocyanin products were present in polyphenol-enriched concentrates obtained by solid phase extraction, in commercially produced concentrates, and in fresh extracts of black currants. This suggests that the compounds were not artifacts formed during concentration or purification. However, differences in their comparative contents may be related to the lability of the parent anthocyanins during processing. Although present at low levels, the flavanol-anthocyanin products may influence color or quality parameters of black currant juices, and they may confer enhanced stability to the biological activities reported for their anthocyanin parents.

Gastroprotective activity of Pradosia huberi on experimentally induced gastric lesions in rodents: Role of endogenous sulphydryls and nitric oxide

Pradosia huberi is a medicinal plant very common in the Amazonian forest population. The research interest in this plant is justifiable because of its potential medicinal value in gastritis and gastric ulcer mentioned in local folk medicine. In this paper, we evaluated the acute toxicity and antiulcerogenic effect of a hydroalcoholic extract (HAE) obtained from Pradosia huberi barks in rodents. No acute toxicological sign or symptom was observed in animals treated with the highest dose (5000 mg/kg, p.o.) of Pradosia huberi. In the HCl/EtOH-induced gastric ulcer model, HAE demonstrated significant inhibition of the ulcerative lesion index by 73% (500 mg/kg) and 88% (1000 mg/kg), respectively, in relation to the control value ( p < 0.05). The gastric damage induced by absolute ethanol in rats was effectively reduced by 84, 88 and 81% (250, 500 and 1000 mg/kg) when compared with the control group ( p < 0.01). In the NSAID-induced lesion model, HAE also showed antiulcerogenic effect with decrease in gastric lesions of 56% (250 mg/kg), 57% (500 mg/kg) and 67 % (1000 mg/kg) when compared with animals treated with vehicle ( p < 0.05). In the gastric ulcer induced by pylorus ligature model, the administration of HAE by oral and intraduodenal routes inhibited the gastric lesion index by 79 and 52% (500 mg/kg), respectively. HAE administered orally or intraduodenally was able to change gastric juice parameters (pH, volume and acid output) as well as those treated with cimetidine. The treatment with HAE (p.o.) significantly increased gastric volume, the pH values and promoted reduced acid output ( p < 0.01). By comparative effect (intraduodenal and oral route), we observed that HAE was better for local activity in gastric mucosa than in systemic action. HAE also has a non-specific activity when found to be the inhibitor of intestinal motility ( p > 0.01). The mechanism of action of HAE did not seem to be related to the NO-inhibitor but showed the participation of endogenous sulphydryl group in the gastroprotective action.

Preliminary studies of Mammea americana L. (Guttiferae) bark/latex extract point to an effective antiulcer effect on gastric ulcer models in mice

Plant extracts are some of the most attractive sources of new drugs and have shown promising results for the treatment of gastric ulcers. Several folk medicinal plants and herbs have been used to treat gastrointestinal disorders, including gastric ulcers. Mammea americana L. (Guttiferae) fruit is very common in the diet of the population of northern South America. Our research interest in this plant arose because of its potential medicinal value as a tonic and against stomachache, as used in folk medicine. In this paper we evaluated three different extracts (ethanolic/EtOH, methanolic/MeOH and dichloromethane/DCM) obtained from M. americana L., for their ability to protect the gastric mucosa against injuries caused by necrotizing agents (0.3 M HCl/60% EtOH), hypothermic restraint stress, nonsteroidal anti-inflammatory drugs (NSAID, indomethacin) and pylorus ligation. In the HCl/EtOH-induced gastric-ulcer model, EtOH and DCM extracts demonstrated significant inhibition of the ulcerative lesion index by 54% (12.0 +/- 2.6 mm) and 86% (3.7 +/- 1.8 mm), respectively, in relation to the control value (26.0 +/- 1.4 mm) (p<0.0001). In the NSAID/cholinomimetic-induced lesion model, both EtOH and DCM extracts showed antiulcerogenic effects with significant reduction in the damage to these gastric lesions of 36% (8.3 +/- 2.0 mm) and 42% (7.5 +/- 1.4 mm), respectively, as compared to the control group (13.0 +/- 0.9 mm) (p<0.0001). In the gastric ulcer induced by hypothermic-restraint stress, both extracts also showed significant activity, and inhibited the gastric lesion index by 58% and 75%, respectively. The EtOH and DCM extracts also changed gastric juice parameters as well as those of cimetidine, decreased gastric acid secretion significantly (p<0.0001), increased pH values and promoted reduced acid output (p<0.0001). In all gastric-ulcer-induced models, MeOH extract did not show any significant antiulcerogenic activity, nor did it change gastric-juice parameters (p>0.05). The results suggest that EtOH and DCM extracts obtained from M. americana possess excellent antisecretory and/or gastrotective effect in all gastric ulcer models. These results suggest that the antiulcerogenic compound(s) present in M. americana may be clustered in the apolar fraction, which will be investigated by our group for the probable mechanisms of action.

Evaluation of sugarcane varieties for maturity earliness and selection for efficient sugar accumulation

Aiming at producing adequate sugar yield, the initial selection from 26 varieties of sugarcane (Saccharum hybrids) was made over 14 months of growth on the bases of interrelated juice and sugar parameters including earliness age, high Pol % cane, purity and CCS. Selection standards of 15 Pol % cane, 85 % purity and 14.2 % CCS at maturity allowed the selection of 12 superior varieties including Q77N1232, Q136, Q127, BT65152, Cassius, Cadmus; PS57, PS58, Co6519, C06806, Co997 and Ragnar. Their maturity profiles showed that juice and cane parameters are significantly correlated. The first three varieties, Co 6806, Cadmus and Co 997, matured at <11 months (early maturing), and the remaining nine varieties; PS58, Co6519, BT65152, Q77N1232, Q136, Ragnar, Cassius, Q127 and PS57, matured at ≥11- 12 months (medium maturing). The 12 selected varieties were subjected to further selection based on a selection standard of 17.5 TSH, resulting in selecting eight top-most varieties; Q77N1232, Q127, BT65152, Cassius, Cadmus, Co6519, Co997 and Ragnar. Furthermore, selection based on moderate fibre content set at 14 ≥ fibre % cane allowed for the selection of four best varieties, (Q127, Cadmus, Co6519 and Ragnar). Ragnar, as an ideal variety with high sugar yield, tolerant to drought with medium maturity age and long production period, was taken as a standard, against which the other three varieties possessed higher values of juice parameters, with L14 the highest of all. However, L 14 was sensitive to drought, while the other two varieties were moderate. The superiority of L 14 is hindered by its sensitivity to drought. The overlapping of maturity age and prolonged production periods would prolong the harvesting season and make the cropping season more efficient, as it allows for early harvest, maintaining varietal diversification and sustainable production. The results provide significant information for the possible extension of sugarcane commercial cultivation in Papua New Guinea.

Antiulcerogenic activity of ethanol extract of Solanum variabile (false “jurubeba”)

The ethanol extract (EE) of the aerial parts of Solanum variabile Mart. (Solanaceae) was investigated for its ability to prevent ulceration of the gastric and duodenal mucosa at different doses. Its ability to heal chronic ulcer processes was also evaluated. When the HCl/ethanol solution was used to induce gastric ulcer, the EE produced a significant dose-dependent reduction of lesion formation of 51, 74 and 89%, at doses of 250, 500 and 1000 mg/kg, respectively. The 100 mg/kg dose had no significant activity. The EE also significantly reduced the gastric lesions induced by the combination of indomethacin and bethanechol (60 and 72%) at doses of 500 and 1000 mg/kg and also reduced stress-induced gastric ulcer (41%) but only at the doses of 1000 mg/g ( P<0.05). The pylorus-ligature experiment demonstrated that the highest EE dose affected significantly the gastric juice parameters by increasing pH values from 4.08 (negative control) to 5.42 and decreasing acid output from 7.16 (negative control) to 4.26 mEq. mL, 4 h. A decrease of gastric contents from 370 mg (negative control) to 240 mg was also observed. The results obtained in the chronic gastric ulcer model indicated that a single oral dose of Solanum variabile (1000 mg/kg) administered for 14 consecutive days accelerated the ulcer healing by 46% compared to a 55% effect of cimetidine. Also, at the dose of 1000 mg/kg, the EE inhibited the onset of duodenal lesions by 64%. The data suggest that the EE of Solanum variabile has a significant preventive, curative and duodenal anti-ulcer effect.

Fatty acid content and juice characteristics in black currant (Ribes nigrum L.) genotypes.

The fatty acid compositions of seeds from 29 black currant genotypes were determined using a rapid small-scale procedure. There was interest in alpha-linolenic, stearidonic, and, especially, gamma-linolenic acid (GLA) contents, and most samples showed values between 11.1 and 18.7%, between 2.5 and 4.5%, and between 11.6 and 17.4%, respectively. However, six genotypes exhibited gamma-linolenic contents >18%, and values >20% were recorded in four of these genotypes. The fatty acid contents of the six genotypes were also analyzed by using a conventional procedure, and only slight differences in fatty acid composition were found between the two methods. Although GLA content was not strongly correlated with juice parameters, some genotypes had both high GLA contents and desirable juice characteristics. The results obtained provide evidence that it is possible to select for GLA contents without negatively affecting juice quality, and both aspects can be combined in a single cultivar, thereby increasing the added value of the whole fruit.

Production of concentrated kiwifruit juice by integrated membrane process

The concentration of fruit juices is industrially performed in order to reduce storage, packaging, handling and shipping costs. This paper describes the research efforts to develop and optimise an integrated membrane process, on laboratory scale, for the production of concentrated kiwifruit juice as alternative to the traditional vacuum evaporation. Fresh depectinated kiwifruit juice was previously clarified by ultrafiltration (UF) process. In experimental tests performed according to the total recycle mode the effect of transmembrane pressure, axial flow-rate and temperature on permeate fluxes were studied. Clarified kiwifruit juice was produced in experimental tests carried out according to the batch concentration mode working in optimal operating and fluid dynamic conditions. The osmotic distillation (OD) process was used to concentrate the clarified juice up to a total soluble solids (TSS) content higher than 60 °Brix at 25 °C. The effect of various operating parameters on vapour flux was studied. An average evaporation flux of almost 1 kg/m 2 h was obtained using a calcium chloride dihydrate at 60 w/w% as brine solution. The effects of UF and OD processes on the total antioxidant activity (TAA) and other analytical parameters of the kiwifruit juice were also studied. A little reduction of the TAA was measured during the membrane treatment; vitamin C content was well preserved in the concentrated juice. On the basis of the results obtained on laboratory scale an integrated membrane process scheme for the clarification and the concentration of kiwifruit juice is proposed.

Antiulcerogenic effect and cytotoxic activity of semi-synthetic crotonin obtained from Croton cajucara Benth.

Trans-dehydrocrotonin, the major diterpene isolated from the bark of Croton cajucara, has good antiulcerogenic activity which, however, is accompanied by toxic effects. On the basis of these results, a semi-synthetic crotonin, named 4SRC, was prepared to determine whether this substance has similar antiulcerogenic activity with lower or no toxicity. The natural crotonin was also isolated from the bark of C. cajucara but was not used due to the small amount obtained. The cytotoxic effect of semi-synthetic crotonin, expressed as cell viability, was assessed in (a) lung fibroblast cell line (V79) derived from Chinese hamsters, a system commonly used for cytotoxicity studies, and (b) rat hepatocytes isolated from male Wistar rats. After treatment, cell viability was determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide reduction (MTT reduction), total acid content and neutral red uptake assays. To evaluate V79 cell viability, different concentrations of semi-synthetic crotonin were incubated with the cells. To evaluate the antiulcerogenic effects of semi-synthetic crotonin (50, 100 and 200 mg/kg), we used the models of gastric ulcer induced by ethanol/HCl, stress, indomethacin/bethanechol, and ethanol in male Swiss mice and male Wistar rats. The substance had an IC 50=500 μM in the neutral red uptake and MTT reduction tests and an IC 50=200 μM in the nucleic acid content test. With regard to hepatocyte viability after treatment with semi-synthetic crotonin at different concentrations, semi-synthetic crotonin had an IC 50=10–500 μM in the nucleic acid content and MTT reduction tests and an IC 50=120 μM in the neutral red uptake test. In another experiment, V79 cells were incubated with the metabolites produced by hepatocytes treated with different concentrations of semi-synthetic crotonin. After a 4-h incubation, semi-synthetic crotonin had an IC 50=500 μM in the MTT reduction and neutral red uptake tests and an IC 50=370 μM in nucleic acid content test. The substance had significant antiulcerogenic activity in all models studied, suggesting the presence of a possible antisecretory effect combined with a cytoprotective effect. For this reason, the effect of semi-synthetic crotonin was also evaluated on biochemical parameters of gastric juice and gastric wall mucus, both obtained from pylorus-ligated mice. No significant differences were observed in these parameters between semi-synthetic crotonin-treated and control animals. The results obtained with semi-synthetic crotonin are promising, with a significant preventive effect against gastric ulcer induced by different agents. Our data also show that semi-synthetic crotonin was less toxic than dehydrocrotonin and that the cytotoxic effects decreases with the time that isolated hepatocytes were in culture.

The influence of enzymatic treatment of mash on the analytical composition of apple juice

Five apple juices were produced on a pilot scale by crushing the fruit, treating the mash with pectolytic enzymes, pressing, extracting water from the pomace, pasteurization, treatment of the juice with enzymes, combined gelatin/silica sol fining and final ultrafiltration. The temperature of the mash treatment was either ambient or one of 30, 40, 50 or 60 °C, in order to test whether this led to different compositional changes in the corresponding juices. The main emphasis was put on detection of D‐galacturonic acid as the indicator substance for the extent of the enzymatic treatment. In the pasteurized raw juices after pressing we found values from 226 to 398 mg L−1. A distinct increase of the galacturonic acid levels could be observed during the clarification steps. Enzymatic juice treatment raised the concentrations to 580–720 mg L−1. After ultrafiltration, final values of 790–1100 mg L−1 were measured. Generally, the highest values were found in the 50 °C sample, which is the optimum temperature for pectinase activity. This was also true for the colloid concentrations and polyphenols. The influence of the temperature of the enzymatic mash treatment on other characteristic juice parameters like total titratable acidity, density, sugar, and minerals concentrations was low.

Effect of concentration and drying processes on color change of grape juice and leather (pestil)

The Hunter color parameters (L,a,b) of grape juice during boiling, cooking and of pestil samples (1.53 mm) during drying were investigated. It was found that most of the color changes occurred during grape juice boiling. However, during hot air or sun drying only the Hunter a-value changed. The reaction associated with color change followed zero-order reaction kinetics. The temperature dependence of the reaction rate constant was described by an Arrhenius-type equation.

Antiulcerogenic activity of four extracts obtained from the bark wood of Quassia amara L. (Simaroubaceae).

Quassia amara L., a neotropical forest shrub of the Simaroubaceae family, is widely used in Caribbean folk medicine and in some northern states of Brazil for the treatment of gastric ulcers. This plant is a source of numerous compounds including both beta-carbonile and cantin-6 alkaloids as well as, primarily, the bitter compounds known as quassinoids. We analyzed the possible antiulcerogenic activities of four extracts of different polarities: 70% ethanol (70% EtOH), 100% EtOH, 100% dichloromethane (DCM), and 100% hexane (HEX) obtained from Quassia amara bark. All extracts, administered at doses of 5000 mg/kg orally and 1000 mg/kg intraperitoneally, caused neither toxicity or death. In the indomethacin/bethanechol-induced gastric ulcer, 70% EtOH, 100% EtOH, DCM and HEX extracts, 100 mg/kg, p.o., inhibited the gastric ulcer (22.5, 23.4, 50.5, 46.8%, respectively). 70% EtOH, 100% EtOH, DCM, and HEX extracts reduced the gastric injury induced by the hypothermic restraint-stress test in mice (70.7, 80, 60, 82.7%, respectively). In the pylorus ligature of the mouse stomach, following pre-treatment with a single intraduodenal administration of 100 mg/kg of each extract, only 70% EtOH did not change the biochemical parameters of gastric juice. 100% EtOH, DCM and HEX extracts presented decreased gastric juice content, increased pH values and decreased acid output. We also determined the antiulcerogenic activity on HCl-EtOH-induced gastric ulcers in mice at four doses (25, 50, 75, 100 mg/kg, p.o.), then evaluated the possible dose-dependent relation and calculated the ED50 values. Except for 70% EtOH at a dose of 25 mg/kg, the other extracts showed significantly activity (p<0.05). The free mucous amount in the gastric stomach content was also evaluated. All extracts showed significant increases (p<0.05) of free mucous. This effect was abolished when the animals were pre-treated with indomethacin. Prostaglandin synthesis was evaluated by the administration of HEX extracts by the oral route (100 mg/kg). Prostaglandin synthesis was significantly, increased by 52.3% (p<0.05), and this effect was abolished with prior administration of indomethacin. We concluded that Quassia amara is a probable source for a new drug to treat gastric ulcers, and the mechanism of its activity relates to cytoprotective factors, such as mucous and prostaglandins, but there is still the possibility that antisecretory activity is involved in its antiulcerogenic effect.

Effects of High-Pressure Treatment on the Sensory Quality of White Grape Juice

The effects of high-pressure treatment on the colour (objective measurement) and sensory characteristics of white grape juice were studied during storage at 4 °C for 60 days. Grape juice was subjected to three different treatments: 400 or 500 MPa at 2 u °C, and 400 MPa at 40 °C during 10 min. Untreated juice was used as control. Colour parameters (CIE L * a * b *), hue angle (tan m 1 b */ a *), chroma {( a * 2 + b * 2 ) 1/2 }, luminosity Q *{(10 2 log( L *) + 100} and saturation S *( C */ L *) were measured. Juices were evaluated for sweetness, acidity, off-flavour and aroma. High-pressure treatments did not affect the colour parameters of juice, and similar sensory characteristics were observed in both control and treated samples on the first day. The colour and sensory characteristics of pressure-treated samples remained more stable than those of the control juice during 60 days of storage. The control juice was slightly fermented developing some changes in flavour and colour.