Juice Solids Research Articles

Nondestructive Determination of Sweetness of Orange Juice using Portable Near Infrared Spectroscopy

A simple and nondestructive method using portable near infrared spectroscopy (NIRS) was investigated to determine the total soluble solids (TSS) of orange juice. Juice from I 10 orange was squeezed and tqeir spectra in the range of 311.7 - 1124.8 nm wavelength were acquired using a portable Vis-NIR spectrometer and fibre optics as light transmitting medium. Sweetness in terms of total soluble solids contents of juice was determined using a digital refractometer. Whole samples were divided into two sets: calibration and validation; and partial least squares regression of spectral data in wavelength region from 703.3 to 1124.8 nm was performed. The standard errors of calibration and validation were found to be 0.47° and 0.4 FBrix, respectively, which are reasonably low. It indicates that sweetness of juice may be determined non-destructively using a portable NIR spectrometer without sacrificing accuracy as compared to that by a refractometer.

Optimization of an Enzyme Assisted Process for Juice Extraction and Clarification from Litchis (Litchi Chinensis Sonn.)

Litchi pulp was treated with various concentration levels of hydrolytic enzymes viz. pectinase (0-0.133%w/w), cellulase (0-0.266%w/w) and hemicellulase (0-0.20%w/w) for different durations (30-150 min) at 45°C. The effect of enzyme treatment conditions was studied on yield, clarity, apparent viscosity and total soluble solids (TSS) of juice obtained from the pulp. The optimum process conditions were determined by employing a second order central composite rotatable design in combination with response surface methodology. Yield, clarity and TSS of juice were found to increase and apparent viscosity was found to decrease significantly by enzymatic treatment. The optimum conditions for enzymatic treatment of pulp obtained after a 2 sided desirability function with the responses juice yield, clarity and TSS to be maximized and viscosity to be minimized were 0.076% (w/w) pectinase, 0.138% (w/w) cellulase, 0.107% (w/w) hemicellulase and incubation time of 106.5 min. The predicted values for juice yield, clarity, viscosity and TSS under optimized conditions were 77.19 %, 93.53%, 1.359mPa s and 19.68°brix which showed a good agreement with the experimental values under the same set of conditions.

Optimization of an Enzyme Assisted Process for Juice Extraction and Clarification from Litchis (Litchi Chinensis Sonn.)

Litchi pulp was treated with various concentration levels of hydrolytic enzymes viz. pectinase (0-0.133%w/w), cellulase (0-0.266%w/w) and hemicellulase (0-0.20%w/w) for different durations (30-150 min) at 45°C. The effect of enzyme treatment conditions was studied on yield, clarity, apparent viscosity and total soluble solids (TSS) of juice obtained from the pulp. The optimum process conditions were determined by employing a second order central composite rotatable design in combination with response surface methodology. Yield, clarity and TSS of juice were found to increase and apparent viscosity was found to decrease significantly by enzymatic treatment. The optimum conditions for enzymatic treatment of pulp obtained after a 2 sided desirability function with the responses juice yield, clarity and TSS to be maximized and viscosity to be minimized were 0.076% (w/w) pectinase, 0.138% (w/w) cellulase, 0.107% (w/w) hemicellulase and incubation time of 106.5 min. The predicted values for juice yield, clarity, viscosity and TSS under optimized conditions were 77.19%, 93.53%, 1.359mPa s and 19.68°brix which showed a good agreement with the experimental values under same set of conditions.

Spray Drying of Raisin Juice Concentrate

Raisin juice concentrate is a natural sweetener in syrup or paste form and it is produced from second-grade dry raisins by leaching them with water. Dried raisin juice, although is easier to handle and has more potential applications than the syrup, is not available in the market. In the present study, raisin juice powder was produced with a lab-scale spray dryer. The problem of stickiness in the drying chamber was overcome through the use of 21 DE, 12 DE, and 6 DE maltodextrins as drying aid agents. For each type of maltodextrin, the dryer operating conditions and the minimum concentration of maltodextrin in the feed, necessary for successful powder production, were determined. The maximum ratio of (raisin juice solids)/(maltodextrin solids) achieved was 67/33 and was made possible with the use of 6 DE maltodextrin. The inlet and outlet drying air temperatures were 110 and 77°C respectively, while the feed contained 40% w/w total solids. The physical and sensory properties of all powders produced were determined and found to be satisfactory, the only exception being their high hygroscopicity.

Effects of Pruning and Cluster Thinning on Yield and Fruit Composition of `Chambourcin' Grapevines

Response of yield components and fruit composition of `Chambourcin' (Vitis vinifera × V. rupestris) grapevines to three pruning levels of 15, 20, and 25 nodes retained for each pound of dormant prunings; and three cluster thinning levels of 1, 2, and 2+ clusters per shoot in 2002 and 1, 1.2, and 1.5 clusters per shoot in 2003 were measured at two vineyards in the lower midwestern United States. In both years of the study, there was very little interaction of pruning and cluster thinning. The proportion of non-count shoots increased within the canopy in response to increased pruning severity. Pruning weight means were lower in 2002 across all treatments compared to 2003. Pruning weights decreased with the increase in the number of clusters retained per vine. Pruning influenced yield only in 2003 when the proportion of count shoots decreased below 62% of the total, hence the relationship between number of shoots per vine and yield (R2 = 0.3452; P < 0.0003). In both years of the study, the increase in severity of cluster thinning resulted in yield reduction but an increase in the total soluble solids in juice. Yield compensation was achieved by an increase in cluster weight of 38%, and 25% in response to a reduction of 37%, and 23% in cluster numbers; which translated into a yield reduction of only 10% and 3%, at Vineyards 1 and 2, respectively. Balanced pruning to 15 to 20 nodes per 1 lb of prunings and cluster thinning to 1 to 1.2 clusters/shoot optimized yield (9.7 kg/vine, 13.4 t·ha-1) and fruit composition, and maintained vine size (≥0.3 kg·m-1 of row). These results provide valuable information for growers of `Chambourcin' grapevines in the lower midwestern U.S., as well as in other climates with long growing seasons.

ウンシュウミカンにおける果汁の糖度と次年度生産性との関係

ウンシュウミカン‘宮川早生’，‘繁田温州’，‘青島温州’において，着果負担を表すものと想定される生産性項目（着花程度，結実数，収穫果数，収量）および果実重，果汁の糖度と次年度の生産性項目（着花程度，結実数，収量）との間の関係について，特に果汁の糖度に着目して解析した．‘宮川早生’では生産性項目の変動が小さく，明確な関係はみられなかった．‘繁田温州’と‘青島温州’では，次年度の 生産性項目に対して，生産性項目は負の相関が，果実重および糖度は正の相関が認められた．重回帰分析により，次年度の生産性は主として着果負担の軽重に左右されるが，補足要因として糖度が有効であり，高い重相関係数が認められた．相関図より，次年度の着花程度は糖度が高くなるほど高く，結実数や収量も糖度12度程度までは増加すること，ただし，‘青島温州’において糖度が12度を超えて高まる樹では次年度の結実数や収量は減少する傾向であることが示された．以上より，‘繁田温州’と‘青島温州’では糖度は次年度の生産性を予測する指標として有効であり，収穫時の糖度12度程度までの高品質化は安定生産と両立することが推察された．

HORTICULTURAL CHARACTERISTICS OF MAYHAW (Crataegus opaca) CLONES FROM A 36-YEAR-OLD NATIVE POPULATION

National demand for authentic Southern cuisine has contributed to the increased utilization of mayhaw fruit. Certain fruit characteristics are essential for the processing of mayhaw. Most of the mayhaw fruit used in processing comes from wild populations. Efforts are being made to identify superior clones from native populations. This study was undertaken to determine the chances of finding a superior clone with desirable processing attributes in a completely random population of mayhaw seedlings. Trees were removed from a 36 year-old mayhaw seedling orchard and relocated to a new orchard. The original orchard contained over 1500 trees. Five years after establishment in the new orchard, fruit were harvested from 75 of the trees and evaluated for fruit weight, percent malic acid, percent soluble solids, and color. Of the 75 trees, 48 were within one standard deviation of the mean trunk diameter. Seven trees fell below 12.1 cm and only 4 trees were larger than 19 cm. The mean fruit weight was 2.1 g with a range from 1.77-2.4 g. Sixty-seven percent of the trees produced fruit having weights within one standard deviation of the mean. Percent malic acid of mayhaw juice averaged 1.35% among the 75 trees. Seventy-two percent of the trees produced fruit with percent malic acid within one standard deviation of the mean. Mean percent soluble solids of mayhaw juice were 6.1 with a range of 5.36% to 7.01%. Seventy-three percent of the trees produced fruit with soluble solids percentages within one standard deviation of the mean. The probability of finding individuals in this population that exceeded the mean of these parameters (percent malic acid,%SS, and fruit weight) is less than 10%.

Effect of Encapsulating Materials on Water Sorption, Glass Transition and Stability of Juice From Immature Acerola

Immature acerola juice was dehydrated by spray drying, using as encapsulating material maltodextrin DE25, arabic gum, or a mixture of both in different proportions. A constant ratio of 1:1 was kept between juice solids and encapsulating material. The effect of encapsulation materials on water sorption, glass transition, and physical properties of encapsulated immature acerola juice was investigated. The monolayer moisture of the encapsulated juices, calculated according to the GAB theory, varied from 5.11 to 5.73g H2O/100g of solids (25°C). The glass transition temperature (Tg) of maltodextrin and gum arabic varied from 60 (aw 0.33) to 38°C (aw 0.54), and from 62 (aw 0.33) to 42.6°C (aw 0.54), respectively. The addition of juice to the encapsulating materials decreased the Tg of the juice powder to 39.5–41.3°C (aw 0.33) and 1.84–8.05°C (aw 0.54), but no marked differences were found among the juice powders. The critical aw, i.e., the point of onset of physical alterations in the encapsulated materials, was higher than the corresponding monolayer values. Stickiness was observed at temperatures close to Tg, and collapse occurred at temperatures of 20°C or more above the Tg. Maltodextrin DE25 and gum arabic offered equivalent contributions to the stability of the system.

Source - sink manipulation to increase melon (Cucumis melo L.) fruit biomass and soluble sugar content

Various source–sink perturbations were employed to alter partitioning to orange flesh melon (Cucumis melo L. reticulatus group) and thus to influence fruit biomass and soluble sugar content (indexed as total soluble solids of fruit juice, % TSS), with attention given to the timing of treatment application. A strong relationship existed between harvest index and fruit mass (r2 = 0.88) in control plants, whereas the correlation with fruit TSS was poor (r2 = 0.11). Augmentation of assimilate supply to fruit early in fruit development (before approx. 21 days before harvest, DBH) resulted in more fruit set and increased fruit biomass, whereas augmentation after 21 DBH resulted in increased fruit TSS. Thus, fruit biomass was increased (1644 cf. 1442 g FW per fruit for control, P = 0.02), but not TSS, on plants in which fruit set was delayed (source biomass increased, harvest index decreased from 59% for control to 38%). Treatment of plants with a cytokinin-based vegetative growth inhibitor at 14 DBH produced fruit with higher TSS (11.3 cf. 10.7% for control). Thinning fruit to leave 1 fruit per plant 1 week before harvest increased the proportion of fruit in a population that exceeded a quality control standard of 10% TSS from 20 to 80%. Variations in plant response with timing of treatment application are interpreted in terms of fruit development (cell division, cell expansion, and sugar accumulation phases). Although a detriment to yield (15 cf. 31 t/ha for control), the fruit thinning treatment was recommended for commercial use and a simple model was developed to calculate the required farm-gate price of fruit to make thinning economically viable.

Bacterial Contamination of Recirculating Brine Used in the Commercial Production of Moisture-Enhanced Pork

In a commercial process for the production of moisture-enhanced pork, boneless pork loins were conveyed through a recirculating injection apparatus, and brine (sodium phosphate, sodium chloride, and lemon juice solids) was pumped into the meat through banks of needles inserted automatically into the upper surfaces of cuts. Brine samples were collected at intervals during the production process and analyzed to determine the total plate count and the numbers of lactic acid bacteria, pseudomonads, Brochothrix thermosphacta, and Enterobacteriaceae. Listeria monocytogenes numbers in the brine were determined using a PCR with primers for the hemolysin gene in combination with a most probable numbers determination. Maximum numbers of bacteria (log CFU/ml) recovered from the brine after 2.5 h of recirculation were as follows: total plate count, 4.50; lactic acid bacteria, 2.99; pseudomonads, 3.95; B. thermosphacta, 2.79; and enterics, 3.01. There was an increase in the number of L. monocytogenes in the recirculating brine with time, reaching a maximum of 2.34 log CFU/100 ml after 2.5 h of moisture-enhanced pork production. Thus, recirculating brines can harbor large populations of spoilage bacteria and L. monocytogenes and are an important source of contamination for moisture-enhanced pork.

Processing effects on the composition of sea buckthorn juice from Hippophae rhamnoides L. Cv. Indian Summer.

Sea buckthorn juice is one product that can be derived from the sea buckthorn berry, a new alternative crop for the Canadian western provinces. Fresh pressed juice separates into three phases when allowed to stand overnight in the refrigerator: an upper cream phase, juice in the middle portion, and a sediment at the bottom. Enzymatic hydrolysis with commercial, broad spectrum carbohydrate hydrolyzing enzyme preparations reduced the juice viscosity, assisted juice separation, and provided an opalescent juice. Soluble solids averaged 10.2 degrees Brix, pH averaged 3.13, ascorbic acid averaged 174.2 mg/100 mL, and titratable acidity averaged 1.97% as malic acid all determined on centrifuged (10 000 rpm, 15 min) juice. Soluble sugars included glucose, fructose, and an unidentified component that was not sucrose or other common soluble monomeric or dimeric sugar. Quinic acid was quantitatively most important, while malic was next, and oxalic, citric, and tartaric acids were minor components. Washing berries by dipping reduced soluble solids (degrees Brix) in juice suggesting uptake of wash water.

Irradiation Inactivation of Four Salmonella Serotypes in Orange Juices with Various Turbidities

Reconstituted orange juice inoculated with Salmonella Anatum, Salmonella Infantis, Salmonella Newport, or Salmonella Stanley was treated with gamma radiation at 2°C. To determine the relationship between juice antioxidant power and Dγ (dose required to achieve 90% mortality), juice solids were removed prior to inoculation by centrifugation and/or filtration to create juice preparations of varying turbidity. In unadulterated orange juice, Salmonella Anatum (Dγ = 0.71 kGy) was significantly more resistant than the other species tested. Salmonella Newport (Dγ = 0.48 kGy) and Salmonella Infantis (Dγ = 0.35 kGy) were significantly different, while Salmonella Stanley (Dγ = 0.38 kGy) was intermediate between the two. Neither the resistance of each isolate nor the pattern of relative resistance among isolates was altered in reduced turbidity juice preparations. Although total antioxidant power was associated with the level of juice solids resuspended in phosphate buffer, antioxidant power was not significantly associated with turbidity in the juice preparations or with Dγ of any species. The variable resistance to irradiation of the Salmonella isolates suggests this as a more significant factor than turbidity or antioxidant power in designing antimicrobial juice irradiation protocols.

474 High Application Rates of Reclaimed Water Benefit Citrus Growth and Production

Citrus trees in an experimental planting responded well to high application rates of reclaimed water. Irrigation treatments included annual applications of 400 mm of well water and 400, 1250, and 2500 mm of reclaimed water. The effects of these irrigation treatments on two citrus cultivars (`Hamlin' orange and `Orlando' tangelo) combined with four rootstocks were compared. Growth and fruit production were better at the higher irrigation rates. The concentration of soluble solids in juice was diluted at the highest irrigation rate, but total soluble solids per hectare increased due to the greater fruit production. Average soluble solids/ha production was >15% higher at the 2500-mm rate than the 400-mm reclaimed water rate. While fruit soluble solids were usually lowered by higher irrigation, the reduction in fruit soluble solids observed on three of the rootstocks did not occur in trees on Carrizo citrange. Trees on Cleopatra mandarin grew similarly at the different irrigation rates, but canopy volume of trees on Swingle citrumelo was significantly smaller at the 400 mm rate than at the 2500 mm rate. Fruit peel color score was lower but juice color score was higher at the highest irrigation rate. Weed pressure increased with increasing irrigation rate, but was controllable. Both juice and fruit soluble solids were higher on Swingle citrumelo and lower on Cleopatra mandarin rootstock. Total soluble solids/ha, solids/acid ratio, and juice color were higher on Swingle rootstock. Reclaimed water, once believed to be a disposal problem in Florida, can be an acceptable source of irrigation water for citrus on well drained soils at rates up to twice the annual rainfall.

Soil salinity and sugarcane juice quality

Sugarcane ( Saccharum spp. hybrids) juice quality is reduced by soil salinity. If the effect of salinity in commercial production is predictable, it will be possible to estimate juice quality in salt-affected fields prior to harvest. Variation in the effects of soil salinity on sugarcane juice quality in commercial production was assessed using 15-stalk samples harvested in 1992 and 1993 from a salt-affected commercial field of CP 70-321 sugarcane. Mean electrical conductivity (EC e) of saturated water extracts of 54 (1992) or 74 (1993) soil cores from 0–30, 30–60, and 60–90 cm depths were used to calculate mean EC e at each site, which ranged from 0.5–17.0 dS m −1. Most of the increase in EC e was due to increases in Na + and Cl −. Magnesium, Ca 2+ and K + were also present. Stalk samples were harvested from 29 (1992) or 30 (1993) sites, with EC e ranging from 0.5 to 9.5 dS m −1. Each dS m −1 increase in EC e decreased Brix (% soluble solids in juice) and Pol (% sucrose in juice) by about 0.6%, decreased apparent purity (Pol as % of Brix) by 1.3% in 1993, increased juice conductivity 0.8 dS m −1, and increased cane residue (fiber) 0.5%. Effects of EC e on Brix, Pol and conductivity were very similar between years, indicating that the response of juice quality to salinity is predictable. This should allow development of sugar quality maps of commercial sugarcane fields for site-specific management decisions. Recoverable sugar yield per ton cane and per hectare were reduced by EC e in both years. In 1992, juice osmolality was less at the higher EC e sites, but in 1993 it was unaffected by EC e. About 90% of the osmolality of the juice was accounted for by the solutes analyzed (total sugar, Na +, K +, Ca 2+, Mg 2+, and Cl −). Potassium was the most abundant cation in the sugarcane juice (52.5 to 107 mmol c l −1). In 1992 there was a weak curvilinear ( R 2 = 0.35) increase in juice K + as EC e increased, while in 1993 K + tended to increase linearly with EC e ( r 2 = 0.20). Juice Na + increased with EC e from 4.9 to 37.4 mmol c l −1. There were also increases in juice Mg + (11.3 to 42.0 mmol c l −1) and Ca 2+ (2.2 to 22.4 mmol c l −1), with increased EC e. Most of the increase in juice conductivity was due to increases in Cl − (30.8 to 106 mmol c l −1). For most attributes there were no significant differences between years. This study shows in greater detail than most previous studies how soil salinity affects juice ionic composition, osmolality, and the accepted industry measurements of juice quality, Brix, Pol, apparent purity, and conductivity.

Juice extraction from apples and other fruits and vegetables

Presses are the usual and traditional method of removing juice from fruit and vegetable materials. However, recently diffusion extraction, centrifugation, and specialized ultrafiltration techniques have been explored and have been exploited commercially to a limited extent. Yield efficiency diagrams that relate juice yields to mash feed rates provide a mechanism for comparing presses and other processes such as enzyme treatments or decanter centrifuges for efficiency under a stated set of circumstances. Diffusion extraction is capable of removing 90 to 94% of soluble solids from properly prepared apple slices, but the resulting juice is diluted with extraction water and is high in extracted tannins. Concentration is necessary to obtain juice solids equivalency, and the resulting juice has sour/astringent flavors that must be removed with tannin absorbants to provide acceptable flavor. Currently, decanter centifuges are used commercially and have provided an alternative to presses under certain circumstances. When naturally colored and flavored (unoxidized) juices are desired, the decanter provides a useful alternative to presses because it is easily inert gas blanketed. Utilization of a metallic ultrafilter as a press has been patented but has not achieved commercial utilization. The technical literature describing the application of these juice extraction juices, primarily to apples, is reviewed extensively.

Physiological persistence of paclobutrazol on the ‘Tommy Atkins’ mango (Mangifera indicaL.) under rainfed conditions

SummaryTo investigate the feasibility of using paclobutrazol (PBZ) to control chemically mango tree size under rainfed conditions, the physiological persistence of soil applied PBZ on the vegetative growth, flowering behaviour, nutritional status, fruit set and quality of ‘Tommy Atkins’ mango was assessed for three consecutive years. A single application of PBZ (0, 2.5, 5,10,15, 20, and 40 g per tree) was made after harvest in June, 1990. Each dosage was dissolved in 2 1 of water and applied in a 15 cm depth trench at 1.5 m around the tree. Shoot length was significantly reduced only with 10 g PBZ per tree and greater concentrations. PBZ at 20 and 40 g per tree drastically reduced vegetative growth for a year after treatment. The effect of 10 g PBZ per tree on shoot growth was modest and lasted one year. With the exception of 40 g PBZ per tree, the effect of any level of PBZ on shoot length disappeared by year three. Increases in PBZ levels increased the earliness of flowering from 16 d (2.5 g PBZ per tree) to 40 d (40 g PBZ per tree) in the first year. For the second year after treatment, the effect of PBZ on time to flowering started to decline and, with the exception of 15 and 40 g PBZ per tree, earliness of flowering disappeared by year three after treatment. PBZ levels from 2.5 to 20 g per tree did not affect the number of mature fruit per m2 of canopy during the three experimental years. PBZ at 40 g per tree resulted in the lowest production of mature fruits for the first two years after application. However, for the third year this treatment produced most mature fruit per m2 of canopy. All PBZ rates decreased average fruit weight, but, the smallest fruits were produced with 15, 20 and 40 g PBZ per tree. Total soluble solids of fruit juice were not affected at low PBZ-rates (2.5 and 5 g per tree), but they were significantly higher with 10 g PBZ per tree and greater concentrations. PBZ at 10 g per tree and above drastically reduced leaf P and Ca content. A similar reduction was found for Mg with levels of 15 g PBZ per tree and above. No significant changes were detected in the leaf content of N and K. The use of 10 g PBZ per tree may have a dual effect, as it may reduce tree size and induce early flowering. To keep this effect, we speculate that under rainfed conditions, a single application of 10 g PBZ per tree should be followed by a reapplication with 10 or 5 g per tree every two years.

Evaluation of in-line sensors for prediction of soluble and total solids/moisture in continuous processing of fruit juices

Three inline sensors: Near-infra red (NIR) (Protonics P-112, Katrina Inc, Hagerstown, MD); Guided Microwave (Epsilon Industrial Inc, Austin, TX) and Maselli refractometer (Maselli Measurements Inc, Stockton, CA) were evaluated for continuous measurement of soluble and total solids/total moisture in continuous processing of (8–16 Brix) apple, grape, pear, apple-cherry and apple-banana juices in a pilot scale processing unit. Experiments were conducted in the temperature range 21–65 °C, back pressure of 0–204 kPa, flow rate of 0.756–4.536 kilolit/h, and acidity of 0.3 to 0.6% malic acid, and pH range of: 3.2–3.9. The sensors were calibrated by off-line measurement of soluble solids from an Abbe refractometer and total solids/moisture by standard vacuum oven method. The process temperature was found to have great effect on the prediction of these sensors. The effects of acidity, back pressure and flow rate were negligible. High correlation coefficients were obtained for calibration curves of the soluble and total solids in different juices. Maselli refractometer gave excellent results for soluble solids under different operating conditions. NIR Katrina analyser and GM Epsilon spectrometer gave good results for soluble and total solids. The sensors were found to give reproducible results after prolonged use and were not found to have any deposits or buildups. The present research shows that these sensors can satisfactorily be used for in-line processing of different juices in industries.

Trunk strangulation and winter heating effects on fruit size, internal quality and maturation of ‘Tosa Buntan’ pummelo grown in a plastic house

SummaryThe effects of trunk strangulation and winter heating on fruit growth, internal quality and maturation were studied. Strangulation of the trunk with a steel wire (1.6 mm diameter) was performed to the depth of the wire diameter in mid-October 1992. A significant increase in fruit size took place one month after treatment. Stomatal conductance, transpiration and net photosynthetic rates of the leaves were significantly decreased by trunk strangulation, but degreening of the fruit rind was not affected. Specific dry weight of the spring leaves significantly increased 57 d after treatment. the consequent increase of total soluble solids (TSS) in juice was attributed to an increase in the sucrose content, and occurred two months after imposing the treatment. The decrease in titratable acidity (TA) was ascribed to the decrease in the citric acid (CA) concentration, while malic acid (MA) increased from mid-October to mid-December and decreased thereafter. As malic acid content was significantly increased...

Studies on jicama juice processing

Juice was extracted from jicama (Pachyrrizus erosus Urban) and clarified using a 10,000 daltons molecular weight cut-off membrane to improve its stability. Ultrafiltered juice was tested for general composition and Hunter color. Ultrafiltration (UF) retentate and UF permeate showed some changes, compared to fresh juice, in total and soluble solids, total sugars, and nitrogen, whereas ash and pH remained constant. Hunter color of juice samples exhibited some variation by UF. Results suggest that UF has potential to produce jicama juice with desirable and stable aroma and flavor.

Response of `Reliance' Table Grapes to Canopy Management and Ethephon Application

Canopy management and ethephon application (100 mg·liter-1 2 weeks after veraison) were investigated for 2 years as possible ways to improve color and overall quality of `Reliance' grapes (Vitis spp.). Canopy management consisted of leaf removal, shoot positioning, and cluster thinning. Grapevines were subjected to one of two levels of leaf removal and one of two levels of preharvest ethephon spray and were either thinned to a basal cluster or nonthinned. Thinning and ethephon advanced harvest dates by 5 to 8 days and 2 to 3 days, respectively. In 1989, berry weight was increased by thinning but was not affected by leaf removal or ethephon. Leaf removal (direct sun exposure) of thinned and nonthinned treatments increased “L” values (lighter colored fruit) in 1989. In 1990, leaf removal, ethephon, and thinning resulted in higher “L” values. The “a” values were significantly increased by leaf removal in 1989 and 1990 and by thinning in 1989, a result indicating increased skin redness. Exposed clusters of nonthinned treatments had significantly higher “b” values due to more yellow fruit in 1989 than in 1990. Ethephon increased “b” values in thinned and nonthinned treatments. In 1990, leaf removal increased “b” values. Thinning resulted in more evenly colored, redder fruit. Leaf removal caused a lightening and yellowing of the skin. Juice from leaf removal treatments in 1990 had significantly higher “L”, “a”, and “b” values. Ethephon significantly increased the “a” value of juice in 1989, and leaf removal significantly increased the “b” value in 1989. The percent soluble solids of juice was generally decreased by ethephon and increased by leaf removal and thinning. Titratable acidity was decreased by leaf removal and ethephon and increased by thinning in both years. Leaf removal decreased berry pH in 1990. Thinning increased coloration, and direct exposure to light decreased coloration. The results with ethephon were not conclusive. Chemical name used: 2-chloro-ethyl-phosphonic acid (ethephon).