Effect of hot air treatment on quality and ripening of Chinese bayberry fruit

BACKGROUND: Postharvest decay and softening are the major factors limiting the extension of storage life of Chinese bayberry fruit. To evaluate the effects of hot air treatment (HAT) on Chinese bayberry fruit, fruits were stored at 2 °C after exposure to 20 °C (control), 40 °C (HAT₄₀), 45 °C (HAT₄₅) or 50 °C (HAT₅₀) hot air for 3 h. The effects of HAT on firmness, disease incidence, soluble solid content (SSC), titratable acidity (TA), respiration, ethylene production, pectic substances and activities of pectinmethylesterase (PME) and polygalacturonase (PG) were examined. RESULTS: HAT inhibited decrease in firmness, SSC and TA and retarded increase in disease incidence, while it promoted decrease in respiration rate and ethylene production. HAT suppressed the activities of PME and PG, which resulted in delaying the depolymerisation of chelator‐soluble and alkali‐soluble pectic substances and reducing the increase in water‐soluble pectic substances compared with control fruits. CONCLUSION: The present findings show that HAT can maintain postharvest quality and delay ripening of Chinese bayberry fruit and suggest that HAT could be considered for commercial use to extend the postharvest life of Chinese bayberry fruit. Copyright © 2008 Society of Chemical Industry     

Antibacterial Action of Haw Pectic Oligosaccharides

Haw pectic oligosaccharides, lactic acid, sodium lactate, and tea polyphenol showed dose and pH dependent antibacterial activity against E. coli. The activity of haw pectic oligosaccharides could be enhanced by combination with lactic acid, sodium lactate, or tea polyphenol. However, combination of haw pectic oligosaccharides with nisin resulted in no significant enhancement of antibacterial activity against E. coli. These results revealed that haw pectic oligosaccharides is valuable as a food preservative, and lactic acid or sodium lactate could be used to enhance its antibacterial activity, allowing for further improvement in its efficiency, likely leading to a reduction in the dosage necessary for food preservation.     

Evaluation of the extraction efficiency for polyphenol extracts from by‐products of green kiwifruit juicing

The health benefits of fruits are attributable in part to their bioactive components such as phenolics and pectic polysaccharides. By‐products derived from kiwifruit processing can be a good source of such bioactive compounds. Extracts were produced using different concentrations of ethanol in water (0%, 30%, 50%, 74% and 96% v/v) from by‐products (skin, residue and pulp) of the green‐fleshed kiwifruit (Actinidia deliciosa‘Hayward’) juicing process. The amounts of phenolic compounds and uronic acid (UA) as well as the phenolic composition in each extract were determined. Results show that different by‐products contained different concentrations of phenolics and pectic polysaccharides. Based on total phenolic contents, 96% v/v ethanol appeared to be the best extraction medium. The 30% or 74% ethanolic dilution was the second best medium for phenolic extraction from skin and pulp/residue, respectively. Water was a good medium for extracting satisfactory quantities of phenolics as well as the highest concentration of pectic polysaccharides. Phenolic profiling by high‐performance liquid chromatography (HPLC) was used to detect individual phenolic compounds in an extract. Results using HPLC showed that alkali pre‐treatment has improved the extraction efficiency of phenolics as a function of alkali concentration, fruit tissue type, extraction media, by‐product preparation method, and class of polyphenols. As a result more efficient methods for both extraction and characterisation of polyphenols could be evaluated.     

Bioactive phytochemicals, nutritional value, and functional properties of cape gooseberry (Physalis peruviana): An overview

Exotic fruits play an important role in nutrition as an excellent base for low calorie and dietetic products. Highly valued for its unique flavor, texture and color, recent research has shown cape gooseberry (Physalis peruviana) to be high in many beneficial compounds. The diversity of functional applications to which P. peruviana can be put gives this fruit great importance. The food industry has used cape gooseberry in different products including beverages, yogurts and jams. With the rapidly growing popularity of this unique fruit it is important to have a comprehensive reference for its nutritional benefits. This review provides a valuable source for current knowledge on bioactive phytochemicals and further development of P. peruviana for functional foods as well as nutraceutical and pharmaceutical industries.     

Firmness and Cell Wall Characteristics of Pasteurized Jalapeño Pepper Rings as Affected by Calcium Chloride and Rotary Processing

Rotary processing resulted in more uniform heat penetration and texture retention throughout the container than resulted after nonagitated processing. Localized softening in nonagitated peppers was due to prolonged heating at the top of the container, which hydrolyzed large molecular weight pectic substances (chelator and nonextractable) to more soluble forms. Calcium improved the texture by maintaining greater levels of insoluble pectic substances (chelator, dilute alkali and nonextractable) and reducing pectin solubilization. The combination of rotary processing and calcium chloride treatment resulted in a product with fresh-like, uniform texture throughout the container.     

RHEOLOGICAL BEHAVIOR AND PHYSICOCHEMICAL CHARACTERISTICS OF GOLDENBERRY (PHYSALIS PERUVIANA) JUICE AS AFFECTED BY ENZYMATIC TREATMENT

Goldenberry (Physalis peruviana) juice was prepared and enzymatically treated with two dosages (300 and 600 ppm) of Pectinex Ultra SP‐L, then, the juice was concentrated to 30 and 40°Brix. Rheological properties of juices were studied at a wide range of temperatures (5 to 100C) and shear rate range from 0.3 to 100/s using Brookfield Digital Viscometer. The Herschel–Bulkley, Casson and Bingham rheological models were applied to describe the rheological properties of different juices. These properties are key parameters required to solve food industry problems in numerous areas such as quality control, evaluation of consumer acceptance and texture. The results indicated that juice concentrates behave as non‐Newtonian fluids (pseudoplastic) and have a definite yield stress. The Bingham and Casson, plastic viscosity, yield stress, consistency index and flow index decreased with increasing enzyme dosage and temperature. The effect of temperature on the viscosity described by means of an Arrhenius‐type equation. The activation energy for viscous flow depends on the total soluble solids. Moreover, sensory evaluation for juices was carried out. In consideration of industrial utilization, detailed knowledge on the rheological and physicochemical characteristics of cape gooseberry juice is of major importance.     

Degradation characteristics of isolated and in situ cell wall lucerne pectic polysaccharides by mixed ruminal microbes

Two pectic polysaccharide fractions were isolated form lucerne (Medicago sativa L) leaves and used in fermentation experiments with mixed ruminal microbes. Both fractions were similar in chemical composition, containing galacturonic acid (52-58 mol%) and the neutral sugars arabinose (14-18 mol%), galactose (6-8 mol%) and rhamnose (8-12 mol%). Fermentation of both fractions was rapid and complete with a half-life of approximately 4 h. Production of total volatile fatty acids matched the degradation profile reaching a maximum level shortly after the rate of degradation began to decrease. The fermentation characteristics of citrus pectin and polygalacturonic acid were similar to those of the lucerne pectic fractions but galacturonic acid was much slower in its rate of degradation while soluble arabinogalactan from larchwood was virtually undegraded. Leaves of early bud stage lucerne and lower nodes and internodes of stems from full bloom lucerne were also fermented by mixed ruminal microbes. Pectic polysaccharides were rapidly and extensively degraded from both tissues. Initial rates were faster for leaves than for stems and the extent of pectic degradation was greater in leaves (8% residual) than in stems (17% residual). Selection of forage lines with increased pectic polysaccharides would provide greater amounts of rapidly available energy that could result in more efficient utilisation of the rapidly degraded protein in lucerne.     

Chinese gooseberry: Seasonal patterns in fruit growth and maturation,ripening, respiration and the role of ethylene

Fruits of Chinese gooseberry (Actinidia chinensis Planchon, cv. Bruno) were harvested and respiration rates and other attributes were measured at regular intervals throughout the season. The fruit matured at about 23 weeks after anthesis as shown by patterns of respiration, response to ethylene treatment and changes in texture and content of soluble solids. Fruit growth followed a unique triple sigmoid curve. Natural ripening showed the fruits to be of climacteric type but, although associated with a peak of ethylene production, the respiratory pattern was somewhat atypical and initiation of ripening within any lot of uniform fruits was very variable. Ethylene treatment stimulated ripening in fruits of all ages, but a large induced respiratory peak was seen only in immature fruits. The physiological observations confirmed present horticultural practices and provide a basis for development of objective enforceable quality grades.     

Yield,earliness and fruit quality of pepino clones and their hybrids in the autumn–winter cycle

The success of the pepino (Solanum muricatum Aiton) as a new crop for intensive horticultural areas relies on shortening the growing cycle and on securing a high standard of fruit quality. Irrigation with saline water and ethephon sprayings could be useful in achieving these goals. Two consecutive pepino crops consisting of two hybrids and their four parents were grown in the autumn–winter cycle. Plants were irrigated with water having electrical conductivities of 3 or 8 dS m⁻¹ and full sized fruits were sprayed with ethephon at 0 or 500 mg l⁻¹ . Salinity reduced yield and fruit size, although this effect was less important in the hybrids, which showed heterosis for yield characters. Overall, yields and fruit size of hybrids irrigated with saline water were greater than in the parents irrigated with non‐saline water. Ethephon had no effect on yield characters. Salinity and ethephon improved earliness. In most clones combination of salinity and ethephon shortened the growing cycle by 1 month. Salinity improved fruit quality as it increased the soluble solids content (SSC) and dry matter (DM) in all clones, and titratable acidity (TA) in some cases. Ethephon sprayings had no marked effects on quality characters, except for parental clone 9‐1 in which ethephon treated fruits had a lower SSC and TA. Organoleptic tests conducted on the best flavoured clones (0‐8 and 6‐10) showed that salinity improved fruit aroma and flavour although not texture, while ethephon had no effects. Results show that irrigation with saline water and ethephon sprayings improve earliness and fruit quality without dramatic yield depressions, especially in the hybrid clones. © 1999 Society of Chemical Industry     

Cell wall compositions of raw and cooked corms of taro (Colocasia esculenta)

The monosaccharide compositions of parenchyma cell walls of raw and cooked corms of taro, Colocasia esculenta cv Tausala Pink, were determined. The cell wall constituents were sequentially extracted using CDTA, Na₂CO₃, 1 M KOH, 4 M KOH and water to leave a final residue (α‐cellulose). The monosaccharide compositions of the cell walls and cell wall fractions from the raw and cooked corms were consistent with the presence in these cell walls of large amounts of cellulose and pectic polysaccharides. The monosaccharide composition of the cell walls of the raw corms resembled the monosaccharide compositions of primary cell walls of other non‐commelinoid monocotyledons and dicotyledons. Cooking of the corms resulted in alteration of the cell walls, with solubilisation of pectic polysaccharides occurring earlier in the sequential fractionation and possibly changes in the extractability of xyloglucans and/or xylans. © 2000 Society of Chemical Industry     

Physical and chemical changes in developing strawberry fruits

Strawberry fruits of thevariety Red Gauntlet were harvested at 7 day intervals after petal fall. Changes in fruit weight, percentages survival on the plant, chlorophyll: carotenoid and anthocyanin, titratable acid, pH of extracts and sugar content were measured. Also changes in soluble and total pectic polysaccharides in alcoholinsoluble residues of harvested fruits were followed during development. Fruit growth was not exponential and in later stages of growth the falling survival rate was correlated to fruit softening. Net synthesis of chlorophyll and carotenoid pigments took place up to 28 days and anthocyanin synthesis commenced 28 to 35 days after petal fall. The sugar content of berries increased with time and titratable acid concentrations increased slightly during development, falling in ripening fruits. The specific viscosity of soluble pectic polysaccharides fell from 28 days after petal fall. There was net synthesis of polyuronide but not neutral polysaccharide during the development of fruits and the amount of insoluble pectic polysaccharide became small and relatively constant compared with the amount of soluble polysaccharide by 21 days after petal fall. Fruits undergoing senescence lost almost all their insoluble pectic polysaccharides. The developmental processes taking place in growing fruits, especially with respect to changes in cell wall structure, and the relevance of results to fruit storage are discussed.     

Methyl jasmonate reduces chilling injury symptoms and enhances colour development of ‘Kent’ mangoes

Treatment of mango (Mangifera indica cv ‘Kent’) fruits with methyl jasmonate (MJ) vapour for 20 h at 20 °C reduced chilling injury (CI) symptoms and enhanced skin colour development. MJ at 10^?4 M was the most effective concentration for reducing CI and decay in fruits stored at 5 °C followed by 7 days at 20 °C (shelf‐life period). The use of 10^?5 M MJ enhanced yellow and red colour development of mangoes stored at 20 °C. These fruits possessed higher L*, a* and b* values than untreated fruits and those treated with 10^?4 M MJ. Ripening processes were inhibited by cold storage (5 °C) in control fruits. After cold storage and shelf‐life period, fruits treated with 10^?5 M MJ ripened normally and contained the highest total soluble solids (TSS). These fruits also maintained higher sugar and organic acid levels than fruits subjected to other treatments. We concluded that MJ treatment could be used to reduce decay and CI symptoms and also to improve colour development of mango fruits without adversely affecting quality. © 2001 Society of Chemical Industry     

Effects of Ultraviolet Light (UV‐C) and Heat Treatment on the Quality of Fresh‐Cut Chokanan Mango and Josephine Pineapple

The effects of ultraviolet (UV‐C) and medium heat (70 °C) treatments on the quality of fresh‐cut Chokanan mango and Josephine pineapple were investigated. Quality attributes included physicochemical properties (pH, titratable acidity, and total soluble solids), ascorbic acid content (vitamin C), antioxidant activity, as well as microbial inactivation. Consumers’ acceptance was also investigated through sensory evaluation of the attributes (appearance, texture, aroma and taste). Furthermore, shelf‐life study of samples stored at 4 ± 1 °C was conducted for 15 d. The fresh‐cut fruits were exposed to UV‐C for 0, 15, 30, and 60 min while heat treatments were carried out at 70 °C for 0, 5, 10 and 20 min. Both UV‐C and medium heat treatments resulted in no significant changes to the physicochemical attributes of both fruits. The ascorbic acid content of UV‐C treated fruits was unaffected; however, medium heat treatment resulted in deterioration of ascorbic acids in both fruits. The antioxidants were enhanced with UV‐C treatment which could prove invaluable to consumers. Heat treatments on the other hand resulted in decreased antioxidant activities. Microbial count in both fruits was significantly reduced by both treatments. The shelf life of the fresh‐cut fruits were also successfully extended to a maximum of 15 d following treatments. As for consumers’ acceptance, UV‐C treated fruits were the most accepted as compared to their heat‐treated counterparts. The results obtained through this study support the use of UV‐C treatment for better retention of quality, effective microbial inactivation and enhancement of health promoting compounds for the benefit of consumers.     

Effects of Ethephon on Fresh In‐Husk Walnut Preservation and its Possible Relationship with Phenol Metabolism

Fresh walnuts (Juglans regia L.) are in demand due to their high nutrition value and unique flavor of the kernel. In this study the effects of ethephon on decay control and kernel quality of fresh walnuts and its possible relationship with phenolic metabolism were investigated. Fresh in‐husk walnuts treated with 0, 10, 500, and 8000 mg/L ethephon were stored at 0 ± 0.5 °C for 42 d. Decay incidence, total phenolic (TP) compounds, phenylalanine ammonialyase (PAL), polyphenol‐oxidase (PPO), and peroxidase (POD) activities of green husks, and acid values (AV) and peroxide values (PV) of kernels were assessed at 6‐d intervals. The respiration rate of the whole walnut was assessed at 3‐d intervals. Treatment with 500 mg/L ethephon enhanced respiration, reduced the decay index, and inhibited PPO and POD activity and browning of green husks, and also promoted PAL activity and TP content of green husks. This treatment also reduced the PV and AV of kernels. A concentration of 10 mg/L ethephonhad similar, but weaker, effects on walnuts. Treatment with 8000 mg/L ethephon, however, had opposite effects. These data indicate ethephon treatment at a proper concentration can extend storage life and maintain kernel quality of fresh in‐husk walnuts through the manipulation of phenolic metabolism.     

Determination of Terpene Profiles in Potential Superfruits

The aim of this work was to characterize and compare the profiles of volatile terpenes in four potential superfruits. These profiles were determined using headspace solid-phase microextraction coupled with comprehensive two-dimensional gas chromatography linked to time-of-flight mass spectrometry. The proposed technique allowed the separation and identification of 79 terpenes present in cape gooseberry, crabapple, cherry silver berry, and scarlet hawthorn. The preliminary compound identification was based on the analysis of deconvoluted mass spectra and a comparison of the calculated linear retention indices with their values reported in the scientific literature. The compound identification was performed using the available standards. Also, a semi-quantitative total ion chromatogram-based analysis was performed. The richest terpene profile was identified in cape gooseberry (62 terpenes), where the terpene fraction constituted about 14% of total volatile fraction.     

Gamma irradiation of cowpea (Vigna unguiculata L. Walp) seeds: effect on colour,cooking quality and pasting characteristics

Cowpea seeds were treated to various gamma irradiation doses, and their colour, cooking quality and pasting properties studied. Irradiation at 50 kGy resulted in significant browning (indicated by decreases in L colour value) of cowpea seeds. At 2 and 10 (but not at 50) kGy, irradiation led to significant reduction in cooking time of cowpea seeds possibly through irradiation‐induced degradation of starch and pectic substances (indicated by decreases in peak and final viscosities) leading possibly to enhanced heat and mass transfer within the seed cotyledon and cell wall, respectively. At 50 kGy, the cooking time of cowpea seeds was prolonged significantly owing possibly to extensive polymer cross‐linking occurring within the seeds at this high dose. Splitting of cowpea cotyledons during cooking decreased significantly at 50 kGy, but was unaffected at 2 and 10 kGy. Irradiation resulted in significant leaching of nutrients from cowpea seeds during cooking in a dose‐dependent manner.     

Pectic oligosaccharides production from orange peel waste by enzymatic hydrolysis

Orange peel waste (OPW) was evaluated as a raw material for the enzymatic production of pectic oligosaccharides. In a preliminary step, free sugars and other water‐soluble compounds were extracted from OPW to obtain a substrate for enzymatic hydrolysis (EHS), to achieve two objectives: (i) removal of sugars and impurities, and (ii) production of a sugar‐rich stream suitable for further utilisation, according to the ‘biorefinery’ philosophy. EHS was treated with hydrolytic enzymes (pectinases and cellulases), and the effects of selected operational variables (enzyme charges and reaction time) on selected dependent variables (measuring the conversions of polysaccharides into mono‐ and oligosaccharides, and liquor recovery) were assessed. Mathematical models were developed for this purpose. Under selected conditions, the models predicted that 100 kg of EHS yielded 7.5 kg of gluco‐oligosaccharides, 4.5 kg of galacto‐oligosaccharides, 6.3 kg of arabino‐oligosaccharides and 13 kg of oligogalacturonides (contained in 991.6 kg of liquor).     

Effects of stage II and postharvest deficit irrigation on peach quality during maturation and after cold storage

Effects of regulated deficit irrigation (RDI) on the quality of a mid–late maturing peach (Prunus persica L Batsch cv Andross) were determined at commercial harvest as well as 1 week before (early pick‐up) and after 1 week of cold storage. Respiration and ethylene evolution were measured during 96 h on fruits sampled at early pick‐up and at harvest. Fruits from a well‐watered irrigation treatment (Control) were compared with a treatment of RDI during stage II of fruit growth (RDI‐SII) and with RDI applied postharvest (RDI‐PH). A fourth treatment received a combination of deficit irrigation applied during stage II and postharvest (RDI‐SII‐PH). Higher soluble solids content (SSC) amd SSC/titratable acidity (TA) ratio for RDI‐SII were already noted at early pick‐up and these differences were enhanced after cold storage (RDI fruits having higher SSC, lower TA and higher SSC/TA ratio than Control fruits). This improvement in quality (high SSC/TA ratio) was also correlated with a more reddish colouration in the fruit skin. Moreover, ethylene production indicated different behaviour of the physiological evolution for fruits from the different treatments. Copyright © 2004 Society of Chemical Industry     

Effects of High Pressure and Heat Treatment on Pectic Substances and Related Characteristics in Guava Juice

Effects of high pressure treatment on guava juice pectic substances and related juice characteristics were investigated and compared with heat treatment. The viscosity and turbidity of guava juice pressurized at 600 MPa and 25°C for 10 min increased slightly; whereas the viscosity of juice heated at 95°C for 5 min decreased while turbidity increased. There were no apparent changes in water soluble, oxalate soluble and alkali soluble pectin in pressurized juice. However, heat treatment of juice decreased water and alkali soluble pectins and slightly increased oxalate soluble pectin. High pressure treatment resulted in no marked changes in pectic and cloud substances of guava juice, and maintained the natural viscous of the juice.     

Pectic polysaccharides during ripening of mango (Mangifera indica L)

The content of pectin decreased from 2.0 to 0.7% fresh weight (FW) and there was a concomitant increase in free galacturonic acid from 36 to 168 mg% FW during ripening of mango. Ion exchange chromatography on DEAE/cellulose resolved the pectic fraction into seven distinct peaks, with all of them showing a drastic decrease in pectin content and molecular weight as fruit ripening progressed, which indicated significant depolymerisation in vivo. Fraction I appeared to be an arabinogalactan‐type polymer, while fractions II and III were heterogalacturonans containing more than 60% galacturonic acid. Hydrolases implicated in pectin depolymerisation were polygalacturonase (PG), pectin methyl esterase (PME), galactanase, arabinanase and β ‐galactosidase. They all showed a climacteric peak in activity during ripening, except for PME which showed a continuous decrease in activity after an initial increase. These results are discussed in the light of fruit softening during ripening. Copyright © 2003 Society of Chemical Industry