Pulp Browning Research Articles

ERYTHORBIC ACID AND SODIUM ERYTHORBATE EFFECTIVELY PREVENT PULP BROWNING OF MINIMALLY PROCESSED ‘ROYAL GALA’ APPLES

This study aimed to evaluate the effect of erythorbic acid (EA), sodium erythorbate (SE) and kojic acid (KA) to control the pulp browning of minimally processed (MP) ‘Royal Gala’ apples. Physicochemical and sensorial properties of MP apples were evaluated during a shelf life testing. SE and EA resulted in the highest levels of phenolic compounds, antioxidant activity and PPO and POD inhibition. Sensorial analysis results revealed that SE and EA treatments preserved the flavor, odor, color, succulence, firmness and overall quality of MP apples for up to 9 days. In conclusion, both SE and EA are suitable antibrowning agents for MP ‘Royal Gala’ apples.

Effect of chilling temperatures on physiological properties, phenolic metabolism and antioxidant level accompanying pulp browning of peach during cold storage

The aim of this experiment was to assess the effect of chilling temperatures on the quality, phenolic metabolism as well as antioxidant capacity accompanying pulp browning (PB) development of peach fruit over the long-term refrigerated storage. Fresh peaches were exposed to chilling storage at 0, 2, 4, 6 °C for 30 or 50 d. Pulp browning index, TSS, TA, vitamin C, phenolics content and antioxidant activity were assessed, along with PAL and PPO enzymatic activity. Our results indicated that lower temperatures (0 and 2 °C) retarded the development of PB and maintained the fruit appearance during refrigerated storage. The storage life based on fruit quality was longer at 0 or 2 °C than at 4 or 6 °C. Additionally, peaches exposed to 4 or 6 °C accumulated higher amounts of phenolics and antioxidant activity than those exposed to 0 or 2 °C to overcome the more seriously cold stress. In conclusion, for short storage life or immediate consumption, keeping peach fruit at warmer temperature (4 or 6 °C) is favorable for obtaining high antioxidants. However, if the goal is extending the cold storage period of the fruit, keeping the fruit at 0 or 2 °C is recommended.

Effect of eugenol fumigation treatment on chilling injury and CBF gene expression in eggplant fruit during cold storage

The effect of eugenol (EUG) on chilling injury (CI) to eggplant fruit (Solanum melongena L.) was investigated. Eggplant fruit were pre-treated with 25 μL/L EUG, and then stored at 4 °C for 12 days. Results showed that EUG fumigation treatment effectively retarded the CI development, reduced pulp browning, weight loss, and malondialdehyde (MDA) content, and sustained soluble solids content (SSC) and proline content. Moreover, the activities of polyphenol oxidase (PPO) and peroxidase (POD) were inhibited by EUG. C-repeat/dehydration-responsive element binding factors (CBF) genes are transcription factors playing a critical role in cold acclimation. To illuminate the molecular regulation of EUG on chilling tolerance in eggplant fruit, a 1151 bp SmCBF gene was identified and the effect of EUG on SmCBF expression was determined by RT-qPCR. EUG resulted in a higher SmCBF expression. These findings suggested that EUG treatment had potential effect on alleviating CI in eggplant fruit.

Relationship between flesh browning and the activities of polyphenol oxidase, peroxidase and phenylalanine ammonia-lyase in feijoa fruit

Flesh browning is the main postharvest disorder limiting the storage life of feijoa fruit produced in southern Brazil. The aim of this study was to evaluate the relationship between the activity of polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonia-lyase (PAL) and incidence of flesh browning in five Brazilian genotypes of feijoa: cultivars 'Alcântara', 'Helena', 'Mattos' and 'Nonante', and the access 2316. Fruit of all genotypes were harvested at commercial maturity in 2013, and cold stored for 7 and 14 days (4±1°C/90±5% RH), followed by 48 h of shelf life (23±1°C/75±5% RH). The activities of PPO, POD and PAL and incidence of fresh browning were assessed at the harvest and after 7 and 14 days of cold storage (followed by shelf life). On average of all genotypes, the activity of PPO increased 29% from harvest to 7 days of cold storage, and 37% from 7 to 14 days of cold storage. PPO activity after 14 days of cold storage was highest in 'Mattos' and lowest in 'Helena'. POD activity was low in all genotypes and decreased from harvest until 14 days of cold storage. In all genotypes, PAL activity did not change from harvest until 7 days of cold storage but increased from 7 to 14 days of cold storage (by 11-28%) in 'Alcântara', 'Helena' and 'access 2316'. 'Mattos' had the highest PAL activity, which did not change from harvest until 14 days of cold storage. The severity of pulp browning after 14 days of cold storage (followed by shelf life) was higher in 'Mattos', 'Alcântara' and 'access 2316', and lower in 'Nonante' and 'Helena'. The results show that the occurrence of flesh browning in the fruit of feijoa genotypes cultivated in southern Brazil is associated fruit senescence, and related to the increase of PPO and PAL activities during storage (especially of PPO). POD activity was low in all genotypes of feijoa and, therefore, the enzyme seems to have little effect on the internal browning.

Comparative study of the banana pulp browning process of 'Giant Dwarf' and FHIA-23 during fruit ripening based on image analysis and the polyphenol oxidase and peroxidase biochemical properties.

This work presents a novel method to associate the polyphenol oxidase (PPO) and the peroxidase (POD) activities with the ripening-mediated color changes in banana peel and pulp by computational image analysis. The method was used to follow up the de-greening of peel and browning of homogenized pulp from 'Giant Dwarf' (GD: Musa AAA, subgroup Cavendish) and FHIA-23 (tetraploid hybrid, AAAA) banana cultivars. In both cultivars, the color changes of peel during the ripening process clearly showed four stages, which were used to group the fruit into ripening stages. The PPO and POD were extracted from pulp of fruit at these ripening stages, precipitated, and partially purified by gel filtration chromatography. Moreover, the pulp browning was digitally monitored after homogenization for a span time of up to 120min. The browning level was higher for GD than FHIA-23 tissues. This fact correlated with an 11.7-fold higher PPO activity in the GD cultivar, as compared with that of FHIA-23. POD activity was 8.1 times higher for GD as compared that that of FHIA-23.

<b>Evaluation of chemical characteristics and correlation analysis with pulp browning of advanced selections of apples grown in Brazil

In this research, the total phenolic content (TPC) and antioxidant capacity (FRAP and DPPH•× assays) of pulps and peels of advanced selection of apples grown in Brazil were investigated. The correlation analyses between the activity of polyphenoloxidase enzyme (PPO), vitamin C content, total titratable acidity, and color parameters were performed. The results indicated that the data differed significantly among the apple genotypes studied. The peels of the selection Epagri 170-91 and Epagri 170-25 showed the highest TPC and antioxidant capacities. In addition, the pulps of the Epagri 170-91 presented the highest TPC and antioxidant capacities, the lowest enzymatic browning, highest amount of vitamin C and lowest enzymatic activity when compared with other genotypes. The TPC and antioxidant capacities were significantly correlated in all genotypes analyzed. High correlation values between enzymatic browning and factors that affect the apple color were also found in all analyzed pulps, except between enzymatic browning and TPC. The results demonstrated that the enzymatic browning and TPC, as well as the antioxidant capacity and chemical characteristics, vary considerably depending on the apple genotypes and fruit tissues analyzed.

Physicochemical characterization and nutritional composition analysis of pineapple guava at three different ripening stages

Pineapple guava (Acca sellowiana [O. Berg] Burret) is a fruit with export and production potential in Colombia. However, there are few reports about its composition concerning physiological behavior throughout the different ripening phases. Intending to confront this situation, a study was proposed in order to evaluate the physicochemical properties and the nutritional composition of pineapple guava fruits in three different phases of ripening, determined by the weeks elapsed after anthesis, considering it undeveloped for week 17 (W17), ripe for week 20 (W20) and overripe from week 21 (W21). Pineapple guava fruits were preliminarily characterized, they underwent a bromatological analysis and their content of vitamin A and C content was established. The results showed a significant content of crude fiber and total carbohydrates in the three evaluated phases. There was also a decrease in the neutral detergent fiber of 38% between W17 and W21. The highest level of vitamin C was reported in W17 (67.82 mg ascorbic acid/g dry sample), as well as for vitamin A (12.65 mg β-carotene/g dry sample). In a physical-chemical characterization, the existence of a particular physiological behavior is possible because of the development in size and mass of the fruit after physiological ripening. Additionally, the calcium and reducing carbohydrate content can be associated with the pulp browning phenomenon. Clearly, pineapple guava is a promising fruit thanks to its nutritional properties, according to the current consumption tendencies.

Polyphenol Oxidase in Pawpaw (Asimina triloba [L.] Dunal) Fruit Pulp from Different Varieties

Pawpaw (<em>Asimina triloba</em> L. Dunal) is a tree fruit from the tropical Annonaceae family. Pawpaw currently has very limited commercial production because of its high perishability. Polyphenol oxidase (PPO) is responsible for enzymatic browning in pawpaw pulp. The objective of this research is to characterize PPO extracted from different pawpaw varieties. With respect to PPO activity, six of the varieties (Taytwo, Rebecca’s Gold, NC-1, Overleese, Rappahannock, and Green River Belle) exhibited PPO activity that was statistically higher than Quaker’s Delight and Lynn’s Favorite. The other four varieties (SAA Zimmerman, Shenendoah, KSU-Atwood, IXL) exhibited PPO activity that was not significantly different from each other or Quaker’s Delight and Lynn’s Favorite, but were significantly lower than Taytwo, Rebecca’s Gold, and NC-1. Kinetic parameters (Vmax, Km) and their ratio can be used to relate enzyme velocity with substrate affinity. Varieties that exhibited a high ratio, i.e. a very active enzyme due to a high Vmax and/or a low Km, are Rebecca’s Gold, Taytwo, NC-1, and KSU-Atwood). The results presented indicate that certain varieties exhibit conditions that suggest PPO could have a lower inherent impact on tissue browning, especially Lynn’s Favorite, Green River Belle, IXL, SAA Zimmerman, and Overleese. On the other hand, certain varieties (Taytwo, Rebecca’s Gold, NC-1, and perhaps KSU Atwood) exhibit PPO activity, Vmax, and Km values that suggest inherently high PPO activity and thus increased potential for browning. Overall, understanding PPO activity may help to explain post-harvest discoloration of pawpaw pulp and aid the commercial selection of more shelf-stable varieties.

Exogenous Application of Oxalic Acid Delays Pericarp Browning and Maintain Fruit Quality of Litchi cv. “Gola”

The present study was conducted to investigate the influence of oxalic acid on pericarp browning, biochemical quality, antioxidative and enzymatic changes in litchi cv. “Gola” fruit under extended cold storage, which has not been studied extensively. Postharvest application of 2 mM oxalic acid reduced fruit weight loss and delayed pericarp browning by maintaining higher anthocyanin contents, as compared with control. Activities of polyphenol oxidase and peroxidase enzymes in litchi peel as well as pulp tissues were reduced in fruit treated with 2 mM oxalic acid during 28 days of cold storage. Activities of antioxidative enzymes (superoxide dismutase and catalase) and level of total phenolic contents and total antioxidants in litchi peel as well as pulp tissues were significantly higher in 2 mM oxalic acid-treated fruit. In conclusion, postharvest application of 2 mM oxalic acid significantly delayed pericarp browning and maintained better quality of litchi cv. “Gola” fruit during cold storage. Practical Applications Pericarp browning of litchi fruit is associated with postharvest oxidative stress, which deteriorates its quality, long-term storability and commercial value. Postharvest application of oxalic acid has been found to be a useful strategy to overcome the issue of pericarp browning and enhance antioxidative potential of litchi under low temperature storage; thereby, applicable to commercial supply chains for domestic and export markets. Furthermore, this study may facilitate in understanding the changes in antioxidative potential and enzymatic activities during cold storage with gradual browning in pulp as well as peel tissues of litchi.

Beneficiamento pós-colheita de lima ácida 'Tahiti' afeta sua qualidade e conservação

RESUMO: O objetivo deste trabalho foi determinar os efeitos das etapas de beneficiamento pós-colheita de lima ácida 'Tahiti' na sua qualidade e conservação. Foram utilizados frutos colhidos por torção, em estádio de maturação fisiológica e beneficiados de acordo com o procedimento para frutos de exportação. Foram estabelecidos cinco pontos de coleta de frutos ao longo do processo de beneficiamento, os quais correspondem aos tratamentos estudados: "Campo"- coleta diretamente na planta; "Recepção"- na área de recepção da unidade de beneficiamento; "Repouso"- após a primeira etapa do beneficiamento; "Beneficiamento completo"- após o beneficiamento completo; e "Centro de comercialização"- na recepção do centro de comercialização. Foram conduzidas análises físicas e químicas durante 20 dias de armazenamento a 22±2ºC e 70±5% de UR. Os frutos que passaram pelo processo de beneficiamento completo e os que foram coletados no centro de comercialização apresentaram maior perda de massa fresca, maior incidência de oleocelose, menor porcentagem de frutos em condição de comercialização ao final do período de armazenamento, escurecimento da polpa e maior degradação de ácido ascórbico. A qualidade e conservação dos frutos de lima ácida 'Tahiti' foram prejudicadas pela movimentação, manipulação e injúrias mecânicas que ocorrem durante as etapas de beneficiamento pós-colheita.

Lyophilization of Avocado (Persea americana Mill.): Effect of Freezing and Lyophilization Pressure on Antioxidant Activity, Texture, and Browning of Pulp

Effects of both previous freezing (−26 and −80°C) and lyophilization (0.12, 0.37, and 1.07 mbar) conditions on drying kinetics, antioxidant activity, texture, and browning index of avocado pulp were evaluated. Vacuum pressure was found to have less effect on the lyophilization process than previous freezing temperature. Samples frozen initially at − 80°C required a longer lyophilization time. The best fittings for the drying kinetics of the avocado were obtained using the Page equation. The processing directly affected the antioxidant activity of the avocado pulp. Both the lipophilic and the hydrophilic fraction of the freeze-dried pulp decreased antioxidant activity, regardless of the applied pressure or freezing type. The hardness of the fresh avocado (0.93 N) was higher than the freeze-dried samples frozen in a conventional freezer (0.49 N) and their adhesion was greater than all of the freeze-dried samples. Freeze-dried pulps showed higher browning index than fresh avocado pulp (135.3).

Grafting influences phenolic profile and carpometric traits of fruits of greenhouse-grown eggplant (Solanum melongena L.).

The influence of eggplant grafting on tomato rootstock was evaluated during the two growing seasons. Yield, quality traits, and individual phenolics in fruits were assessed. Three commercial varieties and one landrace were used as scions. Grafting significantly increased eggplant yield and decreased the presence of calyx prickles. The effect of grafting on the accumulation of major phenolic constituents in eggplant fruit was inconsistent: in the year with less solar radiation and lower mean daily air temperatures, grafting decreased phenolic content in commercial variety/rootstock fruit and increased the content in landrace/rootstock fruit. An opposite effect in the latter combination was observed in the year with improved conditions for eggplant cultivation. The browning potential of fruit pulp was highly dependent on variety/landrace and partly also on grafting combination. Differences in correlations between phenolic constituents and browning potential (positive for varieties and negative for landrace) could also be ascribed to the importance of other antioxidants for diminished eggplant pulp browning.

Effect of 24-epibrassinolide treatment on the metabolism of eggplant fruits in relation to development of pulp browning under chilling stress.

This study aims to investigate the effect of 24-epibrassinolide (EBR) on the metabolism in relation to development of chilling injury-induced pulp browning of eggplant fruit. The fruits were dipped for 10min in solutions containing 10μmM EBR and then stored at 1°C for 15days. Chilling injury index, weight loss, electrolyte leakage and malondialdehyde (MDA) content of control fruit increased during storage. Chilling injury improved phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD) activities, which are correlated with the increase of total phenolic content and pulp browning of eggplant fruit. The inhibition of pulp browning by EBR treatment was possibly attributed to preserving the cell membrane integrity, reducing total phenolic content, and decreasing PAL, PPO, and POD activities. These results suggest that EBR may inhibit chilling injury and pulp browning in eggplant fruit during cold storage.

Distribution, stability and fate of phenolic compounds in white and purple eggplants (Solanum melongena L.)

Eggplants rank among the vegetables richest in antioxidants, but little is known about the allocation, stability, and turnover of these metabolites. The distribution, accumulation and degradation of phenolic antioxidants in the inner and outer pulp of two commercially important eggplant types (white and dark purple), at harvest and after 14 and 30d of refrigerated storage under non-chilling conditions (10°C and 90% RH) were determined in this study. Chlorogenic acid (ChA) was histolocalized by fluorescence with 2-aminoethyl-diphenylborinate and the activity of phenolic compounds oxidizing enzymes (polyphenoloxidase, PPO and peroxidase, POD) as well as H2O2 concentration in both fruit regions was determined. During storage, dark purple fruit were more susceptible to dehydration and showed greater deterioration than white eggplants. Both genotypes accumulated higher sugar content in the inner pulp as opposed to acids, which were more concentrated in the outer region. At harvest, pulp antioxidant capacity was similar in both eggplant types. TEAC and DPPH assays and in situ localization, showed greater total antioxidants and ChA content in the core than in the outer pulp in both white and dark purple fruit. The stability of ChA was markedly different between genotypes. In white fruit, antioxidants increased during the first two weeks of storage, remaining stable afterwards. In contrast, in dark purple eggplants, phenolic compounds declined after an initial stage at which they accumulated. PPO and POD in vitro activities, associated mainly with fruit seeds, fibers, and vascular bundles did not correlate with pulp browning or loss of phenolic antioxidants. Instead, the reduction of ChA in the core of dark purple fruit was associated with increased production of H2O2. Results indicate that antioxidants are predominantly located in the inner pulp of eggplants regardless of the genotype, but are more stable in white fruit. Rather than being the result of browning reactions, substantial losses of phenolic antioxidants in whole eggplants under the recommended storage conditions likely result from seed coat development and vascular lignification in the immature fruit.

Effect of low temperatures on pulp browning and endogenous abscisic acid and ethylene concentrations in peach (Prunus persica L.) fruit during post-harvest storage

SummaryChanges in the severity of pulp browning, endogenous abscisic acid (ABA) and ethylene concentrations, and related gene expression in peach (Prunus persica L. ‘Bayuecui’) fruit stored at the biological freezing-point temperature (BFT; 1ºC), at 4ºC, or at room temperature (20ºC; as a control) were investigated.The results showed that fruit stored at room temperature showed climacteric changes in ethylene and ABA concentrations and in levels of expression of the corresponding ethylene synthetase genes (PpACS1, PpACO1) and the gene for a key enzyme of ABA synthesis (PpNCED), concomitant with a significant decrease in fruit firmness and an increase in juice yield. Meanwhile, two sucrose synthase genes (PpSUS1 and PpSUS2) were expressed at relatively low levels. However, fruit firmness decreased slightly and chilling injury (CI) increased significantly 40 d after storage (DAS) at 4ºC, with a significant accumulation of proline [from 8.33 µg g–1 (at t = 0 d) to 9.125 µg g–1 (at t = 40 d)]. In contrast, fruit firmness decreased slowly and pulp browning increased slightly 80 DAS at the BFT ( 1ºC), with a lower accumulation of proline than in fruit stored at 4ºC. The concentrations of soluble sugars and titratable acidity decreased during storage at 1ºC, 4ºC, or 20ºC, but there was a peak of soluble sugars at a late stage of storage at the BFT ( 1ºC). The fruit browning index was significantly and positively correlated (R 2 = 0.967) with ABA concentration. The decrease in ABA concentration in cold-stored fruit (at both 1ºC and 4ºC) inhibited ethylene production. Moreover, there was no significant correlation between CI in fruit and ethylene production. In conclusion, the decrease in ABA concentration reduced ethylene concentrations and inhibited the development of pulp browning, which resulted in an improved taste, but crisper fruit, when fruit were stored at the BFT (–1ºC).

Inhibition of pulp browning and quality maintenance of late peach cultivars

The purpose of this study was to identify the effect of delayed storage on the maintenance of the quality and on the control of pulp browning during cold storage of late peach cultivars. The fruit was harvested at the mature-green stage. All cultivars were exposed to temperatures of 20 ± 0.5oC and 75 ± 3% of moisture in a cold room for 0.24, or 48 hours. Afterwards, the peaches were kept at 0 ± 0.5oC and 92 ± 3% of R.H. for 28 days. In the end, the yellow pulp cultivars, regardless of temperature and length of delayed storage, did not present signs of internal browning and were of adequate quality for commercialization. When they were not subjected to delayed storage, the white pulp peaches presented pulp browning after 14 days of cold storage plus two days out of the cold room. From the results observed in the analysis of soluble solids, titratable acidity and decay development, these peaches showed an increased level of ripening. In both cultivars, delayed storage for 48 hours resulted in increased ripening and decay. Delayed storage for 24 hours was effective in controlling pulp browning and in maintaining the quality of the white pulp peach cultivars.

Changes in quality and phenolic antioxidants in dark purple American eggplant ( Solanum melongena L. cv. Lucía) as affected by storage at 0 °C and 10 °C

Many beneficial effects associated with fruit and vegetable consumption are related to the presence of antioxidants, which could be greatly affected by postharvest storage conditions. Eggplants or aubergines ( Solanum melongena L.) are among the top vegetables in terms of antioxidant content. In this work, we evaluated the effect of two postharvest temperature regimes on deterioration and antioxidants of dark purple American eggplants (cv. Lucía). Fruit were stored at 0 or 10 °C for 0, 3, 5, 10 or 14 d and weight loss, electrolyte leakage, chilling injury, and pulp browning were evaluated. We also followed DPPH and Folin–Ciocalteu reacting substances and the content of chlorogenic and quinic acid by HPLC. Although weight loss was reduced in fruit held at 0 °C, higher electrolyte leakage and chilling injury manifested as surface scalds and pulp browning were found. Antioxidants (AOX) measured with the DPPH radical and with the Folin–Ciocalteu reagent increased during the first 3 d of storage at 0 °C, but afterwards significant degradation was found. In contrast, a gradual but continuous accumulation of AOX was detected in fruit stored at 10 °C. The slow rate in the reaction between DPPH and eggplant samples suggested that the main changes during postharvest storage were due to modifications in phenolic compounds. The major phenolic detected by HPLC was chlorogenic acid (ChA), an ester between caffeic (CA) and quinic acids (QA), which accumulated in fruit maintained at 10 °C, increasing by 60% after 14 d of storage. No free CA was found at any storage temperature or time, suggesting that its biosynthesis is activated simultaneously with the production of ChA. Free QA showed minor changes at 0 °C as pulp lightness decreased, indicating that ChA rather than CA may be the main substrate for browning reactions. Changes in eggplant fruit antioxidants during storage at chilling and non-chilling temperatures are discussed.

Shelf life of minimally processed pineapples treated with ascorbic and citric acids

The purpose of this research was to determine the shelf life of minimally processed (MP) 'Pérola' pineapples treated with ascorbic acid (AA) and citric acid (CA) based on physical, chemical, sensorial and microbiological attributes. Slices were dipped into drinking water (control) or combined solutions of AA:CA (%) (1.0:0.5 and 1.0:1.0) with sodium hypochlorite (NaClO 20 mg L-1) for 30 seconds. The samples were conditioned in polyethylene terephtalate packages and stored at 4±1 °C per 13 days. The low peroxidase activity in the slices treated with antioxidant combinations was related to low pH values observed in these samples. The treatments 1.0:0.5 and 1.0:1.0 (AA:CA, %) favored maintenance of the initial a* values and avoided the pulp browning. The ascorbic acid increased more than double on the 2nd day in the treated slices. By the 4th day the CO2 values suggested a higher respiratory activity in the slices treated with anti-browning compounds. The antioxidant treatments did not produce detectable residual flavors in the MP pineapple. Regardless of microbiological safety during the 13 days of cold storage, the control slices can be kept by 6 days, afterwards the color and dehydration become strong enough to affect the appearance. On the other hand, MP 'Pérola' pineapples treated with 1.0:0.5 (AA:CA, %) and NaClO (20 mg L-1) can be stored for 8 days at 4±1 ºC, which represents the extension of the shelf life in 2 days. After this period the overripe odor starts to develop.

Color Changes of Tamarind (Tamarindus indica L.) Pulp During Fruit Development, Ripening, and Storage

Tamarind (Tamarindus indica L.) is a member of the dicotyledonous family Leguminosae. The fruit pulp has a pleasant acid taste and rich aroma, and thus, it is used as the chief souring agent for curries, sauces, and certain beverages. The unripe fruit pulp is green in color, while the ripe pulp is light brownish red. In storage, the brown pulp turns slowly to deep brown and finally black in color. In the present study, the cause of color changes during developmental stage, as well as during storage of tamarind pulp was investigated. Tamarind pulp in unripe condition (green pod) shows polyphenol oxidase activity up to 105 days of maturity of the fruit or until it ripens. Thereafter due to ripening there is a marked increase of reducing sugars and available lysine leading to Maillard reaction. This inhibits enzymatic browning in the ripe pulp during subsequent storage.

Use of Combinations of Commercially Relevant O2 and CO2 Partial Pressures to Evaluate the Sensitivity of Nine Highbush Blueberry Fruit Cultivars to Controlled Atmospheres

We tested the impact of storage atmospheres in which the CO2 and O2 percentages sum to 21% on highbush blueberry (Vaccinium corymbosum L.) fruit condition and quality. The CO2 and O2 combinations, in percent composition, were 19%/2%, 18%/3%, 16.5%/4.5%, 15%/6%, 13.5%/7.5%, 12%/9%, 6%/15%, and 0%/21% for CO2/O2, respectively. Nine blueberry cultivars were evaluated (Duke, Toro, Brigitta, Ozarkblue, Nelson, Liberty, Elliott, Legacy, and Jersey) after 8 weeks of controlled atmosphere (CA) storage at 0 °C. Surface mold, berry decay, skin reddening (associated with fruit pulp browning), fruit firmness, pulp discoloration, and the content of ethanol and acetaldehyde were assessed. Fruit firmness, skin reddening, and decay declined and the proportion of fruit with severe internal discoloration tended to increase as CO2 concentrations increased. Ethanol and acetaldehyde accumulation was minimal, indicating fermentation was not induced by the atmospheric conditions applied. Cultivar effects were far more pronounced than atmosphere effects. Some cultivars such as Duke, Toro, Brigitta, Liberty, and Legacy appear to be well suited to extended CA storage, whereas other cultivars such as Elliott stored moderately well, and Ozarkblue, Nelson, and Jersey stored poorly. The data indicate that responses to high levels of CO2, while O2 is maintained at its maximum level practicable, can, in a cultivar-dependent manner, include significant negative effects on quality while achieving the desired suppression of decay.