Pulp Browning Research Articles

Quality of minimally processed ‘Monalisa’ apples with antioxidants and edible toppings

Minimally processed fruits are an alternative to add value to products that are difficult to sell, in addition to facilitateconsumer consumption. The objective is to research pulp browning inhibition in a simulated commercialization of minimally processed ‘Monalisa’ apples, stored in a refrigerated environment. After being sanitized with sodium hypochlorite, the apples were cut and immersed in the following treatments: the control being sodium erythorbate (ES) + A (distilled water); ES + FM (cassava starch 3%); ES + AS (3% sodium alginate); ES + AM (6% waxy maize starch) and ES + AP (3% pine nut starch), all together with 1% calcium chloride. Afterwards, 10 slices were placed in a polyethylene tray, wrapped in stretchable PVC film and stored in a refrigerated chamber at 4 ºC ± 1 ºC and relative humidity of 90 - 95%. Phytochemical evaluations were performed at 0, 3, 6 and 9 days of storage. The applied treatments maintained fruit quality. The treatment with cassava starch and pine nut starch were efficient in preserving the darkening of the fruit pulp on day 9. As for the waxy corn starch treatment, the enzyme activity was lower in the period of 0 and 6 days, maintaining quality and delaying darkening. The control sample (ES + A + CC) stood out during the 9-day period, as there was a decrease in the activity of polyphenoloxidase and peroxidase enzymes.

Multiscale Static Compressive Damage Characteristics of Kiwifruit Based on the Finite Element Method.

In the handling or processing process, fruits are easily crushed by external loads. This type of damage in fruit often leads to the internal pulp browning and rotting, with the severity largely dependent on the fruit tissue's geometric and mechanical properties. In kiwifruits, with their thin skin and dark-colored flesh, it is particularly challenging to observe and analyze the damage caused by extrusion through traditional experimental methods. The objective of this research is to construct a multi-scale finite element model encompassing the skin, flesh, and core by measuring the geometric and mechanical properties of kiwifruit, to assess and predict the damage characteristics under compression, and to verify the accuracy of the finite element model through experiments. The results indicated that kiwifruits demonstrated different compressive strengths in different directions during compression. The compressive strength in the axial direction was higher than that in the radial direction, and there was little difference between the long and short radial directions. The flesh tissue is the most vulnerable to mechanical damage under external compression, followed by the core. At strain levels below 5%, there was no noticeable damage in the axial or radial directions of the kiwifruit. However, when strain exceeded 5%, damage began to manifest in some of the flesh tissue. To maintain fruit quality during storage and transportation, the stacking height should not exceed 77 fruits in the axial direction, 48 in the long direction, and 53 in the short direction. The finite element analysis showed that the established model can effectively simulate and predict the internal damage behavior of kiwifruits under compression loads, which is helpful for a deeper understanding of the mechanical properties of fruits and provides a theoretical basis and technical guidance for minimizing mechanical damage during fruit handling.

Synergistic improvement of antioxidant and antibacterial properties of carbon quantum complexes with zinc doping and chlorogenic acid for longan preservation

The deterioration of fruit could reduce the shelf life, decreased marketability and substantial economic value. Thus, a safe, simple, economical and environmentally friendly preservation technology for fruit is of great significance. Here, the postharvest preservation technology was investigated with zinc-doped carbon quantum dots and chlorogenic acid (Zn-CQDs/CGA) composite. Zn-CQDs/CGA composite were synthesized, which exhibits superior antioxidant and antibacterial activities. The binding mechanism of the Zn-CQDs/CGA composite was investigated, which revealed that the bindings of two components were mainly driven by hydrogen bonding and van der Waals forces to create a novel composite. The Zn-CQDs/CGA composite was applied to longan preservation and was found to significantly reduce the incidence of mildew spot, browning of fruit endocarp and pulp, as well as the degree of degradation of quality indexes. These results suggest that the Zn-CQDs/CGA composite has the potential for inhibiting browning and preserving the quality of longan during storage.

Kojic acid: evaluation of its effectiveness in controlling pulp browning in minimally processed ‘Royal Gala’ apples

Kojic acid: evaluation of its effectiveness in controlling pulp browning in minimally processed ‘Royal Gala’ apples

Effect of Mucilage-Based Edible Coating Enriched with Oregano Essential Oil on Postharvest Quality and Sensorial Attributes of Fresh-Cut Loquat

Due to pulp browning, weight loss, firmness loss, and decay, loquat fruits, and even more minimally processed fruits have a very short post-harvest life. The aim of our study was to evaluate the effect of Opuntia ficus-indica mucilage-based edible coating enriched with oregano oil on postharvest quality, microbial growth, and sensorial attributes of fresh-cut cv Martorana loquat fruit during cold storage. Fresh-cut loquat fruits were dipped in the mucilage-based solution enriched with oregano essential oil (MO-EC) and in distilled water used as control (CTR). According to our results, the mucilage-based edible coating enriched with oregano oil significantly improved the postharvest life of minimally processed loquat fruits by preserving quality, nutraceutical value, and sensory aspects. MO-EC had a barrier effect on fresh-cut loquat fruit, reducing weight and firmness losses, inhibiting TSS, TA, ascorbic acid content decrease, and enhancing the antioxidant activity until the end of the cold storage period (11 days at 5 °C). Microbiological analysis revealed that coated loquat fruits were characterized by a cell density of spoilage microorganisms 1 Log cycle lower than control fruits. The mucilage-based coating enriched with OEO positively affects the visual appearance of fresh-cut loquat fruits, at the end of the cold storage period, MO-EC samples did indeed report visual ratings that were five times greater than CTR samples. Our research suggests that applying mucilage-based coating enriched with OEO improves peeled loquat fruit shelf-life and allows the producers to sell products that are usually considered unmarketable (fruit with epicarp with large spot areas) to the market.

Glutamic acid can prevent the browning of fresh-cut potatoes by inhibiting PPO activity and regulating amino acid metabolism

Enzymatic browning during fresh cutting and storage affects the quality and commodity value of fresh-cut potatoes. The study investigated the effects of glutamic acid (Glu) on browning of fresh-cut potatoes. The results showed that Glu treatments significantly reduced the browning of potato pulp and shreds. Treated with the optimum concentration of 15 g/L Glu for 4 min prolonged the shelf-life of fresh-cut shredded potatoes to 5 d at 2–4 °C. Further research revealed that Glu treatment could inhibit the content of the total phenols, regulate the content of 16 free amino acids and repress the activity of polyphenol oxidase (PPO) via lowering pH value and chelating Cu2+. Molecular docking indicates that Glu stable bound to the active site of PPO. These results indicates that Glu treatment can inhibit the browning of fresh-cut potatoes by inhibiting PPO activity and the total phenolic content and regulating amino acid metabolism.

Mucilage-Based and Calcium Ascorbate Edible Coatings Improve Postharvest Quality and Storability of Minimally Processed Cactus Pear Fruit Stored under Passive Atmosphere

The minimally processed fruit and vegetable industry showed rapid growth worldwide, primarily due to the increasing consumer need for ready-to-eat fresh products characterized by high nutritional, sensory and healthy value. The postharvest life of peeled cactus pear fruits is relatively short, due to the processing operations that affect fruit integrity and cause metabolic disfunctions, as well as pulp browning, microbial growth, loss of firmness, off-flavor development, and nutraceutical value loss. In this study, we investigated the effects of mucilage-based (OFI) and calcium ascorbate edible coating on minimally processed cactus pear summer-ripening fruit, cold stored under passive atmosphere. The effect of the edible coating on the postharvest life, quality attributes, and nutraceutical value of fruit was evaluated by colors, total soluble solids content, carbohydrates; titratable acidity, ascorbic acid, betalains, DPPH, visual quality, and sensorial analysis. Our data showed a significant effect of mucilage-based and calcium ascorbate-based coating on preserving quality, nutritional value, sensorial parameters, and improving postharvest life of minimally processed cactus pear fruits; OFI had the most effective barrier effect. Furthermore, both coating treatments did not negatively affect the natural taste of minimally processed cactus pear fruits, which is an important aspect regarding the use of edible coatings when taste modification is undesirable.

Effect of Prolonged Cold Storage on the Dynamics of the Enzymatic and Non-Enzymatic Antioxidant System in the Mesocarp of Avocado (Persea americana) cv. Hass: Relationship with Oxidative Processes

This work evaluated the enzymatic and non-enzymatic antioxidant defense systems of avocados cv. Hass stored at 7 ± 0.5 °C for 10, 20, and 30 d, and at the stage of edible ripeness. The enzymatic antioxidant enzyme system included superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and the non-enzymatic antioxidant system was composed of total phenolic compounds (TPC), total carotenoids (TC), α-, β-, and γ-tocopherols, as well as hydrophilic (H-AOX) and lipophilic (L-AOX) antioxidant activities. In addition, polyphenol oxidase (PPO) and lipoxygenase (LOX) activities, TBARS values and pulp browning area were determined. At edible ripeness, low SOD and POD but higher CAT activities were evidenced in response to their joint participation in the oxidative stress developed. In addition, low content of γ-tocopherol and higher contents of TPC and TC were evidenced and suggest their individual or joint participation in defense against oxidation. The other compounds and activities evaluated tended to remain constant. Oxidative damage was evidenced by the increase in PPO activity and TBARS values, while LOX did not play a significant role. Pulp browning area did not surpass 6% in affected fruit. The results indicate that under these conditions oxidative stress was largely restrained by the endogenous fruit antioxidant defense system.

Postharvest Conservation of 'Thomson' Pitaya [Hylocereus undatus (Haw.) Britton and Rose] as a Function of Storage Temperature

Aims: The aim of this work was to evaluate the physico-chemical and biochemical attributes and the postharvest conservation of 'Thomson' [Hylocereus undatus (Haw.) Britton and Rose] under different storage temperature during storage.
 Study Design: The experimental design used was completely randomized with three treatments and four replications of four fruits/repetition.
 Place and Duration of Study: The experiment was carried out with 'Thomson' pitaya harvested in an organic orchard located in the municipality of São Miguel do Oeste, Santa Catarina, Brazil, during the 2018/2019 harvest.
 Methodology: The storage temperature treatments evaluated after postharvest were 23°C, 9°C and 4°C. The storage of the fruits was carried out in chambers with biochemical oxygen demand (BOD). The fruits were evaluated at different dates (7, 14, 21, 28 and 35 days) during storage.
 Results: At 7 days of storage, the fruits stored at 23 °C showed higher values ​​of mass loss, lipid peroxidation, pulp browning and activity of peroxidase (POX) and ascorbate peroxidase (APX) enzymes, as well as reductions in soluble solids contents (SS), titratable acidity (TA) and pulp firmness. At 14 and 21 days, storage at 9°C showed reductions in lipid peroxidation and pulp browning, as well as higher vitamin C contents and lighter and more intense skin color. Also, at 21 days, the fruits stored at 9°C showed higher values ​​of SS, AT and pulp firmness, and reductions in mass loss and in the activity of POX and APX enzymes.
 Conclusion: It is concluded that the storage of 'Thomson' pitayas at 23 °C provides a short postharvest period and early senescence of the fruits, while the temperature of 9 ºC increases the shelf life of the fruits and proves to be quite efficient in the conservation of the attributes of quality. The storage at 4°C is not recommended due to high internal browning, oxidative stress and loss of quality attributes.

Agronomic performance and fruit quality in greenhouse grown eggplant are interactively modulated by iodine dosage and grafting

Iodine (I) is considered an indispensable trace element for humans due to its capacity to promise a normal functions of thyroid hormones, preventing cretinism, goiter, reproductive failure, and diverse types of brain injury. Vegetable grafting is a technique for securing yield constancy and/or improving fruit quality. The study evaluated the combined effect of I-dosages and grafting onto Solanum torvum rootstock on ‘Birgah’ eggplant. Iodine at 100 or 300 mg L−1 enhanced marketable yield by 28.8% and 8.5%, respectively, compared with the control. Plants grafted onto S. torvum and self-grafted plants increased marketable yield by 53.0% and 45.8%, respectively compared with the ungrafted plants. I-biofortification determined a linear decrease in SSC as I-dosage increased. I-enrichment at 300 and 600 mg L−1 improved fruit dry matter and ascorbic acid compared with the control. The combinations of self-grafting × I-biofortification at 600 mg L−1 and ungrafting × I-biofortification at 600 mg L−1 improved total anthocyanins concentration by 8.5% and 9.1%, respectively, compared with the ungrafting × 0 I-biofortification combination. Exposing ungrafted plants to 600 mg I L−1 resulted in a significantly higher chlorogenic acid content compared to the control. Glycoalkaloids concentration in the fruits was always below the suggested safety value (200 mg 100 g−1 DW). Grafting enhanced proteins, K, Fe and Zn by 22.9%, 7.2%, 20.0% and 2.4%, respectively compared with ungrafting. I concentration in fruit of grafted plants varied from 0.67 mg kg−1 DW at 0 mg I L−1 to 188.67 mg kg−1 DW in plant biofortified with the highest I-dosage. The pulp browning potential was significantly dependent upon I-dosage and grafting with the lowest values found in fruits from grafted plants supplied with 0 or 100 mg I L−1. The present results suggested that I-biofortification at 300 or 600 mg L−1 and grafting, successfully boosted nutritional and functional traits of ‘Birgah’ eggplant, securing satisfactory yield and yield-related traits.

Eggplant grafting on a cold-tolerant rootstock reduces fruit chilling susceptibility and improves antioxidant stability during storage.

Vegetable grafting has been increasingly evaluated to improve preharvest tolerance to biotic and abiotic stresses. However, very few studies have identified rootstock-scion combinations able to improve fruit shelf life and reduce the susceptibility to postharvest disorders. Herein, a purple eggplant scion (cv. Monarca) was grafted onto a cold-tolerant hybrid Solanum rootstock ('Java') and the changes in growth, quality, postharvest chilling tolerance, and antioxidant stability were evaluated. Eggplant grafting enhanced plant vigor and fruit growth rate, decreasing the time from set to harvest by 10-15%. Grafted eggplants had a thinner shape and lighter pulp color than the control. The rootstock-scion combination tested showed lower respiration (~60%), dry matter (~15-20%), and phenolic compounds contents (~15-20%) than eggplants from non-grafted plants. Grafting markedly improved fruit performance during postharvest storage. Remarkably, grafted eggplants showed much higher tolerance to chilling injury than the control did, evidenced by a reduction of surface scalds along with decreased softening and pulp browning. The trend in antioxidants found at harvest time was reversed after cold storage due to enhanced stability (20% and 100% for pulp and peel respectively) in fruit from grafted plants. Purple eggplant (cv. Monarca) grafting onto 'Java' hybrid rootstock modulated fruit growth, quality at harvest, and increased fruit chilling injury tolerance during storage. Grafting may be a bona fide strategy to induce phenotypic traits able to improve vegetable postharvest performance. © 2021 Society of Chemical Industry.

Investigation and Evaluation of Impact Bruising in Guava Using Image Processing and Response Surface Methodology

Simulated impact damage testing was investigated by fractal image analysis using response surface methodology (RSM) with a central composite design (CCF) on quality of ‘Glom Sali’ guava for drop heights (0.2, 0.4, and 0.6 m), number of drops (1, 3, and 5) and storage temperature conditions (10, 20, and 30 °C). After 48 h, impacted fruit were determined and analyzed for bruise area (BA), bruise volume (BV), browning index (BI), total color difference (∆E), image analysis for bruise area (BAI), and fractal dimension (FD) at the bruising region on peeled guava. Results showed that the correlation coefficient (r = −0.6055) between ∆E and FD value was higher than ∆E and either BA (r = 0.3132) or BV (r = 0.2095). The FD variable was determined as a better indicator than conventional measurement (BA or BV) for pulp browning and impact bruising susceptibility. The FD variable also exhibited highest R2adj value (81.69%) among the other five variables, as the highest precision model with high determination coefficient value (R2adj) (>0.8) for impact bruising prediction. Recommended condition of the FD variable to minimize impact bruising was drop height of 0.53 m for five drops under storage at 30 °C. FD variable assessed by image analysis was shown to be a highly capable measurement to determine impact bruising susceptibility in guava fruit.

The effects of drying temperature on the kinetics, color, structure, and pectin composition of Zizyphus jujuba Mill. cv. Junzao

Drying kinetics, color, and texture changes in different drying temperatures of jujubes were investigated in this study. With the increase of temperature, the drying time reached a minimum (140 min) at 80℃. At the temperature of 40℃, the retention of the original color was the greatest (ΔE = 1.66); similar results were also reflected by the measured pulp browning (4.186 ± 0.350 Abs/g) and 5-HMF (0.517 ± 0.044 mg/g). After drying, the fruit hardness decreased to 55.91%–86.59% of the initial (2,543.2 ± 181.4 g). SEM showed that the HAD temperature exceeded 60℃ and the pulp tissue sharp dramatically, causing the fruit to harden. Affected by drying temperature and polygalacturonase, WSP increased in drying, whereas CSP and NSP showed the opposite trend, and they were significantly correlated with the texture of fruits. The results expanded our understanding of the jujube drying process and provided guidance for controlling the quality of jujube during HAD processing. Practical applications The drying method of jujube fruit in China is special, which is a combination of air drying and hot air drying. However, discoloration, shrinkage, and other quality deterioration occurred during the drying process, significantly affecting the quality of jujube fruit. In this study, semi-air-dried jujubes were used to investigate the color and texture during hot air drying. These results will provide valuable information to the pilot or industrial scale processors and also served as an operational guide for the jujube fruit drying process.

Transcriptome profiling reveals potential genes involved in browning of fresh-cut eggplant (Solanum melongena L.)

Fresh-cut processing promotes enzymatic browning of fresh fruits and vegetables, which negatively affects the product appearance and impacts their nutrition. We used RNA-sequencing to analyze the transcriptomic changes occurring during the browning of fresh-cut eggplant fruit samples from both browning-sensitive and browning-resistant cultivars to investigate the molecular mechanisms involved in browning. A total of 8347 differentially expressed genes were identified, of which 62 genes were from six gene families (i.e., PPO, PAL, POD, CAT, APX, and GST) potentially associated with enzymatic browning. Furthermore, using qRT-PCR, we verified 231 differentially regulated transcription factors in fresh-cut eggplant fruits. The enzyme activities of PPO, POD, PAL, and CAT in ‘36’ were significantly higher than those of ‘F’ fresh-cut for 15 min. Both PPO and POD play a major role in the browning of eggplant pulp and might therefore act synergistically in the browning process. Meanwhile, qPCR results of 18 browning related genes randomly screened in 15 eggplant materials with different browning tolerance showed variant-specific expression of genes. Lastly, gene regulatory networks were constructed to identify the browning-related genes. This work provides a basis for future molecular studies of eggplants, and lays a theoretical foundation for the development of browning-resistant fresh-cut fruits and vegetables.

24-Epibrassinolie Enhances the Effect of Calcium and Boron on Amelioration of Aril Browning Disorder in Pomegranate (Punica granatum cv. ‘Rabab’)

Aril browning is a serious physiological disorder especially under environmental stress in pomegranate (Punica granatum cv. ‘Rabab’). Evidence shows that calcium (Ca), boron (B), and brassinosteroids (BRs) could improve cellular protection, stimulates anthocyanin biosynthesis, and reduce pulp browning. In this experiment, the simple and interactive effect of 24-epibrassinolide (EBR) on increasing the efficiency of Ca and B on improving the aril browning disorder in ‘Rabab’ pomegranate was investigated. A factorial experiment was conducted in a randomized complete block design with the exogenous foliar spray of EBR at two levels − 0 (Ctrl.), and − 0.4 mg L−1 and foliar nutrition contained − untreated (Ctrl.), − calcium chelate (2 g L−1), − boric acid (0.5 g L−1) and − calcium chelates (2 g L−1) + boric acid (0.5 g L−1). The foliar spray was applied a week before full bloom, 4 weeks after full bloom, and before the arils fully mature stage. The interactive effect of EBR1 + Ca + B had the highest influence on the reduction of the browning index (BI). This treatment significantly increases fruit total soluble solids (TSS), total anthocyanin, phenolic, and flavonoid content that had a negative correlation with the BI in cv. ‘Rabab’ pomegranate. Exogenous foliar spray of EBR significantly enhanced the effect of Ca and B on reducing the aril browning disorder, and this effect could be due to the improving the pollen function and fruit quality indices, which plays a very important role in controlling synthesis and preventing dissociation of anthocyanin.

Influence of anti‐browning treatments on enzymatic browning, distinctive properties, and microbiological characteristics of banana pulp during short‐term frozen storage

Banana pulps (ripe and overripe) were taken to investigate the effectiveness of various anti-browning agents (0.1 and 0.2% potassium metabisulfite (KMS), 1 and 2% citric acid (CA), 1% ascorbic acid (AA), 1% CA + 0.5% L-cysteine, 1% CA + 0.5% CaCl2, 1% CA + 1% AA + 0.5% cysteine) to prevent enzymatic browning. Based on the polyphenol oxidase activity, color and sensory attributes, the most effective anti-browning agent was selected. Results showed that KMS at 0.1% was most effective in inhibiting the browning reaction, which was further used for evaluating the effect of frozen storage (−16°C) for 180 days along with control. But the control sample lasted for 30 days. In ripe pulp: TSS, total and reducing sugars increased, whereas in overripe it decreased during storage but, the pH remained stable. The ascorbic acid, carotenoids, phenols, and color value decreased for both samples slightly during freeze storage. Practical applications The response of enzymatic browning in banana pulp to different anti-browning agents is highly variable. In our findings, we found that potassium metabisulfite (KMS) is highly effective in inhibiting (100%) polyphenol oxidase activity. Further, banana pulp stored with KMS treatments showed a slight variation in physicochemical attributes during frozen storage (−16°C) for 180 days. The banana pulp seems to be an important food industrial application by increasing economic value along with waste reduction by minimize losses during postharvest. However, providing the producer an alternative use for converting pulp into various valuable products.

Road transport vibration stress impact on ‘Palmer’ mangoes quality and shelflife

Abstract Studying the causes of postharvest fruit loss is important to avoid reduction of quality and quantity for the consumer due, for example, to the influence of frequent impacts from vibrations during transportation. In this sense, this study evaluates the storage quality of ‘Palmer’ mangoes after being subjected to different simulated road transport vibrations. Vibration was simulated from the analysis of the profile of the frequencies generated in road transport of fruit, determined in a tractor trailer. ‘Palmer’ mangoes stored after vibration stress wereevaluated for: mass loss, absorbance difference index (IAD), peel and pulp browning index (BI), pulp firmness, soluble solids content, and titratable acidity. The development of a vibration machine made it possible to satisfactorily simulate specific vibration frequencies. Vibration stress during simulated transport led to accelerated weight loss, decreased pulp firmness, and peel browning in ‘Palmer’ mangoes.

A novel aspartic protease inhibitor inhibits the enzymatic browning of potatoes

• StASPI expressed highly in browning-less potato than in browning-susceptible potato. • Both exogenous Pepstatin A and overexpressed -StASPI inhibited potato browning. • Overexpressed StASPI reduced protease activity and contents of free amino acids. • Overexpressed StASPI decreased PPO activity. • Overexpressed StASPI enhanced SOD and CAT activity, and reduced ROS contents. Enzymatic browning greatly affects the quality of fresh-cut potatoes ( Solanum tuberosum L.). The transcript level of a novel aspartic protease inhibitor gene, StASPI , was found significantly higher in browning-less potatoes than in browning-susceptible potatoes, and exogenous aspartic protease inhibitor Pepstatin A inhibited the browning of potato pulp. Therefore, we speculated that StASPI plays important roles in browning-resistance of potatoes. The effects of overexpressed- StASPI on browning, total free amino acids (FAAs), antioxidant enzyme activity and ROS accumulation in potatoes were investigated in this study. Results showed that overexpression of StASPI effectively reduced enzymatic browning after cutting, significantly decreased protease activity, and reduced the accumulation of total FAAs in potatoes. Browning degrees of transgenic potato mash were increased by supplementing exogenous FAAs, but the degrees were still significantly lower than that of wild-type (WT) mash. Furthermore, overexpression of StASPI decreased PPO activity, enhanced the activities of antioxidant enzymes SOD and CAT, and reduced H 2 O 2 and O 2 ˙ ― contents. These results indicated that overexpression of StASPI inhibited the enzymatic browning of potatoes, decreasing FAAs accumulation, reducing PPO activity, and enhancing activity of antioxidant enzymes. This study provides a new perspective on the strategies for inhibiting enzymatic browning of potatoes.

Addition of preservatives to minimally processed ‘BRS Kampai’ peaches (Prunus persica L.)

Fruits that go through processes of sanitation, peeling, cutting and packaging, to be consumed soon afterwards, are called minimally processed fruits. Since fruit consumption is important in the human diet, consumers have looked for practicality in both preparation and consumption, a situation that includes minimally processed food. However, minimal processing can damage plant tissues, mainly by pulp browning and by accelerating changes in natural characteristics of the product. This study aimed at minimizing changes in minimally processed sliced peaches by immersing them in solutions which contained preservatives. The experiment was a completely randomized design in a 5x3 factorial scheme (5 anti-browning agents x 3 storage periods), with 4 trays per replicate and six slices of peaches in every replicate. Sliced fruits were treated with T1 = control (distilled water); T2 = ascorbic acid at 1% (m/v); T3 = sodium isoascorbate at 1% (m/v); T4 = ascorbic acid at 0.5% (m/v) + sodium isoascorbate at 0.5% (m/v); and T5 = citric acid at 0.5% (m/v) + sodium isoascorbate at 0.5% (m/v). Afterwards, they were placed on trays, covered with 9µ PVC film and stored at 4±1ºC for 0 (S1), 6 (S2) and 12 (S3) days. The following variables were evaluated: mass loss, pulp color, pulp firmness, soluble solids, titratable acidity, pH, rot spots, total phenols and antioxidant activity. The treatment that consisted of citric acid at 0.5% (m/v) + sodium isoascorbate at 0.5% (m/v) was the most efficient one to control oxidation; its values of browning indexes were the lowest ones, i. e., 15.62 (S1), 17.74 (S2) and 17.58 (S3). Besides, it kept the creamy-white color of the pulp throughout storage time.

Effect of 4-hexylresorcinol on post-cut browning and quality of minimally processed ‘Fuji’ apple fruits

Demand for minimally processed apples (MPA) is growing, as it is an easy-to-consume food rich in vitamins, minerals, fiber and phenolic compounds that benefit consumer health. However, MPA perishability is a hindrance in meeting this demand due to enzymatic browning of the pulp. To minimize this problem, the effectiveness of different concentrations (0.1%, 0.2% and 0.3%) of 4-hexylresorcinol (4-HR) were tested on MPA (sliced Fuji apples) for up to nine days at 4.0 °C. Distilled water (DW) and l-cysteine chloride (LC) 0.6% (m v− 1), were used as negative control and positive control, respectively. The color, mass loss, pulp firmness, bioactive compounds, enzymatic activity and sensorial characteristics were evaluated. After the evaluations, it was found that the different concentrations of 4-HR exerted undesirable effects on the color variables (L *, a *, oHue and browning index), because it did not effectively inhibit the browning of the apple pulp. During storage, fruits treated with 4-HR gradually lost weight without affecting quality; had greater firmness and their total phenolic content and antioxidant activity remained superior to controls (DW and LC). Although the activity of the peroxidase and polyphenol oxidase enzymes was decreased, the sensorial analysis revealed that dark spots formed in the endocarp, and also in the mesocarp, impairing the purchase intention of the MPA. Based on these considerations, immersion in 4-hexylresorcinol was considered not suitable for controlling pulp darkening of ‘Fuji’ apples minimally processed during refrigerated storage.