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Volume 12, Issue 47 (7-2015)
Abstract

Iran is one of the most important fig producer countries around the world. Intermediate moisture fig is a processed product. One problem about intermediate moisture fig is that the color will be changed and transmute to brown during storage after processing. The purpose of this research was to study soaking temperature and time effects and to evaluate the effects of calcium chloride, cysteine, sodium metabisulphite and citric acid in various concentrations on prevention of semi-moisture fig browning at room temperature. Chemical compounds (protein, total sugar, fat, fiber and moisture) of fig samples were determined. In order to prepare product five different periods of time(3, 6, 9, 12, 15 min) and five different degrees of temperature (20, 40, 60, 80, 100°C) based on central composite rotational design were used. Samples were kept in room temperature for 2 weeks to evaluate the effects of soaking parameters on color and texture of product. After that moisture, color and texture of samples were determined. First different solution of calcium chloride (0.6, 1, 1.5, 2% w/w), citric acid (0.5, 1, 2, 3%w/w), cysteine (0.05, 0.07, 0.2, 0.5%w/w) and sodium metabisulphite (500, 800, 1000 and 1200 ppm ) were prepared. Dried figs were dipped in prepared solutions and water was used to evaluate control samples to optimize the time and temperature, then color of the samples were measured in specific period of time during four months. Results showed that temperature of 60°C and 3min interval provided 20% moisture in the product which assessed as the best moisture content for preserving color and texture. The most desirable L value was obtained using citric acid (1, 2, 3%w/w) and Calcium chloride (1.5%w/w). However sodium metabisulphite and cysteine in concentration of 0.07%, 0.05%, 0.2% showed significant difference with control, the results were not satisfactory. Results showed that using suitable temperature in rehydration of fig to inactivate poly phenol oxidase and chemical treatments to postpone and reduce the browning reaction rate were effective.    

Volume 12, Issue 48 (9-2015)
Abstract

There is not enough information about postharvest physiological behavior and optimum storage temperature of cultivated persimmons in Karaj region of Iran. In this study, persimmon fruit, cv. Karaj, was harvested at mature stage and was treated with hot waters at 45 and 50°C for 20, 30 and 45 min. Besides, one lot of fruit was bathed at 25°C for 30 min as control treatment. The physiological behaviors of treated fruits were monitored during 4 months storage at 0, 2 and 5°C. Results showed that severity of symptoms, such as; skin browning index, fruit softening, fungal disease incidence and loss of color indices (L*, a*, b*), were higher in storage at 2 and 5°C than storage at 0°C. Therefore, ʻKarajʼ persimmon was tolerant to 0°C for storing purpose. On the other hand, hot water treatments at 45°C for 30 and 45 min and 50°C for 20 min maintained fruit firmness and color properties, and controlled disease incidence better than that of control and hot water treatment at 45°C for 20 min. However, hot water treatment at 50°C for 30 and 45 min, in spite of maintaining suitable colour properties, contrary with other effective treatments caused to fruit skin browning and had notociable fungal disease. Therefore, hot water treatments at 45°C for 30 and 45 min and 50°C for 20 min are the recommendable treatments for increasing postharvest life of Karaj persimmon.  

Volume 14, Issue 64 (6-2016)
Abstract

The postharvest life of bottom mushroom is limited due to bacterial attack and enzymatic browning. This study was carried out in order to increasing the storability of mushroom, by antibacterial and anti-browning components. For that, the mushrooms were treated by oxalic and citric acids at concentration of 1.5 and 2.5 mM, hydrogen peroxide at concentration of 1 and 2.5%, ascorbic acid at concentration of 1.5 mM and calcium chloride at concentration of 1% as dipping for 2 min, and then treated mushrooms were packed in cellophane and stored at 4°C. Weight loss, marketability, electro leakage (EL) and bacterial colony forming unit (CFU) were measured after 8 and 16 days. According to the results, calcium chloride, ascorbic acid and hydrogen peroxide controlled browning as compared to control. However, oxalic and citric acids, despite reducing microbial load, did not show any positive effects. Calcium chloride by reducing weight loss, reducing EL and reducing bacterial load, ascorbic acid by reducing EL and reducing bacterial load and peroxide hydrogen by reducing bacterial load tended to increase postharvest life of bottom mushroom.

Volume 15, Issue 77 (9-2018)
Abstract

Mushrooms have low stability and therefore, use of applied scientific methods to increasing their stability has more important role to increasing product development. In order to study effect of nitric oxide treatment and maintenance time on physicochemical properties of mushroom (Agaricus bisporus) . A factorial experiment using completely randomized design with two concentrations of nitric oxide (0 & 4.5 mM) & 3 replication . In first time, two concentrations : 0 & 4.5 mM SNP (sodium nitroprusside) were prepared and mushrooms were dipped for 10 minutes in the solutions of nitric oxide donor, then packed in polystyrene bags, and stored at 4 ° C for 9 days, and mushroom properties were measured such as: firmness, total phenolics, ascorbic acid rate & activities of polyphenol oxidase in the days of 3, 6 and 9. The treatment of mushroom with nitric oxide significantly maintained quality at the end of the storage , So that mushrooms that containing 4.5 mM concentration nitric oxide compared with control and showed a high level of firmness, , maintained, Total phenol , ascorbic acid and reduce on activities of polyphenol oxidase on the third day in the storage. The results indicated that, the application of nitric oxide may be used as an effective and successful strategy to increase the shelf life of mushroom (Agaricus bisporus) .

Volume 15, Issue 83 (12-2018)
Abstract

Strong interest of consumers in acquiring minimally processed foods that conserve the different micronutrients has raised the need to study the effect of food processing methods on quality attributes. The aim of this study was to determine the effect ultrasound treatment (for 5, 10, 15 min at 37 and 80 kHz frequency) on physico chemical properties (titratable acidity, pH, oBrix, browning index, opacity), color attributes and microbial load (total microbial population, yeast and mold, and coliforms) of orange juice. Results showed non-significant changes for titratable acidity, °Brix, and pH in sonicated samples compared to control (p>0.05). The difference between browning and opacity indexes of the sonicated samples and heating treatment sample was significant (p<0.05) and the sonication caused to decrease the browning and opacity indexes of orange juices. The color parameters investigation of orange juice samples showed that the decreasing of frequency sonication and increasing the time of treatment leads to increase the lightness (L*), and decrease of the redness (a*) of orange juice samples. Significant reductions in the microbial load corresponding to sonication time were also recorded (p<0.05). Results of the present study indicate that sonication coupled with mild temperatures may be employed as a suitable technique for orange juice processing, and may be applied to improve its safety, sensorial and nutritional quality.
S. H. Mirdehghan, F. Ghotbi,
Volume 16, Issue 1 (1-2014)
Abstract

The pomegranate fruits of cvs. Malas Yazdi and Malas Ashkezar were immersed in SA (1 and 2 mM from source of acytyl salicylic acid) for five minutes, in JA (0.3 and 0.4 mM from source of n-propyl dihydrojasmonate) for fifteen minutes, in CaCl2 (1 and 2%) for five minutes, and in distilled water for five minutes as control. Then, the fruits were stored in cold storage at 1.5±0.5ºC and 85±5% relative humidity for 2 months. Every 21 days, samples were taken out of the cold storage and were kept at 20ºC for 3 days before analysis. The analysis results revealed that treatments with SA, JA, and CaCl2 significantly reduced the chilling injury of pomegranate fruits. The lowest chilling injury index was observed in 0.4 mM of JA-treated fruits and the highest was for untreated fruits. Electrolyte leakage of fruits increased upon treatments of fruits with 0.3 mM JA and 2 mM SA, but it was not significantly affected by other treatments. Treatments of fruits with SA, JA, and CaCl2 had no significant effect on phenolic compounds, but the total soluble solids of fruit juices was increased. Our findings indicated that total antioxidant activity decreased in treatments with 1, 2 mM SA and 0.3 mM JA , but it was not significantly affected by other treatments.

Volume 16, Issue 97 (2-2020)
Abstract

To study the effect of non-enzymatic browning reactions, quantification of 5-hydroxymethyl furfural (HMF) and on the browning index (BI) was done. In this study, the kinetics of BI in Sardasht black grape (Rasheh variety) juice concentrate was studied. Samples with different Brix's (60.5, 65.6 and 70.7) in three temperatures (5°C, 15°C, and 25°C) were kept for 85 days. In addition, the color analysis was also evaluated by a Hunter lab. Analysis of variance showed that all three factors (Brix, storage time and temperature) were effective in HMF content (P<0.05). They had a linear positive relation with HMF content in black grape juice concentrate. HMF content of concentrate was in the range of 0.57-50.6 (mg/kg). Also, all three factors had a significant effect on the BI (P<0.05) and its content was measured between1.054 - 1.373.

Volume 17, Issue 101 (5-2020)
Abstract

Drying due to the adverse physical and chemical changes is one of the most difficult processes in the food industry, especially to produce garlic powder. In this study, in order to avoid the Maillard reaction, garlics were pretreated by 0.5% sodium metabisulfite, 10% NaCl and citric acid (up to pH = 4) solutions. For this purpose, first, fresh garlic, after preparation according to the usual industrial method, was immersed in the pretreatment solution for 2 minutes at room temperature. The treated garlic was dried using cabinet method at 80 °C and 90 °C to achieve 5.2% water content, and then stored for 60 days at room temperature to evaluation of some quality characteristics including moisture content, vitamin C content, browning level, flavonoid content and pH. Based on the obtained results, moisture content did not change significantly in all treatments during storage. Control sample (without pretreatment) had had the highest off color and browning. Flavonoid and vitamin C contents were reduced in pretreated samples due to their solubility in water. Generally, based on the obtained results, garlic powder produced by pretreatments had lighter color than control sample which could increase their market acceptance and pretreatment with salt had highest effect in the production of garlic powder with a suitable color.  
 


Volume 17, Issue 109 (3-2021)
Abstract

Oxalic acid (OA), as a natural antioxidant, delays the ripening and senescence of fruits. In this research, the effect of different concentration of OA (0, 2, 4, 6, and 8 mM) investigated on storage life and postharvest quality of loquat fruit at 5°C and 90±5% relative humidity for 28 days. Traits such as browning index, biochemical and qualitative characteristics and activity of polyphenol oxidase (PPO) and peroxidase (POD) enzymes of fruit at harvest (0), 7, 14, 21 and 28 days after storage were analyzed. With increasing storage time, the level of browning index, total soluble solids (TSS), ratio of TSS/titratable acidity (TA) and the activity of PPO and POD enzymes increased in all treatments, while firmness, ascorbic acid, total phenol and flavonoids content and antioxidant activity decreased (p˂0.05). OA application significantly reduced the level of browning index and the activity of enzymes responsible for tissue browning (PPO and POD) compared to control (p˂0.05). At the end of storage, fruits treated with different concentration of OA had a more firmness tissue and higher level of ascorbic acid, total phenol and flavonoids content and antioxidant activity in comparison to the control fruits (p˂0.05). Overall, OA application effectively reduced fruit softening and browning index with diminished the activity of PPO and POD enzymes during cold storage. Thus, OA treatment (6 mM) can be used as an effective method for cold storage of loquat fruit.


Volume 18, Issue 119 (12-2021)
Abstract

Apple is one of the most valuable fruits which is produced and consumed throughout Iran. Fruit processing especially production of dried slices can be considered as a way to increase the value of apples and to prevent wastes. Producing apple slices with proper color and texture has always been one of the goals of producers in this field. In recent years, use of plant extracts has been the interest of many researchers in order to increase the shelf-life of agricultural products. In this study, the effect of grape pomace extracts (0، 100، 200، 300 and 400 ppm) on the phenolic content, antioxidant activity and color of apple slices dried at 47°C in Industrial dryer, 50°C and 60°C in oven were investigated. The results showed, the highest DPPH radical scavenging activity (85.97%), Fe reducing power (1.87 absorbance at wavelength of 700 nm) and phenolic content (245/87 mg of gallic acid equivalents in 100 g of dry matter) were achieved using 400 ppm concentration of grape pomace extracts. Also, the highest sensory score of dried apple slices were achieved at 300 ppm concentration of grape pomace extracts. In general, the results of this study indicated that the effect of Grape pomace extracts on the quality of apple dried slices was significantly positive. Concentration of 300 ppm of grape pulp extract has positive effect on the amount of phenolic complex and antioxidant properties of apple slices and its does not affect its taste.
H. Mortezapour, S. J. Rashedi, H. R. Akhavan, H. Maghsoudi,
Volume 19, Issue 6 (11-2017)
Abstract

In hot air dryers, only a small percentage of the provided thermal energy is used for the drying process, while a large fraction is lost via the exhaust air. To recycle waste heat from the exhaust air, the present study aimed to develop a solar dryer equipped with a novel heat recovery system. The designed dryer comprised of a solar air collector, a drying chamber, an internal closed-loop air circuit and an open-duct heat recovery system. The evaluation tests were conducted at different allowable relative humidities (RH) and mass flow rates of the recirculating air. The results indicated that the best solar fraction was at the highest RH and air flow rate. Increasing the RH from 7 to 17% caused a reduction of 51% in electricity consumption. Furthermore, electrical energy needed for drying increased by 24% with raising the air flow rate from 0.008 to 0.016 kg s-1. A minimum specific energy consumption of 7.54 MJ kg-1 was observed at the highest RH and the lowest air flow rate. At a constant RH, reduction of the air flow rate led to an increasing trend in lightness and decreasing trends in browning index of the products. Moreover, increasing the RH from 7 to 17% increased lightness and decreased browning index. In general, it can be stated that the best colour quality was achieved when the minimum air flow rate and the maximum RH were used for the solar drying.

Volume 19, Issue 124 (5-2022)
Abstract

This study was aimed to investigate the effect of Maillard reaction browning intensity (BI) on the interfacial properties of emulsion systems stabilized by soy protein isolate. The covalent bonding between soy protein isolate and gellan gum was confirmed by the BI and then the resulting protein-polysaccharide conjugates were classified into three low, medium, and high BI clusters using Hierarchical Agglomerative Clustering (HAC) method. Next, the emulsification properties (emulsifying capacity, emulsion stability, and the percentage of adsorbed protein), thermal stability, and rheological behavior of emulsion systems stabilized by the above clusters were evaluated. The emulsifying capacity and emulsion stability were increased more efficiently by the high BI soy protein isolate-gellan conjugate, showing its faster migration and absorption rate, and consequently higher percentage of absorbed protein to the interface, and also form a thicker, cohesive, and viscoelastic interfacial layer along with more steric repulsion at its oil/water interface. In addition, the apparent viscosity of emulsions in the presence of high BI conjugate was significantly higher than the systems stabilized by other conjugates (p<0.05). However, due to the more unmasked hydrophobic patches of the high BI conjugated protein, the thermal stability of its emulsion was lower compared to other counterparts. Therefore, the Maillard reaction under mild and controlled conditions along with minimal final compounds formation can improve the interfacial properties of soy protein to improve its application in the food industry.  

Volume 19, Issue 128 (10-2022)
Abstract

The purpose of clarification pomegranate juice by ultrafiltration process was its effect on bioactive compounds and degradation of bio-colorants during processing. For this aim, the effect of temperatures (20 and 30°C) and pressures (1.5, 2 and 2.5 bar) on anthocyanin, phenol, tannin and color indices were investigated. The results showed that the applied treatments significantly reduced anthocyanin in pomegranate juice. Treatments of 20°C-2 bar and 30°C-2 bar with 2.8 and 14.34% had the lowest and highest decrease in anthocyanin content, respectively. All treatments applied significantly reduced the total phenol content of pomegranate juice by 15-28-27%. Treatments of 20°C-2 bar and 30°C-2 bar with 6563.6 and 5696.9 mg/L had the highest and lowest phenols, respectively. The total tannin content for 20ºC and 30°C was 700.6 and 746.7 mg/L, respectively. The rate of reduction was between 39.34% for 1.5 bar-30°C treatment and 49.7% for 2.5 bar-20°C treatment. The total color density at 20°C and 30ºC was 1.09 and 1.17, respectively. Due to the rapid degradation of anthocyanins and tannins at high temperatures and generation of dark brown pigments, the total color density increased. The rate of tannin color reduction was between 39.34% for 1.5 bar-30°C treatment and 49.7% for 2.5-bar-20°C treatment. It was concluded that the effect of membrane process on tannin color reduction (45%) was more than anthocyanin color (23%). Regarding the browning index of permeation, the highest and lowest decreases equal to 34.45 and 19.88% were related to 2.5 bar-20°C and 2 bar-30°C, respectively.

Volume 19, Issue 131 (12-2022)
Abstract

In order to investigate the effect of GABA postharvest treatment on storage life and nutritional quality of fresh cut button mushroom, mushrooms treatment with five concentrations (0, 0.01, 0.1, 1 and 10 mM) of GABA done, and stored in the refrigerator for 15 days at a temperature of 4 °C and a relative humidity of 90±5 %, and the mushroom were sampled on days 0, 5, 10 and 15. The results showed that the concentration of 1 mM GABA had a greater effect on reducing the browning index of fresh cut button mushrooms than other concentrations of GABA. Reduction of electrolyte leakage and accumulation of malondialdehyde was observed in fresh cut mushrooms treated with a concentration of 1 mM GABA, which reduced weight loss in these mushrooms. High activity of phenylalanine ammonialyase enzyme in mushroom treated with 1 mM GABA increased the content of phenolic compounds which was associated with decreased activity of polyphenol oxidase enzyme. An increase in antioxidant capacity was observed in 1 mM GABA-treated mushrooms, which was accompanied by a significant increase in ascorbic acid accumulation in these mushrooms. Therefore, GABA as a safe and effective method can be used to increase the shelf life of fresh cut button mushrooms.

Volume 21, Issue 146 (3-2024)
Abstract

Ber fruit (Zizyphus mauritiana Lamk) contains abundant polyphenols and is highly susceptible to enzymatic browning after harvest. In order to reduce browning and maintain fruit quality of ber fruit, a factorial experiment was conducted in a completely randomized design with four replications. Experimental treatments included Aloe vera gel-based (20%) edible coating enriched with sesame oil 1%, honey 1% (ASH) and Zataria multiflora Boiss essential oil (ZEO) (0, 0.5 and 1%) and storage time (0, 7, 14, 21 and 28 days) at 6 ± 1°C and relative humidity of 90±5%. The results showed that edible coating application had significant effect on the quality characteristics of the ber fruit during storage. The combination of ASH with ZEO (0.5%), as an edible coating, significantly alleviated enzymatic browning by reducing PPO and POD activities on fruit during 28 days of storage. Fruits treated with ASH with ZEO (0.5%) reduced browning index (70%) compared to the control; while increased total phenol content and antioxidant activity (18.14%, and 31.16%, respectively) compared to the control after 28 days of storage. Also, ASH in combination with ZEO (0.5%) treatment decreased electrolyte leakage and malondialdehyde (19.7%, and 17.8%, respectively) compared to the control after 28 days of storage. These results indicated that ASH edible coating in combination with ZEO (0.5%) can be a useful method for delaying ripening and senescence, extending the storage life of ber fruit.
 

Volume 21, Issue 146 (3-2024)
Abstract

The aim of this work, was studying the effect of cold plasma treatment on enzymes and nutritional proteins denaturation, and ocurrance of browning reactions of bottled raw milk. A surface discharge plasma system was used for this purpose. The reactor of this system was a quartz cylinder with a diameter of 1 cm and a height of 25 cm. a steel cover with a thickness of 1 mm and height of 25 cm was used on the inner surface of the reactor and as a high voltage discharge electrode. The liquid inside the bottle (milk) was also considered as neutral electrode. The time of inactivation of catalase, alkaline phosphatase, lipase, peroxidase, and protease enzymes, bovine serum albumin, immunoglobulins, alpha lactalbumin, beta lactalbumin, lysine and thiamine were investigated. The simulation was performed by COMSOL a3.5 software for a two-dimensional geometry. The results showed the deactivation time of catalase, phosphatase, and lipase is highly low while the peroxidase and protease show the longest deactivation time. However the final deactivation time of all enzymes is highly low compared with thermal treatments. The peroxidase diactivated at 0.9 min and protease deactivated at 2 minutes after plasma treatment. The other enzyme deactivation time were 0.5 seconds. Also, the protein and amino acid denaturation time has a significant difference at p< 0.05. The inactivation time of lysine amino acid was shorter than other cases studies in this work, and beta-lactalbumin protein had the longest denaturation time. Also, the time of starting the browning reaction under plasma treatment was 3.4 minutes. It can be concluded that the studied cold plasma condition have no negative effect on proteins and color of milk.

Volume 21, Issue 150 (6-2024)
Abstract

The study was conducted exploit the proteins of the pods of some types of plants, such as Prosopis juliflora pods, that are considered by-products in many countries and considered a good source of protein in the preparation of protein hydrolysers and evaluating their effect on inhibiting brown discoloration of apple slices and compared with anti-browning agents (ascorbic acid, acetic acid, and sodium chloride) when stored in the refrigerator for 0, 5 and 8 days. The chemical composition of the moisture, protein, fat, ash, and carbohydrate of the P. juliflora pods was estimated, then the hydrolysis process was carried out using the enzymes trypsin and papain for 300 minutes. Amino acids and FTIR analysis of protein hydrolysates were determined. Significant changes (p≤0.05) in pH, total soluble solids, and non-significant changes in titration acidity of apple slices treated with protein hydrolysis and anti-browning agents were studied and significantly decreased (p≤0.05) in the activity of polyphenol oxidase until the end of the storage. The brown coloration decreased when treated with protein hydrolysates compared to other treatments, but non-significant changes. As a result, apple slices can be preserved with protein hydrolysers for several days in the refrigerator.
 

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