Polyphenol Oxidase Activity In Fruits Research Articles

Influence of plant growth substances on reproductive growth, yield and fruit quality of pear (<i>Pyrus communis</i> L.) cv. Punjab Beauty

Under sub-tropical region, poor fruit set is a major constraint in semi-soft pears resulting in lower fruit yield. To study the effect of plant growth substances on fruit production and quality, the plants of pear cv. Punjab Beauty were sprayed with the plant growth substances viz., boric acid (200, 300 ppm), CPPU (5, 10 ppm), NAA (10, 20 ppm) and P-Ca (150, 300 ppm) at full bloom stage. Among all the applied treatments, boric acid @ 200 ppm proved to be most effective with maximum fruit set (6.91 %), fruit retention (59.9 %) and yield (57.8 kg/plant), while, maximum fruit weight (162.3 g) was observed with NAA (20 ppm). The highest internal fruit quality in terms of maximum TSS (12.4o Brix), TSS/acid ratio (53.4) and ascorbic acid (12.8 mg kg-1) was observed in 200 ppm boric acid. However, the total phenol (30.9 mg GAE/100 pulp) and flavonoid (36.1 mg CE/100 pulp) content was significantly higher with NAA (20 ppm). The plant growth substances reduced the polyphenol oxidase activity in fruits. Overall, the application of boric acid (200 ppm) resulted in improved fruit set, yield and quality in pear cv. Punjab Beauty.

Influence of plant growth substances on reproductive growth, yield and fruit quality of pear (<i>Pyrus communis</i> L.) cv. Punjab Beauty

Under sub-tropical region, poor fruit set is a major constraint in semi-soft pears resulting in lower fruit yield. To study the effect of plant growth substances on fruit production and quality, the plants of pear cv. Punjab Beauty were sprayed with the plant growth substances viz., boric acid (200, 300 ppm), CPPU (5, 10 ppm), NAA (10, 20 ppm) and P-Ca (150, 300 ppm) at full bloom stage. Among all the applied treatments, boric acid @ 200 ppm proved to be most effective with maximum fruit set (6.91 %), fruit retention (59.9 %) and yield (57.8 kg/plant), while, maximum fruit weight (162.3 g) was observed with NAA (20 ppm). The highest internal fruit quality in terms of maximum TSS (12.4o Brix), TSS/acid ratio (53.4) and ascorbic acid (12.8 mg kg-1) was observed in 200 ppm boric acid. However, the total phenol (30.9 mg GAE/100 pulp) and flavonoid (36.1 mg CE/100 pulp) content was significantly higher with NAA (20 ppm). The plant growth substances reduced the polyphenol oxidase activity in fruits. Overall, the application of boric acid (200 ppm) resulted in improved fruit set, yield and quality in pear cv. Punjab Beauty.

Response of Black (Morus nigra), White and White Shahtoot (Morus alba) Mulberry Fruits to Ascorbic Acid Treatment and Drying Methods

The drying process plays an important role in heat-sensitive product dehydration. This study was conducted to evaluate the response of three species of mulberry fruit (Morus nigra L. (Black mulberry), Morus alba L. (White mulberry), and Morus alba L. (White shahtoot) grown in Halabja, Kurdistan region, Iraq. Four levels of ascorbic acid treatment at 0%, 10%, 20% and 30% lthen, divided into two groups; the first dried under solar radiation the second dried by one of the very high-quality machines (oven) for drying all kinds of vegetables and fruits. The mulberry fruits were harvested at the ripening stage by hand in April 2021 from the trees 10 years old. The results appeared that black mulberry is significantly superior that has higher moisture and total sugars content while having the lowest ash content and polyphenol oxidase activity on the two other species. Additionally, the ascorbic acid treatment significantly decreased total sugars content and peroxidase activity, while significantly increasing moisture content and polyphenol oxidase activity in fruits as compared to untreated fruits. Furthermore, sun drying significantly increased the fruits content of moisture, ash, total sugars, and polyphenol oxidase activity as compared to oven drying.

New Method for Accurate Determination of Polyphenol Oxidase Activity Based on Reduction in SERS Intensity of Catechol.

Rapid and accurate measurement of polyphenol oxidase (PPO) activity is important in the food industry as PPOs play a vital role in catalyzing enzymatic reactions. The aim of this study was to develop surface-enhanced Raman scattering (SERS) approach for accurate determination of PPO activity in fruit and vegetables using the reduction in SERS intensity of catechol in reaction medium. Within a certain catechol concentration, when a purified PPO solution was analyzed, the reduction in SERS intensity (Δ I) was linear to PPO activity ( Ec) in a wide range of 500-50 000 U/L, and a linear regression equation of log Δ I/Δ t = 0.6223 log Ec + 0.8072, with a correlation coefficient of 0.9689 and a limit of detection of 224.65 U/L, was obtained. The method was used for detecting PPO activity in apple and potato samples, and the results were compared with those obtained from colorimetric assay, which demonstrated that the proposed method could be successfully used for detecting PPO activity in food samples.

Enzymatic browning in avocado (Persea americana) revisited: History, advances, and future perspectives

ABSTRACTConsidering nearly 80 years of research regarding one of the enzymes responsible for catalyzing the formation of pigments in higher animals, plants, fungi and bacteria, this review will focus on collecting and categorizing the existing information about polyphenol oxidase (PPO) in fruits, with particular emphasis on the information in relation to avocado, which is one of the hardiest species in terms of inactivation, has documented dual activity (EC 1.14.18.1/EC 1.10.3.1), and represents one of the oldest challenges for food science research and fruit processors.It is expected that this review will contribute to the further development of the field by highlighting the questions that have arisen during the characterization of PPO, the progress that has been made and the questions that remain today, in addition to new methodologies that are being applied to study this system. Holistic methodologies offer unexplored potential for advancing our understanding of the complex phenomena that govern PPO activity in fruits, because these methodologies will enable the characterization of this family of enzymes in all of its complexity. Subsequently, it will be possible to develop better techniques for controlling enzymatic browning in this valuable fruit.

PURIFICATION AND CHARACTERIZATION OF POLYPHENOL OXIDASE FROM GOLDNUGGET LOQUAT (ERIOBOTRYA JAPONICA CV. GOLDNUGGET)

ABSTRACT Polyphenol oxidase (PPO) was extracted and purified from Goldnugget loquat and its characteristics were studied. Two protein peaks containing PPO activity were recovered, which were denoted as isoenzyme A and isoenzyme B. A 5.7-fold purification of isoenzyme A with a recovery of 15.3% and 61.1-fold purification of isoenzyme B with a recovery of 98.9% were achieved. Assay of activity of the isoenzymes between pH 3.04 and 7.80 using catechol as substrate showed two activity peaks, one at acidic pH and the other at neutral pH. pH optima of isoenzyme A and B were found to be at 4.5 and 6.8, respectively. Isoenzyme A exhibited a higher activity at acidic pHs than isoenzyme B. They both displayed maximal activity at 30C. Thermal resistance of isoenzyme A was found to be higher than that of isoenzyme B. Effect of inhibitors on the isoenzymes varied markedly. PRACTICAL APPLICATION Enzymatic browning catalyzed by polyphenol oxidase (PPO) is generally considered to be detrimental to food quality from both organoleptic and nutritional points of view. Polyphenol oxidase-catalyzed browning reactions in fruits and vegetables during handling and processing impairs the sensory properties and marketability of the product and also lowers the nutritional value. An understanding of the essential factors controlling the action of PPO is necessary in an attempt to inhibit or control PPO activity in fruit and vegetables during processing. Therefore, it is important to control the PPO activity, as well as to determine its characteristics associated with the variety.

The control of polyphenol oxidase activity in fruits and vegetables. A study of the interactions between the chemical compounds used and heat treatment.

Objective of this research was to find alternative methods for the control of polyphenol oxidase (PPO) activity in fruits and vegetables with the purpose of reducing or eliminating the use of SO2 for this purpose. Interactions between the use of ascorbic acid, citric acid, EDTA, sodium metabisulphite and heat treatment (70 degrees C for 2 min) in the control of PPO activity were studied in avocado (var. Fortuna), banana (var. Nanica), apple (var. Ana, Fuji, Gala & Golden), pear (var. D'Agua), peach (var. Réal), potato (var. Bintje), eggplant (var. Super F100), mushroom (Agaricus bisporus) and hearts-of-palm (Euterpe edulis Mart). The results demonstrated that PPO of avocado and eggplant was most resistant to inhibition by the methods used. The least efficient method tested for the control of PPO was the addition of ascorbic acid and EDTA, while the most efficient methods investigated included the use of ascorbic acid, citric acid, sodium metabisulphite and heat treatment. The results indicated that, with the exception of PPO from avocado, the most adequate alternative method to substitute for the use of SO2 in the control of PPO was a combination of ascorbic acid, citric acid and heat treatment.

The effect of stress history and container ventilation on avocado fruit polyphenol oxidase activity

SummaryMature cv Fuerte avocado fruits were picked from trees with and without a water stress history during early fruit development. The interaction between stress and restricted container ventilation, after storage at 5.5°C for 30 days, in relation to the fruit browning potential of soft fruit as evidenced by polyphenol oxidase (PPO) activity was investigated. Soluble PPO activity increased in fruit from stressed (infrequently irrigated) trees when ripened after being placed for 48 h in restricted ventilation. Fruit from moderately irrigated (non-stressed) trees showed no increase. Total PPO showed a similar but not significant trend. It is concluded that restricted ventilation causes a release of bound PPO. It is speculated that stress history predisposes fruit to membrane breakdown under restricted ventilation conditions, resulting in a higher browning potential for such fruit.