The physicochemical characteristics of new cultivars of Asian pears and anti-browning effect of ascorbic acid (AA) and sodium metabisulfite (SMS) in pear juice were investigated. First, the physicochemical characteristics of new cultivars of Asian pears were investigated. The moisture content of pea...
The physicochemical characteristics of new cultivars of Asian pears and anti-browning effect of ascorbic acid (AA) and sodium metabisulfite (SMS) in pear juice were investigated. First, the physicochemical characteristics of new cultivars of Asian pears were investigated. The moisture content of pears from new cultivars (Mansu, Yeongsan and Sinhwa) was ranged 84.52 to 86.24%. The pH, soluble solid content and titratable acidity of Mansu, Yeongsan and Sinhwa were ranged 4.80 to 5.68, 12.45 to 13.90 ˚Brix and 0.035 to 0.14%. In the color, flesh and peel of Mansu were the highest in L* value at 76.69 and 58.60, while flesh of Yeongsan and peel of Sinhwa were the highest in a* value at -0.63 and 11.25 and the lowest in b* value at 5.29 and 46.10 compared to other samples. In dietary fiber content, Mansu, Yeongsan and Sinhwa were 1.38 to 2.85% and 2.88 to 3.67% in soluble dietary fiber of flesh and peel, insoluble dietary fiber content of peel and flesh of Mansu, Yeongsan and Sinhwa was ranged 7.93 to 8.95% and 0.99 to 1.18%. However, it showed no significant difference in flesh of pears from 3 different cultivars. In free sugar content, flesh of Yeongsan has the highest value in fructose and galactose content, while flesh of Mansu and Sinhwa has the highest value in sucrose and glucose content at 465.52 and 638.00 mg/100 g. Potassium was major mineral in the flesh of Yeongsan, Mansu and Sinhwa. The content of minor minerals, such as calcium, magnesium, sodium and phosphorus were 3.46 mg/100 g, 7.36 mg/100 g, 2.03 mg/100 g, and 1.01 mg/100 g, respectively. Second, browning reduction and antioxidant activity of the pear juices added with different AA concentrations during storage for 12 and 24 hours at 37°C were investigated. Polyphenol oxidase (PPO) activities of pear juices added with 0.16, 0.20, and 0.24% AA concentration showed inhibition of 56.5, 78.8, and 77.9%, respectively. The pH of pear juices was 4.61 to 5.59, titratable acidity was ranged 0.04 to 0.16 in all samples including treatment in added with different AA concentrations during storage for 12 and 24 hours at 37°C. There was no significant difference in soluble solid content. The pear juices added with 0.20% and 0.24% AA concentration have higher L* value than control (no addition of AA) and juice with 0.16% AA concentration. Browning index of pear juices added with AA content was lower than that of control and increased during storage for 12 and 24 hours at 37°C. Vitamin C, DPPH radical-scavenging activity, reducing power and nitrite scavenging activity of all pear juices added with AA concentration were higher than that of control and decreased during storage for 12 and 24 hours at 37°C. Third, the application of SMS to inhibit both enzymatic browning and non-enzymatic browning in pear juices during processing and storage were also investigated. 80, 100, and 120 ppm of SMS inhibited 60.40, 81.50 and 82.1% of the PPO activity in the pear juices. The L* value of pear juices added with 100 ppm of SMS was higher than that of control (no addition of SMS) and of pear juices with 80 ppm of SMS during storage for 24 hours at 37°C. Browning index of pear juices added with SMS was lower than that of control, and there was increase during storage. During sterilization for 30, 40, and 50 min at 95°C, L* value of pear juices added with SMS was higher than that of control, and a* and b* value of control was higher than that of pear juices added with SMS. The Sulfite residual concentrations of pear juices added with 80 and 100 ppm were 3.31 and 8.18 ppm during sterilization for 40 min at 95°C. These values were lower than 10 ppm and it showed not detected level. During storage for sterilization pear juices at 45°C, ΔL value of pear juices added with 100 ppm of SMS was significantly lower than that of the control.
In conclusion, the physicochemical characterization of the new pear cultivars is worth noting for further processing. Additionally, concentration of 0.20% AA showed the best result in browning reduction for pear juice and pear juices added with 100 ppm of SMS could inhibit both enzymatic and non-enzymatic browning formation during processing and storage.
The physicochemical characteristics of new cultivars of Asian pears and anti-browning effect of ascorbic acid (AA) and sodium metabisulfite (SMS) in pear juice were investigated. First, the physicochemical characteristics of new cultivars of Asian pears were investigated. The moisture content of pears from new cultivars (Mansu, Yeongsan and Sinhwa) was ranged 84.52 to 86.24%. The pH, soluble solid content and titratable acidity of Mansu, Yeongsan and Sinhwa were ranged 4.80 to 5.68, 12.45 to 13.90 ˚Brix and 0.035 to 0.14%. In the color, flesh and peel of Mansu were the highest in L* value at 76.69 and 58.60, while flesh of Yeongsan and peel of Sinhwa were the highest in a* value at -0.63 and 11.25 and the lowest in b* value at 5.29 and 46.10 compared to other samples. In dietary fiber content, Mansu, Yeongsan and Sinhwa were 1.38 to 2.85% and 2.88 to 3.67% in soluble dietary fiber of flesh and peel, insoluble dietary fiber content of peel and flesh of Mansu, Yeongsan and Sinhwa was ranged 7.93 to 8.95% and 0.99 to 1.18%. However, it showed no significant difference in flesh of pears from 3 different cultivars. In free sugar content, flesh of Yeongsan has the highest value in fructose and galactose content, while flesh of Mansu and Sinhwa has the highest value in sucrose and glucose content at 465.52 and 638.00 mg/100 g. Potassium was major mineral in the flesh of Yeongsan, Mansu and Sinhwa. The content of minor minerals, such as calcium, magnesium, sodium and phosphorus were 3.46 mg/100 g, 7.36 mg/100 g, 2.03 mg/100 g, and 1.01 mg/100 g, respectively. Second, browning reduction and antioxidant activity of the pear juices added with different AA concentrations during storage for 12 and 24 hours at 37°C were investigated. Polyphenol oxidase (PPO) activities of pear juices added with 0.16, 0.20, and 0.24% AA concentration showed inhibition of 56.5, 78.8, and 77.9%, respectively. The pH of pear juices was 4.61 to 5.59, titratable acidity was ranged 0.04 to 0.16 in all samples including treatment in added with different AA concentrations during storage for 12 and 24 hours at 37°C. There was no significant difference in soluble solid content. The pear juices added with 0.20% and 0.24% AA concentration have higher L* value than control (no addition of AA) and juice with 0.16% AA concentration. Browning index of pear juices added with AA content was lower than that of control and increased during storage for 12 and 24 hours at 37°C. Vitamin C, DPPH radical-scavenging activity, reducing power and nitrite scavenging activity of all pear juices added with AA concentration were higher than that of control and decreased during storage for 12 and 24 hours at 37°C. Third, the application of SMS to inhibit both enzymatic browning and non-enzymatic browning in pear juices during processing and storage were also investigated. 80, 100, and 120 ppm of SMS inhibited 60.40, 81.50 and 82.1% of the PPO activity in the pear juices. The L* value of pear juices added with 100 ppm of SMS was higher than that of control (no addition of SMS) and of pear juices with 80 ppm of SMS during storage for 24 hours at 37°C. Browning index of pear juices added with SMS was lower than that of control, and there was increase during storage. During sterilization for 30, 40, and 50 min at 95°C, L* value of pear juices added with SMS was higher than that of control, and a* and b* value of control was higher than that of pear juices added with SMS. The Sulfite residual concentrations of pear juices added with 80 and 100 ppm were 3.31 and 8.18 ppm during sterilization for 40 min at 95°C. These values were lower than 10 ppm and it showed not detected level. During storage for sterilization pear juices at 45°C, ΔL value of pear juices added with 100 ppm of SMS was significantly lower than that of the control.
In conclusion, the physicochemical characterization of the new pear cultivars is worth noting for further processing. Additionally, concentration of 0.20% AA showed the best result in browning reduction for pear juice and pear juices added with 100 ppm of SMS could inhibit both enzymatic and non-enzymatic browning formation during processing and storage.
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#Asian pear new cultivar browning ascorbic aid sodium metabisulfite
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