Protection of antioxidants in pitaya (Hylocereus undatus) peel: effects of blanching conditions on polyphenoloxidase, peroxidase and antioxidant activities
Abstract:Pitaya peel is a by-product of the fruit processing, rich in phytochemicals and has great potential for application in food industry. In this study, blanching was applied to the pitaya peel treatment for inactivation of the polyphenoloxidase (PPO) and peroxidase (POD) which caused the antioxidant loss in the material during the processing and preservation. The effects of blanching temperature and time on the PPO and POD activities as well as the stability of betacyanins and phenolics of pitaya peel were invest… Show more
“…But the grapes lose their texture at this duration. Similar findings were reported by Noreña and Rigon [48] and Mai et al [49] regarding the effect of blanching duration on PPO and POD inhibition. During blanching, the heat denatures the PPO and POD protein structures and deactivates the enzymes by disrupting the weak bonds that hold the enzyme molecules together, resulting in the loss of their catalytic activity [50].…”
Section: Effect Of Blanching Time On Ppo and Pod Residualsupporting
Drying is a common technique in the agrifood industry, but insufficient control in the drying process can result in changes to the fruit’s appearance due to physiological damage during processing. The aim of this study was to investigate the impact of pretreatment and drying process parameters on Moroccan raisins’ quality and safety. The experimental levels of pretreatment factors (blanching, browning agents) and drying temperature were defined at the beginning. Subsequently, a 24-factorial design was employed to provide a simple and reliable model capable of relating directly the response factor (drying time, color intensity change (
E
∗
), chromaticity (
C
∗
), and browning rate) to the variables (NaOH concentration, antibrowning agent concentration, temperature, and relative humidity). All four parameters had a statistically considerable effect on studied responses. Blanching for 5 minutes at 1% of NaOH solution, using an appropriate concentration of antibrowning agent (5% Na2S2O5), and drying at 70°C with 30% of relative moisture can lead to better preservation of grapes’ appearance and quality (chromaticity (
C
∗
) and color change (
E
∗
)). Also, in these conditions, a lower browning rate (14.48%), a lower 5-hydroxymethylfurfural content (12.40 mg/100 g DW), and a higher level of polyphenols (
135.79
±
13.17
mg GAE/100 g DW) and flavonoid content (
57.81
±
3.08
mg Qeq/100 g DW) have been recorded while meeting international standards for SO2 content and microbial quality.
“…But the grapes lose their texture at this duration. Similar findings were reported by Noreña and Rigon [48] and Mai et al [49] regarding the effect of blanching duration on PPO and POD inhibition. During blanching, the heat denatures the PPO and POD protein structures and deactivates the enzymes by disrupting the weak bonds that hold the enzyme molecules together, resulting in the loss of their catalytic activity [50].…”
Section: Effect Of Blanching Time On Ppo and Pod Residualsupporting
Drying is a common technique in the agrifood industry, but insufficient control in the drying process can result in changes to the fruit’s appearance due to physiological damage during processing. The aim of this study was to investigate the impact of pretreatment and drying process parameters on Moroccan raisins’ quality and safety. The experimental levels of pretreatment factors (blanching, browning agents) and drying temperature were defined at the beginning. Subsequently, a 24-factorial design was employed to provide a simple and reliable model capable of relating directly the response factor (drying time, color intensity change (
E
∗
), chromaticity (
C
∗
), and browning rate) to the variables (NaOH concentration, antibrowning agent concentration, temperature, and relative humidity). All four parameters had a statistically considerable effect on studied responses. Blanching for 5 minutes at 1% of NaOH solution, using an appropriate concentration of antibrowning agent (5% Na2S2O5), and drying at 70°C with 30% of relative moisture can lead to better preservation of grapes’ appearance and quality (chromaticity (
C
∗
) and color change (
E
∗
)). Also, in these conditions, a lower browning rate (14.48%), a lower 5-hydroxymethylfurfural content (12.40 mg/100 g DW), and a higher level of polyphenols (
135.79
±
13.17
mg GAE/100 g DW) and flavonoid content (
57.81
±
3.08
mg Qeq/100 g DW) have been recorded while meeting international standards for SO2 content and microbial quality.
“…Total carbohydrate content was calculated by subtracting the sum of protein, fat, and ash percentages from 100%. Betacyanin and total phenolic contents as well as DPPH inhibition activity and ferric reducing power were evaluated according to the procedure described by [21].…”
Pitaya fruit processing generates a large amount of pitaya peel which contains high level of dietary fiber, betacyanins and phenolic compounds. In this study, pitaya peel powder was added to cookie formulation and the ratio of pitaya peel powder was varied from 0 to 25% of the amount of wheat flour. The obtained cookie samples were then used for analysis of proximate composition, physical properties, overall acceptability, predicted glycemic index and antioxidant release during in vitro sequential digestion. The higher the ratio of pitaya peel powder in the recipe, the greater the dietary fiber, betacyanin and phenolic contents and antioxidant activities of the product. High pitaya peel ratio also resulted in enhanced hardness and increased intensity of red color of the cookies; however, all cookie samples were considered acceptable. The use of pitaya peel significantly reduced the glycemic index of cookies and all supplemented pitaya peel cookies were classified as having low glycemic index. The release of betacyanins, phenolics and antioxidant activities from the cookie samples was recorded at the salivary, gastric, intestinal and colon steps during in vitro sequential digestion and the gastric digestion showed the highest release of antioxidant content and activity. The increased pitaya peel ratio in the cookie recipe improved the antioxidant activities of the soluble fractions at the four digestive steps.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.