Analyze The Total Phenols And Related Enzymes’ Activity On Luffa Browning Classification

Luffa is one of the vegetables cultivated universally worldwide, and one of the main cucurbits extensively cultivated in domestic. At present, pulp browning in luffa is the most outstanding problem that can result in poor quality after harvest, which would do harm to the commercial value, great economic loss included. Enzymes and polyphenols are the essential conditions and critical effects on occurring browning. In order to understand the relevance between polyphenols’content and related enzymes’ activity, this research applied 38 luffa varities as samples, fundamentally established a probability classification in luffa, linear regression with polyphenols and browning degree, and selected P-4(browning), P-6(anti-browning) these two luffas different on browning degree as samples, to make a further research on luffa growing process and polyphenols’content and activity variation of related enzymes(PPO, POD, PAL, CAT, SOD), to offer theoretical references on luffa anti-browning. The results are as followed:1. Optimizing the extraction and measuring system of luffa polyphenols:1) extractive optimization result:ethanol concentration 80%, ratio of liquid and sample: 1:10; ultrasonic temperature 40℃,30 mins; 2) measuring optimization result:wave length 750nm, reaction time 60 mins, temperature 30℃,3 mL Na2CO3 at 0.5 mol/L, 1.5 mL Folin-Ciocalteu at 0.5 mol/L.2. The research on luffa browning related enzymatic characteristics, detailed results are:1) PPO optimum reation system:catechol as substrate, optimum reation temperature of this enzyme 35℃, optimum pH6.0, reation time not more than 2.5 mins, Km 0.05 mol/L, optimum enzymatic liquid volume 0.15 mL; 2) POD optimum reation system:2-Methoxyphenol as substrate, reation time not more than 3 mins, Km 0.013 mol/L, optimum temperature 40℃, optimum enzymatic liquid volume 0.12 mL and 0.16 mL, optimum pH 5.5; 3) PAL optimum reation system:L- phenylalanine as substrate with optimum concentration 0.02 mol/L, Km 0.0835 mol/L, optimum temperature 40℃, optimum pH 8.4, optimum enzymatic liquid volume 1.4 mL; 4) SOD optimum reation system:NBT as substrate with optimum concentration 0.08 mol/L, Km 0.2079 mol/L, optimum temperature 40℃, optimum pH7.8, optimum enzymatic liquid volume 0.14 mL; 5) CAT optimum reation system:H2O2 as substrate with optimum concentration 0.33 mol/L, Km 0.1818 mol/L, optimum temperature 40℃, optimum pH 7.8, optimum enzymatic liquid volume 0.1 mL3. Probability classification in luffa browning:pulp browning degree variation within 2.17-9.60 from 38 normal luffa varities, average browning degree 6.211, variable coefficient 29.77%. Checked by Kolmogorov-Smirnov normality test, this result conforms to the rule. Applying(X-1.2818S)、(X-0.5246S)、(X+0.5246S)、 (X+1.2818S)these four points to make probability classification, put forward the standard in luffa browning degree. Luffa browning degree can be seperated into 5 levels:level 1:less than 3.84(extremely low), occupation rate 10.53%; level 2:3.84-5.24(low), occupation rate 18.42%; level 3:5.24-7.18(medium), occupation rate 36.84%; level 4:7.18～8.58(high), occupation rate 23.68%; level 5:more than 8.58 (extremely high), occupation rate 10.53%.Selecting P-4(browning),P-6 (anti-browning) these two luffas different on browning degree for further research.4. Analyze luffa linear regression with polyphenols and browning degree: measuring the polyphenols and browning degree from 38 varities, through linear regression, there is a significant linear relation between polyphenols and browning degree, equation of linear regression can be set:y (browning degree)=3.559 x (polyphenols)-2.837.5.1)Different different developmental stages of luffa:the varieties of high browning degree(P-4) and low browning degree(P-6) are various significantly at the polyphenols’ content and activity of PAL, PPO, POD, CAT, SOD. In high browning degree one, PPO, PAL have high activity; POD, SOD, CAT have low activity. Correlation analysis shows that there is a high significant positive correlation between polyphenols’ content of the high browning degree and PPO, PAL activity; a significant positive correlation between polyphenols’ content of the high browning degree and POD activity. There is a high significant positive correlation between polyphenols’ content of the low browning degree and PAL activity, a significant positive correlation between polyphenols’ content of the low browning degree and PPO activity. These can lead to a conclusion:the browning at all growing stages mainly caused by the activities of PPO, PAL, POD, which affect luffa browning together.2) Cut treatment:a significant variation in high browning degree(P-4) and low browning degree(P-6) between polyphenols’content and related enzymes’ activity. A significant positive correlation between activity of PAL and PPO, no significant positive correlation between CAT and POD, a significant positive correlation between PAL and PPO, a significant positive correlation between CAT and POD, a significant negative correlation between CAT and PAL. No significant correlation between polyphenols’ content and related enzymes’ activity in P-6, a high significant negative correlation between POD and PAL, a significant positive correlation between POD and CAT, a significant positive correlation between PPO and PAL, a significant positive correlation between PAL and CAT. According to these, the luffa browning after harvest is mainly caused by the correlation in enzymes’ activity, the correlation with phenolics is insignificant.