Extraction optimization and characterization of persimmon peel pectin extracted by subcritical water

Abstract

Persimmon peel pectin (PPP) was extracted by subcritical water via the response surface methodology. The optimal crude PPP extraction yield of 7.62 ± 0.7 % was found at 138 °C, 2.84 min, and liquid-solid ratio of 1:10.02. After treatment of deproteinization and decolorization with papain and hydrogen peroxide, 83.19 % of protein and 78.56 % of the colour in crude PPP were removed, respectively. PPP owned the <i>M_w</i> of 21.79 kDa and its uronic acids content was 64.03 %. PPP was further affirmed by fourier transform infrared, X-ray diffractometer and ¹H NMR analysis. Moreover, the degradation temperature (228.05 ℃) of PPP was verified via differential scanning calorimetry. Then, the IC₅₀ of PPP to ABTS•+ was 9.8 times that of commercial citrus pectin. Moreover, PPP could change microbial communities and selectively enrich <i>Bacteroides</i>, <i>Cetobacterium</i>, <i>Erysipelatoclostridium</i>, <i>Parabacteroides</i> and <i>Phocaeicola sartorii</i>. This study demonstrated that subcritical water was practicable for extraction of persimmon peel pectin.