BACKGROUND: Water is generally considered to be a safe and green solvent suitable for use in natural product extraction. In this study, an eco-friendly subcritical water method was used to extract pectin from waste jackfruit peel (JFP-S), which was compared with pectin obtained by the traditional citric acid method (JFP-C). RESULTS:The extraction process was optimized using response surface methodology (RSM), and the optimum process parameters were as follows: extraction temperature 138 ∘ C, extraction time 9.15 min, liquid / solid (L/S) ratio 17.03 mL g −1 . Under these conditions, the pectin yield was 149.6 g kg −1 (dry basis). Pectin obtained from the two extraction methods displayed a high degree of esterification and the monosaccharide composition was consistent. The galacturonic acid content of JFP-S and JFP-C was 52.27% and 56.99%, respectively. JFP-S had more hairy regions and side chains than JFP-C. The molecular weight of JFP-S was 113.3 kDa, which was significantly lower than that of JFP-C (174.3 kDa). Fourier-transform infrared spectroscopy (FTIR) indicated that two samples had similar pectin typical absorption peaks. According to differential scanning calorimetry (DSC), both JFP-S and JFP-C had relatively good thermal stability. JFP-S demonstrated lower apparent viscosity and elasticity than JFP-C. Meanwhile, the G ′ and G ′′ moduli of JFP-S were lower, which found expression in the gel textural characterization of the samples. CONCLUSION: This work showed that the subcritical water method is an efficient, time-saving, and eco-friendly technology for the extraction of pectin from jackfruit peel compared with the traditional citric acid method. The physicochemical properties of pectin could be changed during subcritical water extraction.

Spermatogonial stem cells (SSCs) have the ability to self-renew and offer a pathway for genetic engineering of the male germ line. Cryopreservation of SSCs has potential value for the treatment of male infertility, spermatogonial transplantation, and so on. In order to investigate the cryopreservation effects of different cryoprotectants on murine SSCs, 0.2 M of low-density lipoproteins (LDL), trehalose and soybean lecithin were added to the cryoprotective medium, respectively, and the murine SSCs were frozen at -80°C or -196°C. The results indicated that the optimal recovery rates of murine SSCs in the cryoprotective medium supplemented with LDL, trehalose and soybean lecithin were 92.53, 76.35 and 75.48% at -80°C, respectively. Compared with freezing at -196°C, the optimum temperature for improvement of recovery rates of frozen murine SSCs, cryopreservation in three different cryoprotectants at -80°C, were 17.11, 6.68 and 10.44% respectively. The recovery rates of murine SSCs in the cryoprotective medium supplemented with 0.2 M LDL were significantly higher than that of other cryoprotectants (P < 0.05). Moreover, the recovery rates were demonstrated to be greater at -80°C compared with at -196°C (P < 0.05). In conclusion, 0.2 M of LDL could significantly protect murine SSCs at -80°C. In the freezing-thawing process, LDL is responsible for the cryopreservation of murine SSCs because it can form a protective film at the surface of membranes. However, more research is needed to evaluate and understand the precise role of LDL during the freezing-thawing of SSCs.

effects of low-density lipoproteins, trehalose and soybean lecithin on murine spermatogonial stem cells. Zygote.