Optimization extraction, characterization and anticancer activities of polysaccharides from mango pomace.

Response surface methodology was used to optimize the extraction conditions for ultrasonic-assisted extraction of polysaccharides from mango pomace. The Optimum extraction conditions consisted of extraction temperature of 74 °C, ultrasonic power of 170 W, extraction time of 100 min, and raw material-to-water ratio of 1:40 g/mL. Under these conditions, the extraction yield was 3.71 ±â€¯0.07%. Three novel polysaccharide fractions, MG-1, MG-2 and MG-3 were purified from the crude polysaccharides by using DEAE-52 cellulose and Sephadex G-100 column chromatography. The molecular weight and monosaccharide composition of polysaccharide fractions (MPFs) were analyzed by high performance liquid gel permeation chromatography (HPGPC) and HPLC analysis, respectively. The characterizations of MPFs were conducted with FT-IR, 1H NMR and SEM. Furthermore, the anticancer activities of the polysaccharide fractions were also investigated in vitro. Results showed that MG-1, MG-2 and MG-3 exhibited significant anticancer activities against HepG2, MCF-7, A549, HeLa, A2780, HCT-116 and BGC-823 cells in a dose-dependent manner. MPFs were also showed to promote apoptosis as seen in the nuclear morphological examination study using calcein acetyl methoxy methyl easter (calcein-AM) and propidium iodide (PI) staining. This research could serve as a theoretical reference for the efficient utilization of MPFs in biomedical and functional food.

Effects of wax treatment on the physiology and cellular structure of harvested pineapple during cold storage.

Pineapple (Ananas comosus (L.) Merr. cv. 'Paris') is sensitive to low temperature and highly susceptible to blackheart during cold storage, which causes serious fruit decay. This work investigated the effect of wax treatment (Sta-Fresh 2952, 60 g/L) on blackheart of pineapple under chilling stress. Wax treatment significantly reduced blackheart symptoms after 14 days of storage and markedly delayed changes in firmness and flesh color during the whole period of storage. The weight loss of wax-treated fruit (2.6%) was less than the control (3.1%) at the 24th day of storage. The treatment decreased the activities of PG and EGase for maintaining cell wall stability during the later period of storage. In the control fruit, the structure of flesh cells was significantly damaged under chilling stress, with looser cell wall, absence of middle lamella, loss of membrane integrity, and many cells near the vascular tissue collapsed. The subcellular elements could be barely observed in the control after storage. These destructive symptoms were significantly alleviated in the wax-treated fruit. The results suggest that wax treatment could reduce blackheart of pineapple under chilling stress via maintenance of cell integrity.