Polysaccharides from pineapple core as a canning by-product: Extraction optimization, chemical structure, antioxidant and functional properties

Ultrasonic-assisted extraction (UAE) technique has been investigated to extract polysaccharides from pineapple core as a by-product using response surface methodology. A Box–Behnken design was employed to optimize the conditions for the maximum extraction yield of polysaccharides. The results demonstrated that the optimum extraction conditions were as follows: water/solid material ratio of 29.5 mL/g, extraction temperature of 66.3 °C and extraction time of 46.7 min. Under these conditions, the extraction yield of pineapple core polysaccharides (PCPs) was 16.7%. The structure of PCPs was analyzed by Fourier transform-infrared spectroscopy (FT-IR) analysis, X-ray diffractometry (XRD), SEM (scanning electron microscope) and gas chromatography–mass spectrometry (GC–MS). The results of thermogravimetric analysis indicated that the PCPs had a good thermal stability at temperatures below 250 °C. The extracted polysaccharides had a porous structure with rough surface. The extracted polysaccharides had strong scavenging activities on DPPH and hydroxyl radicals. Furthermore, they demonstrated interesting water-holding and fat-binding capacities (3.11 and 4.25 g/g, respectively). The results revealed that polysaccharides displayed good emulsifying and foaming properties. Overall, the findings suggest that PCPs are a promising source of antioxidants and may have potential applications in functional food industries.