Chemical composition and physicochemical properties of red seaweed (Kappaphycus alvarezii) and brown seaweed (Sargassum polycystum) from Sabah, Malaysia

The proximate composition, amino acid composition and some physico-chemical properties of two type of seaweeds Kappaphycus alvarezii and Sargassum polycystum which widely cultivated in Sabah, Malaysia were investigated. S. polycystum showed the highest level of protein and crude fibre with 11.69% and 39.863% dry weight, respectively. Minor component was fat 0.12-0.13% in both seaweeds. As for the physicochemical properties of the seaweeds, their swelling capacity (SWC) ranged from 13.33 to 35.83 mL/g while water retention capacity (WRC), and oil retention capacity (ORC) ranged from 8.18 to10.59 g/g dry weight and 2.68 to 3.32 g/g dry weight, respectively. SWC and ORC of K. alvarezzi was higher than S. polycystum (p<0.05). Both seaweeds contained high amounts of minerals and balanced amino acid profiles. This study suggested that K. alvarezzi has high nutritional value which could be potentially used as ingredients in human food application

Effect of grinding on physicochemical properties of dietary fibre powder from pink guava by-products

This study was aimed to evaluate the effect of grinding on physicochemical properties of dietary fibre powder (DFP) from pink guava by-products for potential applications in foods. The DFP were divided into three groups of by-product which are refiner waste (RW), siever waste (SW) and decanter waste (DW). The studied samples were analysed for its particle size distribution, bulk density, water-retention capacity, oil-retention capacity, swelling capacity, and particle structures. For particle size distribution, the largest amount of DFP were retained on the 425 μm and 250 μm screen sizes except for RW where 66% of the particle size was more than 600 μm. For bulk density, all large-size particles of DFP showed lower density than small-size ones as smaller particles size would have a higher packing density due to the increase in porosity. The reduction in particle size resulted in increased hydration properties for SW and DW. On the other hand, a decrease in particle size of RW had decreased the ability of hydration properties. A similar trend of oil-retention capacity (ORC) of DFP was evident. ORC was found to increase with smaller particle size for SW and DW and no significant difference (p>0.05) for RW. The study of microstructures revealed that the grinding process resulted in the rupture of the hollow physical structure of fibre matrix and in a scale type structure, thereby providing increased surface area for water and oil absorption. As a result, DFP pink guava could be used not only for dietary fibre enrichment, but also as functional ingredients in many food products

Effect of drying methods on nutrient composition and physicochemical properties of Malaysian seaweeds

Sample drying is an important step in the sample preparation of materials. In this study, the effects of two drying methods which are oven-drying and freeze-drying on the proximate composition, mineral content and physicochemical properties of seaweeds Kappaphycus alvarezii and Sargassum polycystum were investigated. There were significant differences (p< 0.05) in the moisture, fat, crude protein, crude fiber and ash contents of both seaweeds treated by different drying methods. The highest values of nutrient composition were detected in the moisture, protein, crude fiber and fat content of samples treated with the oven-dried method. In contrast, the amount of ash and mineral in both seaweeds were found higher in freeze-dried compared to oven-dried. As for the physicochemical properties of both seaweeds, swelling capacity and water retention capacity of freeze-dried K. alvarezii were significantly higher than those of the oven-dried seaweed samples (p< 0.05). Thus, the results show that the nutritional composition of seaweeds S. polycystum and K. alvarezii are greatly affected by different drying methods