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Polysaccharides in brown algae, including the kelp Laminaria japonica, are economically important to both food and pharmaceutical industries. The method used to extract polysaccharides significantly influences their characteristics and functions. In this study, L. japonica polysaccharides (LJP) were extracted using four techniques: hot-water extraction (HWE), ultrasound-assisted extraction (UAE), enzyme-assisted extraction (EAE), and acid-assisted extraction (AAE). The highest yield (9.73 ± 0.29 %) and sulfate content (12.47 ± 0.79 %) were obtained via UAE, whereas EAE yielded the highest total carbohydrate content (53.50 ± 1.38 %), with an extraction yield of 9.12 ± 0.13 %. The minimum molecular weight (Mw) was found after AAE, whereas a higher Mw was obtained after EAE and HWE, and a homogeneous Mw was obtained after UAE. All four LJP extracts contained a helix-coil conformation based on Congo red staining, with five monosaccharides, fucose, galactose, mannose, xylose, and glucuronic acid, in varying proportions. Polysaccharides extracted via EAE and UAE exhibited higher antioxidant activity with morphological and conformation changes. A significant correlation was noted between sulfate content and antioxidant activity, and antioxidant capacity was positively correlated to mannose content rather than uronic acid. The results indicate UAE to be the best of the four extraction methods for polysaccharides with homogeneous Mw and high antioxidant activity. This study sheds light on the effects of extraction processes on the physiochemical characteristics of polysaccharides and the relationship between chemical composition and antioxidant activities.

The aim of this study was to evaluate the effectiveness of bacteriophage (phage) SLMP1 to reduce Salmonella Typhimurium on contaminated raw salmon fillets and scallop adductors as a function of Salmonella inoculum level, phage dose, storage temperature, and storage time. Samples were inoculated with 102 and 104 CFU/g Salmonella and then treated with different concentrations of phage SLMP1, followed by incubation at 4, 15, and 25°C, respectively. The results showed that 108 PFU/g was the optimal concentration of phage for the control of Salmonella, which was applied in the following storage experiments over a 7-day period at 4°C, a 4-day period at 15°C, and a 2-day period at 25°C. For the salmon fillets samples, 102 CFU/g Salmonella could be reduced below the detection limit at all three temperatures, whereas 104 CFU/g Salmonella was first decreased and then increased at 15 and 25°C. For the scallop adductors samples, 102 CFU/g Salmonella could be reduced below the detection limit first and then i...

A rapid and efficient method for extracting Mnoiodo-tyrosine (MIT) and Diiodo-tyrosine (DIT) from laminaria was successfully developed. The laminaria samples were first pretreated with microwaves, before the MIT and DIT were extracted with an ultrasonic water bath. A response surface experiment was used to optimize the extraction conditions, and ultimately the best conditions for extraction were successfully identified, which were a microwave power of 250 W, a microwave time of 4.7 min, an addition of 0.31 g of pancreatin, and 4.22 h in the ultrasonic water bathe. A simple and low-cost High-Performance Liquid Chromatography High-Performance Liquid Chromatography Photodiode Array (HPLC-PDA) detection method for MIT and DIT was established. The detection limits ranged from 50.6 to 320.6 ng/g. Scanning Electron Microscopy (SEM) was used to observe the degree of damage to the laminaria cells from the different extraction methods. The molecular weight distribution of the organic iodine of the original laminaria and the laminaria after enzymatic hydrolysis was studied by Size-Exclusion Chromatography Inductively Coupled Plasma Mass Spectrometry (SEC-ICP-MS).