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The effect of phlorotannin extracts (PTE) (from sporophyll of Undaria pinnatifida) added at different levels (0, 25, 125, 625 µmol/g protein) on the gel properties of mackerel (Scomberomorus niphonius) myofibrillar protein (MP) was studied with and without ultraviolet A (UVA) irradiation. The results showed that the gel strength and cooking yield increased in a PTE dose-dependent manner, and at the level of 625 µmol/g protein PTE, the highest gel strength of 308.43 ± 8.12 (mN·cm) and cooking yield of 76.16 ± 1.40% were obtained in the samples treated with UVA irradiation. The same samples also showed increased carbonyl content, decreased total sulfhydryl, unwinding of α-helix, and quenching of fluorescence intensity of endogenous tryptophan, all of which indicated that elevated protein oxidation in these samples led to enhanced protein cross-linking. Results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated aggregation of myosin heavy chains (MHCs) in the UVA-treated gels with PTE, also evidenced by the dense three-dimensional network structure in these samples visualized by scanning electron microscopy (SEM). Electron spin resonance (ESR) and spin trapping results indicated that free radicals were produced during the gelation process, possibly originated from UVA-treated PTE, which played a critical role of oxidizing fish MPs, and eventually led to the improvement of the textural properties of the mackerel MP gel. PRACTICAL APPLICATION: Brown algae are a family of high-yield marine algae. Phlorotannin extracts are highly active natural substances extracted from brown algae that can have many applications. Ultraviolet A (UVA) as a green and environmentally friendly physical processing method has been widely used in food processing in recent years. The method proposed in this study could be utilized to improve properties of fish protein gel made from poorly performing low-priced fishes, and provide workable guidance for industry to expand the application of brown algae in food processing to better meet consumer's demand for high-quality marine foods.

Different heating conditions could change water absorption capacity of sea cucumbers body wall (SCBW), and subsequently affect the sensory quality of the rehydrated sea cucumbers. In this study, fresh SCBWs were boiled for 30, 60, 90, 120, 150, 180 min, respectively. The boiled SCBWs were then soaked in deionized water for 48 hr. The changes in water absorption ratio (Wabs ), water holding capacity, water distribution, texture and ultrastructure of the SCBW were investigated. With increasing cooking time (from 30 to 180 min) the water absorption capacity is significantly enhanced (from 1.84 times to 3.37 times). The absorbed water was found to exist inside the SCBW in two forms, physisorbed water, which entered the SCBW via diffusion and could be easily removed, and associated water, which formed association with the SCBW structure, evidenced by the difference in mobility determined by low field nuclear magnetic resonance (LF-NMR) spectroscopy. Study of the microstructure of the SCBW showed that the collagen fibers in the SCBW gradually depolymerized and degraded, resulting in the formation of inter-fiber pores and gaps which became internal space that could accommodate more and more water as the cooking time increased. This water was mainly physisorbed with high mobility. The texture characteristics of the SCBW negatively correlated with the accumulation of physiosorbed water. These findings suggest that proper control of heating time could be critical in determining the sensory/eating quality of sea cucumbers. PRACTICAL APPLICATION: Different heating conditions allows sea cucumbers to have different water absorption capacity during the subsequent soaking process, which could greatly affect sea cucumber sensory quality. Understanding the effects of heating on the water absorption characteristics and texture characteristics of sea cucumber body wall will provide knowledge basis and guidelines to optimize the processing parameters for the emerging ready-to-eat sea cucumber industry.

To effectively extract biogenic amines (BAs) from complex food matrices is an important issue. In this study, a stop-and-go-extraction tip (StageTip)-based method for simultaneous enrichment of six BAs including histamine, tyramine, putrescine, cadaverine, tryptamine, and β-phenylethylamine in fish samples was developed and optimized. This StageTip-based BAs extraction method required short extraction time, small sample size, and minimal consumption of organic solvents. In addition, an ultrahigh-performance liquid chromatography coupled with triple quadrupole mass spectrometer was used to identify and quantify BAs without derivatization. Target recovery efficiencies of BAs from spiked fish samples ranged from 84% to 110%. Linear regression models were established to determine BAs in the range of 0.4 to 3.0 mg/L (R2 > 0.995). Good repeatability was obtained with relative standard deviation of peak areas (1.17 to 5.61%) and retention time (0.09 to 0.20%). High sensitivity was achieved for the detection of six BAs (0.064 to 1.00 ng/L for the limit of detection, 0.10 to 5 ng/L for the limit of quantification). The proposed method had an obvious advantage in the analysis of BAs in complex food matrices such as fish tissues since it could reflect the subtle distribution of BAs from one fish fillet. PRACTICAL APPLICATION: A StageTip-based BAs enrichment combined with UPLC-MS analysis method was developed and optimized, which was low-cost, environmentally friendly, and with good analytical performances. As such, it has the potential to become a powerful tool for the analysis of BAs in different complex food matrices.

Different heating conditions could change water absorption capacity of sea cucumbers body wall (SCBW), and subsequently affect the sensory quality of the rehydrated sea cucumbers. In this study, fresh SCBWs were boiled for 30, 60, 90, 120, 150, 180 min, respectively. The boiled SCBWs were then soaked in deionized water for 48 hr. The changes in water absorption ratio (W

A fast and easy-to-operate Fourier Transform Infrared (FTIR) spectrometry-based approach was developed for microbial differentiation and quantiffcation in apple juice. Eight different microorganisms were eevaluated. Enterobacter cloacae, Salmonella typhimurium, Enterobacter aerogenes, Salmonella choleraesuis, Serratia marcescens, Pseudomonas vulgaris, Vibria cholerae, and Hafnia alvei. FTIR spectrascopy combined with chemometrics could differentiate the microorganisms studied at low concentration level of 10° colony-forming units (CFU)/mL in apple jeice. The chemometric models developed to count microorganisms in apple juice were valldated by an indepen dent test set consisting of 18 samples and correlated against plate counts satisfactorily up to a detection limit of 10 3 CFU/mL.

Seven selective differential plating media were evaluated for their effectiveness in recovering eight serotypes (0:3; 0:8; 0:9; 0:11,24; 0:12,25; 0.16; 0:17; and 0:28) of Y. enterocolitica from pure cultures and from artificially inoculated fresh ground pork homogenate. Cefsulodin-irgasan-novobiocin (CIN) agar was the most effective medium for the recovery of Y. enterocolitica. However, Y. enterocolitica 0:12,25 was slightly inhibited on CIN agar. Bismuth sulfite agar, MacConkey, and MacConkey-Tween 80 agars were acceptable; cellobiose-arginine-lysine, desoxycholate citrate, and Salmonella-Shigella agars were the least effective media.