Evaluation of aroma characteristics of Penaeus vannamei with different drying methods using HS-SPME-GC-MS, MMSE-GC-MS, and sensory evaluation.

The effects of microwave drying (MD), hot air drying (HAD), vacuum hot air drying (VD), and vacuum freeze drying (VFD) on the volatile profiles of Penaeus vannamei were investigated. A total of 89 and 94 volatile compounds were identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and monolithic material sorptive extraction gas chromatography-mass spectrometry (MMSE-GC-MS), respectively. Orthogonal partial least squares-discriminant analysis (OPLS-DA) and variable influence on projection (VIP) models were utilized to select characteristic volatiles and key marker compounds (e.g., octanal, 1-octen-3-ol, 2-methyl-butanal, 2-ethyl-furan, and trimethyl-pyrazine) to discriminate among four drying methods. Based on synthesis of odor descriptions and sensory evaluation, it was found that P. vannamei via MD, HAD, and VD greatly reduced the fishy and generated roasted, fatty, and smoked odors. This study systematically analyzed the aroma characteristics of four traditional dried P. vannamei products, which may provide theoretical guidance for industrial production.

Cryoprotective effect of epigallocatechin gallate replacing sucrose on Hypophythalmichthys molitrix surimi during frozen storage.

BACKGROUND: The present study aimed to investigate the cryoprotective effect of epigallocatechin gallate (EGCG) replacing sucrose on surimi during frozen storage. Substitution or partial substitution of 0.1% EGCG for sucrose (1.5%) was added to surimi, and the surimi samples without and with commercial cryoprotectants (4% sucrose and 4% sorbitol) were used as the control group. RESULTS: The results obtained suggest that, with the increase in frozen storage time, the structural performance of surimi protein gradually weakened (e.g. the decrease in the surface hydrophobicity, the increase in the total sulfhydryl and solubility, and the protein myosin heavy chain bands became shallow) and surimi gel quality gradually deteriorated (e.g. the decrease in water-holding capacity, gel strength and all texture profile attributes). However, compared with the other three group surimi samples during the frozen period, the surimi proteins with partial replacement of sucrose by EGCG had a higher total sulfhydryl group content and solubility of proteins, as well as lower surface hydrophobicity of protein, suggesting that the addition of EGCG as a partial substitute for sucrose can enhance the antifreeze ability of surimi. Meanwhile, the surimi gel with the partial replacement of sucrose by EGCG had a higher water retention capacity, gel strength and texture attributes (e.g. hardness, springiness, cohesiveness, chewiness, and resilience), indicating that the addition of EGCG as a partial substitute for sucrose can inhibit the deterioration of surimi gel quality. CONCLUSION: Overall, EGCG partially replacing sucrose can play an alternative cryoprotectant with a lower sweetness to prevent the quality of surimi from deteriorating. © 2024 Society of Chemical Industry.

Changes of Physicochemical Characteristics and Flavor during Suanyu Fermentation with Lactiplantibacillus plantarum and Saccharomyces cerevisiae.

This study investigates the changes of the physicochemical characteristics and flavor of fermented Suanyu (Chinese fermented fish) during fermentation with Lactiplantibacillus plantarum (L. plantarum) and Saccharomyces cerevisiae (S. cerevisiae). The related indicators, including pH, water activity (Aw), volatile base nitrogen (TVB-N), thiobarbituric acid (TBA), free amino acids (FAAs), microbial community, and volatile compounds were determined. L. plantarum fermentation samples (LP) and natural fermentation samples (NF) were used as controls. The pH and Aw of three groups of Suanyu samples decreased continuously through the entire fermentation process. Meanwhile, the TVB-N of three groups of samples increased gradually, while TBA first increased and then decreased. Notably, the pH, Aw, TVB-N, and TBA of MF group samples (inoculated L. plantarum and S. cerevisiae) were significantly lower than the NF group samples. In addition, both TVB-N and TBA of the MF group samples were lower than those of the LP group samples during fermentation, suggesting that combined fermentation could inhibit the growth of undesirable microorganisms more effectively. Lactobacillus were the main bacterial genus of the three group fermented samples during fermentation, and combined fermentation could promote the growth of Lactobacillus more significantly. In addition, the highest content of umami (145.16 mg/100 g), sweet amino acids (405.75 mg/100 g), and volatile compounds (especially alcohols and esters) were found in MF group samples, followed by the NF and LP group samples, indicating that combined fermentation could give Suanyu a better flavor quality. This study may provide a theoretical basis for the industrial production of fermented fish products and the improvement of fermentation technology.

Assessing the Gel Quality and Storage Properties of Hypophythalmalmichthys molitrix Surimi Gel Prepared with Epigallocatechin Gallate Subject to Multiple Freeze-Thaw Cycles.

Epigallocatechin gallate (EGCG) with concentrations of 0-0.03% was added to manufacture surimi gels, respectively, while effects on gel quality and storage properties indicators during freeze-thaw (F-T) cycles were investigated. The results implied that the gel quality and storage properties of surimi gels added without EGCG were seriously destroyed during F-T cycles. The addition of EGCG could inhibit the decline of texture and gel strength. Moreover, EGCG has effect on inhibiting the microbial growth and the formation of off-odor compounds such as total volatile basic nitrogen (TVB-N) and malondialdehyde (MDA). Low-field nuclear magnetic resonance (LF-NMR) and water-holding capacity (WHC) results showed that immobilized water migrated to free water with the extension of F-T cycles. The scanning electron microscope (SEM) observed denser protein networks and smaller holes from the surimi gels added with EGCG. However, excessive (0.03%) EGCG showed the loose network structure and moisture loss. Overall, EGCG in 0.01-0.02% addition was good for resisting damage of surimi gels during F-T cycles.

Personality first in emotion: a deep neural network based on electroencephalogram channel attention for cross-subject emotion recognition.

In recent years, more and more researchers have focused on emotion recognition methods based on electroencephalogram (EEG) signals. However, most studies only consider the spatio-temporal characteristics of EEG and the modelling based on this feature, without considering personality factors, let alone studying the potential correlation between different subjects. Considering the particularity of emotions, different individuals may have different subjective responses to the same physical stimulus. Therefore, emotion recognition methods based on EEG signals should tend to be personalized. This paper models the personalized EEG emotion recognition from the macro and micro levels. At the macro level, we use personality characteristics to classify the individuals' personalities from the perspective of 'birds of a feather flock together'. At the micro level, we employ deep learning models to extract the spatio-temporal feature information of EEG. To evaluate the effectiveness of our method, we conduct an EEG emotion recognition experiment on the ASCERTAIN dataset. Our experimental results demonstrate that the recognition accuracy of our proposed method is 72.4% and 75.9% on valence and arousal, respectively, which is 10.2% and 9.1% higher than that of no consideration of personalization.