To swiftly and noninvasively assess the freshness of bighead carp heads within simulated cold chain environments, an excitation-emission matrix fluorescence spectroscopy coupled with a long short-term memory network (EEM-LSTM) model was developed. Through the parallel factor algorithm based on analysis of residuals, diagnosis of core consistency, and split-half evaluation, three key fluorescent components from fish fillets were extracted, with the most significant components linked to tryptophan and NADH, both indicative of fish freshness. The EEM-LSTM model exhibited coherent trends in freshness indicators and demonstrated exceptional predictive capabilities for four freshness indicators simultaneously, achieving R2 values exceeding 0.8840 in simulated cold chain situations. Relative errors in the supermarket direct sales cold chain were less than 10%, surpassing those of the long-distance transport cold chain. Hence, the EEM-LSTM model stands validated for predicting fish freshness in simulated cold chains, holding promise for real-world aquatic product freshness forecasting within cold chain scenarios.

To swiftly and noninvasively assess the freshness of bighead carp heads within simulated cold chain environments, an excitation-emission matrix fluorescence spectroscopy coupled with a long short-term memory network (EEM-LSTM) model was developed. Through the parallel factor algorithm based on analysis of residuals, diagnosis of core consistency, and split-half evaluation, three key fluorescent components from fish fillets were extracted, with the most significant components linked to tryptophan and NADH, both indicative of fish freshness. The EEM-LSTM model exhibited coherent trends in freshness indicators and demonstrated exceptional predictive capabilities for four freshness indicators simultaneously, achieving R2 values exceeding 0.8840 in simulated cold chain situations. Relative errors in the supermarket direct sales cold chain were less than 10%, surpassing those of the long-distance transport cold chain. Hence, the EEM-LSTM model stands validated for predicting fish freshness in simulated cold chains, holding promise for real-world aquatic product freshness forecasting within cold chain scenarios.

The loss of pericarp greenness, wrinkling of the pericarp, and alteration of aroma are indicators of the ripening and senescence of lemons. In this study, lemons were soaked in 100 mg∙L-1 of gibberellin (GA) solutions for 5 min and stored at 14°C for 36 d under three relative humidity (RH) levels of 30%, 60%, and 90%, respectively. The changes in visual appearance, pigment metabolism, pericarpic microstructure, and volatile compounds of lemons during storage were evaluated. The results showed that GA pretreatment inhibited the color transformation from green to yellow of the flavedo and restrained fruit senescence. In addition, RH 90% effectively maintained the structural integrity of the oil gland, waxes, and stomata in the flavedo. GAs + RH 90% treatment maintained the fruit color index (L*, a*, b*, a*/b*, H°, C*) by inhibiting chlorophyll degradation and regulating carotenoid biosynthesis. Green lemons treated with GAs + RH 90% also showed reduced epidermal wrinkling, well-preserved cuticle, and stomatal structure, with a smooth and intact wax layer on the lemon pericarp. In addition, GAs + RH 90% treatment maintained the content of volatile aroma compounds, especially terpene. GAs + RH 90% had a great advantage in maintaining visual quality, delaying the deformation of tissue microstructure, preserving nutritional quality, and improving aroma. Thus, this treatment is potentially applicable for maintaining the storage quality of green lemons and extending their shelf life.

The loss of pericarp greenness, wrinkling of the pericarp, and alteration of aroma are indicators of the ripening and senescence of lemons. In this study, lemons were soaked in 100 mg∙L-1 of gibberellin (GA) solutions for 5 min and stored at 14°C for 36 d under three relative humidity (RH) levels of 30%, 60%, and 90%, respectively. The changes in visual appearance, pigment metabolism, pericarpic microstructure, and volatile compounds of lemons during storage were evaluated. The results showed that GA pretreatment inhibited the color transformation from green to yellow of the flavedo and restrained fruit senescence. In addition, RH 90% effectively maintained the structural integrity of the oil gland, waxes, and stomata in the flavedo. GAs + RH 90% treatment maintained the fruit color index (L*, a*, b*, a*/b*, H°, C*) by inhibiting chlorophyll degradation and regulating carotenoid biosynthesis. Green lemons treated with GAs + RH 90% also showed reduced epidermal wrinkling, well-preserved cuticle, and stomatal structure, with a smooth and intact wax layer on the lemon pericarp. In addition, GAs + RH 90% treatment maintained the content of volatile aroma compounds, especially terpene. GAs + RH 90% had a great advantage in maintaining visual quality, delaying the deformation of tissue microstructure, preserving nutritional quality, and improving aroma. Thus, this treatment is potentially applicable for maintaining the storage quality of green lemons and extending their shelf life.

Gut microbiota-associated metabolites can be synthesized endogenously or derived from dietary nutrients and host compounds. Among them, alkaloids, terpenes, and flavones originating from edible and medicinal foods have attracted remarkable interest recently and play crucial roles in metabolic diseases. The efficacy of these metabolites is susceptible to dietary intervention, especially after food processing. Therefore, this review comprehensively summarizes the different sources of common gut microbial metabolites, including microbial self-synthesis, biodegradation of exogenous substances (mainly dietary nutrients), and participation in host metabolism. In addition, the latest studies on novel metabolites such as alkaloids, terpenoids, and flavonoids are discussed, and their action mechanisms on metabolic diseases are elaborated. How food processing impacts dietary nutrients and their metabolites is carefully examined, as well as their effects on disease modification. These insights could contribute to a deeper understanding of the mechanisms by which diet efficacy helps prevent metabolic diseases, particularly through gut microbial metabolites.

Gut microbiota-associated metabolites can be synthesized endogenously or derived from dietary nutrients and host compounds. Among them, alkaloids, terpenes, and flavones originating from edible and medicinal foods have attracted remarkable interest recently and play crucial roles in metabolic diseases. The efficacy of these metabolites is susceptible to dietary intervention, especially after food processing. Therefore, this review comprehensively summarizes the different sources of common gut microbial metabolites, including microbial self-synthesis, biodegradation of exogenous substances (mainly dietary nutrients), and participation in host metabolism. In addition, the latest studies on novel metabolites such as alkaloids, terpenoids, and flavonoids are discussed, and their action mechanisms on metabolic diseases are elaborated. How food processing impacts dietary nutrients and their metabolites is carefully examined, as well as their effects on disease modification. These insights could contribute to a deeper understanding of the mechanisms by which diet efficacy helps prevent metabolic diseases, particularly through gut microbial metabolites.

Fresh walnuts (Juglans regia L.) are challenging to store due to their high water content and delicate green appearance. It has been reported that sodium nitroprusside (SNP, a nitric oxide donor) can promote stress tolerance. However, whether SNP affects the postharvest quality of fresh walnuts remains unknown. This research showed that appropriate SNP treatment contributed to walnut preservation; in particular, 0.5 mmol/L SNP treatment resulted in a better appearance and less decay (59.7%). Compared with the control, this treatment not only increased the levels of proteases related to fresh walnut disease (chitinase and β-1,3-glucanase) but also increased the overall antioxidant level and reduced oxidant damage. Moreover, respiratory metabolism and ethylene release were greatly suppressed (9.5%), and the overall sensory evaluation did not reveal any adverse effects associated with a lower acid or peroxide content. Thus, it was inferred that the optimal SNP dose activated disease-related enzymes, mediated the physiological metabolism rate, regulated the ROS-redox balance and therefore reduced decay and maintained the walnut quality. This is the first report of SNP (NO) application for the preservation of fresh walnuts and may provide information to facilitate practical application of this potential innovation.

Fresh walnuts (Juglans regia L.) are challenging to store due to their high water content and delicate green appearance. It has been reported that sodium nitroprusside (SNP, a nitric oxide donor) can promote stress tolerance. However, whether SNP affects the postharvest quality of fresh walnuts remains unknown. This research showed that appropriate SNP treatment contributed to walnut preservation; in particular, 0.5 mmol/L SNP treatment resulted in a better appearance and less decay (59.7%). Compared with the control, this treatment not only increased the levels of proteases related to fresh walnut disease (chitinase and β-1,3-glucanase) but also increased the overall antioxidant level and reduced oxidant damage. Moreover, respiratory metabolism and ethylene release were greatly suppressed (9.5%), and the overall sensory evaluation did not reveal any adverse effects associated with a lower acid or peroxide content. Thus, it was inferred that the optimal SNP dose activated disease-related enzymes, mediated the physiological metabolism rate, regulated the ROS-redox balance and therefore reduced decay and maintained the walnut quality. This is the first report of SNP (NO) application for the preservation of fresh walnuts and may provide information to facilitate practical application of this potential innovation.

Arecoline, the principal active alkaloid in the areca nut, is known for its ability to induce euphoric sensations. Since ancient times, arecoline has garnered attention for its therapeutic potential in addressing psychiatric disorders and alleviating gastrointestinal ailments. However, in 2020, the International Agency for Research on Cancer has classified arecoline as 'probably carcinogenic to humans' (Group 2B carcinogen), supported by compelling mechanistic evidence. The mechanism of action of arecoline has been extensively studied, but the results of these studies are scattered and lack systematic integration and generalization. In this paper, we have systematically summarized the mechanism of arecoline within the oral cavity, central nervous system, cardiovascular system, and digestion system, in terms of both health functions and toxic effects. In addition, we found some concentration-effect relationship between arecoline in the central nervous system and digestive system, i.e., low doses are beneficial and high doses are harmful. By summarizing the mechanisms of arecoline, this review is poised to provide in-depth and valuable insights into the clinical practice and targeted therapy of arecoline in the future.

Arecoline, the principal active alkaloid in the areca nut, is known for its ability to induce euphoric sensations. Since ancient times, arecoline has garnered attention for its therapeutic potential in addressing psychiatric disorders and alleviating gastrointestinal ailments. However, in 2020, the International Agency for Research on Cancer has classified arecoline as 'probably carcinogenic to humans' (Group 2B carcinogen), supported by compelling mechanistic evidence. The mechanism of action of arecoline has been extensively studied, but the results of these studies are scattered and lack systematic integration and generalization. In this paper, we have systematically summarized the mechanism of arecoline within the oral cavity, central nervous system, cardiovascular system, and digestion system, in terms of both health functions and toxic effects. In addition, we found some concentration-effect relationship between arecoline in the central nervous system and digestive system, i.e., low doses are beneficial and high doses are harmful. By summarizing the mechanisms of arecoline, this review is poised to provide in-depth and valuable insights into the clinical practice and targeted therapy of arecoline in the future.

Essential oils (EOs) are plant aromas used in the food industry. They have attracted considerable attention due to their diverse properties, i.e., antimicrobial, antifungal, and antioxidant activities, with natural aroma and flavor as beneficial food additives. However, the instability, degradability, and hydrophobicity of EOs have limited their practical use in the food industry. Nanoencapsulation, a process where EOs are enclosed in a protective shell at the nanoscale, promises to enhance the biological properties of EOs. This process empowers EOs with excellent physiochemical stability and solubility, allowing for better distribution in food systems and controlled release for prolonged availability of EOs without rapid evaporation and instability. This review summarizes the recent works on encapsulating EOs to enhance their biological properties, providing a comprehensive overview of various specific nano-carriers and their applications in the food industry.

Essential oils (EOs) are plant aromas used in the food industry. They have attracted considerable attention due to their diverse properties, i.e., antimicrobial, antifungal, and antioxidant activities, with natural aroma and flavor as beneficial food additives. However, the instability, degradability, and hydrophobicity of EOs have limited their practical use in the food industry. Nanoencapsulation, a process where EOs are enclosed in a protective shell at the nanoscale, promises to enhance the biological properties of EOs. This process empowers EOs with excellent physiochemical stability and solubility, allowing for better distribution in food systems and controlled release for prolonged availability of EOs without rapid evaporation and instability. This review summarizes the recent works on encapsulating EOs to enhance their biological properties, providing a comprehensive overview of various specific nano-carriers and their applications in the food industry.

Chlorophyll (Chl), the most widely distributed natural pigment in nature, is limited in use due to its poor stability. This study refers to the aggregation structure of Chl and carotene (Car) in natural photosynthetic systems, hoping to improve the photostability of Chl by constructing Chl/Car aggregates. The stability protection effect of Car on Chl was explored by designing different ratios of Chl and Car aggregation systems. The configuration of Chl/Car aggregates was optimized through ab initio molecular dynamics, and the aggregation mechanism of the aggregates and the photoprotection mechanism of Chl by Car were elucidated through quantum chemical calculations and wave function analysis. Chl/Car had a 27.22% higher Chl retention rate than free Chl after 7 d of illumination, with a Chl to Car ratio of 1.66:1. A configuration of the Chl/Car aggregates which Car's conjugated olefin chain interacts extensively with the porphyrin ring and bent phytyl chain of Chl made them more stable. The photoprotective mechanism of Car on Chl in the Chl/Car aggregates is elucidated. Car's conjugated polyene chain provides HOMO orbitals to the Chl/Car aggregates. It demonstrated that Car supplies electrons in the low-lying excited states S2 and S4, indicating it is more susceptible to damage, protecting Chl. This research will promote the development of natural color formulas and ensure the health of consumers.

Chlorophyll (Chl), the most widely distributed natural pigment in nature, is limited in use due to its poor stability. This study refers to the aggregation structure of Chl and carotene (Car) in natural photosynthetic systems, hoping to improve the photostability of Chl by constructing Chl/Car aggregates. The stability protection effect of Car on Chl was explored by designing different ratios of Chl and Car aggregation systems. The configuration of Chl/Car aggregates was optimized through ab initio molecular dynamics, and the aggregation mechanism of the aggregates and the photoprotection mechanism of Chl by Car were elucidated through quantum chemical calculations and wave function analysis. Chl/Car had a 27.22% higher Chl retention rate than free Chl after 7 d of illumination, with a Chl to Car ratio of 1.66:1. A configuration of the Chl/Car aggregates which Car's conjugated olefin chain interacts extensively with the porphyrin ring and bent phytyl chain of Chl made them more stable. The photoprotective mechanism of Car on Chl in the Chl/Car aggregates is elucidated. Car's conjugated polyene chain provides HOMO orbitals to the Chl/Car aggregates. It demonstrated that Car supplies electrons in the low-lying excited states S2 and S4, indicating it is more susceptible to damage, protecting Chl. This research will promote the development of natural color formulas and ensure the health of consumers.

In this study, static and dynamic desorption methods, infrared spectroscopy and, in vitro antioxidant modeling were used to isolate, purify, and investigate the bioactivity of melanoidins extracted from hypoheat-induced Lycium barbarum L. The results showed that melanoidin fractions with molecular weight in the range of 3−10 kDa were the dominant and most valuable fractions. In the purification phase, the optimal purification conditions were: a loading concentration of 4 mg·mL−1, elution volume of 6 BV, and an elution flow rate of 1 mL·min−1. Purified dominant melanoidin fractions (UF3) exhibited typical Maillard reaction (MR) characteristics in FTIR. The storage stability showed that sunlight and heat treatment exacerbated the instability of the purified UF3. At the same time it was relatively stable under dark conditions and incandescent light, with a retention rate of about 90%. After in vitro digestion, the purified UF3 still exhibited good antioxidant activity, and the DPPH scavenging activity and hydroxyl free radical scavenging ability reached more than 60%.

In this study, static and dynamic desorption methods, infrared spectroscopy and, in vitro antioxidant modeling were used to isolate, purify, and investigate the bioactivity of melanoidins extracted from hypoheat-induced Lycium barbarum L. The results showed that melanoidin fractions with molecular weight in the range of 3−10 kDa were the dominant and most valuable fractions. In the purification phase, the optimal purification conditions were: a loading concentration of 4 mg·mL−1, elution volume of 6 BV, and an elution flow rate of 1 mL·min−1. Purified dominant melanoidin fractions (UF3) exhibited typical Maillard reaction (MR) characteristics in FTIR. The storage stability showed that sunlight and heat treatment exacerbated the instability of the purified UF3. At the same time it was relatively stable under dark conditions and incandescent light, with a retention rate of about 90%. After in vitro digestion, the purified UF3 still exhibited good antioxidant activity, and the DPPH scavenging activity and hydroxyl free radical scavenging ability reached more than 60%.

The colonic mucosal barrier is an important component of the intestinal barrier, and its integrity is crucial for maintaining digestive tract homeostasis and normal metabolism in the body. This study aimed to elucidate the mechanisms by which malvidin-3-O-galactoside (M3G) might ameliorate colonic mucosal barrier function, from the perspective of physical barrier function and immune barrier function. Male C57BL/6J mice were given dextran sulfate sodium (DSS) to establish a mice model for colitis and then administrated with or without M3G for one week. The results showed that M3G supplementation significantly improved the disease activity index (DAI) score and colon tissue injury in mice with DSS-induced colitis. M3G improved the colonic physical barrier function by modulating the expression of mucin2 (MUC2), claudin-1, occludin, zona occludens 1 (ZO-1), and intestinal fatty acid binding protein (iFABP) in the colonic mucosa. Additionally, M3G also relieved the colonic immune barrier of mice by increasing the level of secretory immunoglobulin A (SIgA) in colon tissue and the percentages of CD4+T (CD3+CD4+) and CD8+T (CD3+CD8+) cells in colon lamina propria monocytes in mice. Furthermore, M3G down-regulated Notch signaling pathway-related proteins such as Notch1, notch intracellular domain (NICD), delta-like ligand 4 (DLL4), delta-like ligand 1 (DLL1), and hairy/enhancer of split 1 (Hes1) of colon tissue. The present results demonstrated that M3G can improve colonic mucosal barrier function by inhibiting the Notch signaling pathway.

The colonic mucosal barrier is an important component of the intestinal barrier, and its integrity is crucial for maintaining digestive tract homeostasis and normal metabolism in the body. This study aimed to elucidate the mechanisms by which malvidin-3-O-galactoside (M3G) might ameliorate colonic mucosal barrier function, from the perspective of physical barrier function and immune barrier function. Male C57BL/6J mice were given dextran sulfate sodium (DSS) to establish a mice model for colitis and then administrated with or without M3G for one week. The results showed that M3G supplementation significantly improved the disease activity index (DAI) score and colon tissue injury in mice with DSS-induced colitis. M3G improved the colonic physical barrier function by modulating the expression of mucin2 (MUC2), claudin-1, occludin, zona occludens 1 (ZO-1), and intestinal fatty acid binding protein (iFABP) in the colonic mucosa. Additionally, M3G also relieved the colonic immune barrier of mice by increasing the level of secretory immunoglobulin A (SIgA) in colon tissue and the percentages of CD4+T (CD3+CD4+) and CD8+T (CD3+CD8+) cells in colon lamina propria monocytes in mice. Furthermore, M3G down-regulated Notch signaling pathway-related proteins such as Notch1, notch intracellular domain (NICD), delta-like ligand 4 (DLL4), delta-like ligand 1 (DLL1), and hairy/enhancer of split 1 (Hes1) of colon tissue. The present results demonstrated that M3G can improve colonic mucosal barrier function by inhibiting the Notch signaling pathway.

The peel of pitaya fruit is a promising source of pectin, and non- or low-methylesterified pectin has multiple bioactivities and application scenarios. In this study, non-methylated pectin was prepared from pitaya peel and the structure was characterized. Single factor experiment and response surface methodology were conducted to optimize the procedure of ultrasonic-assisted extraction for pectin. Under the optimal conditions (solid-liquid ratio of 1:40 g·mL−1, extraction temperature at 56 °C, extraction time of 25 min and ultrasonic power of 200 W), the pectin yield was up to 9.93% ± 0.97%. Degree of methylesterification and FTIR analysis confirmed that the extracted pectin was almost non-methylesterified. The pectin possessed less linear homogalacturonan (HG) but more rhamnogalacturonan (RG) regions according to the molar ratios of monosaccharides. Meanwhile, the molecular weight of the pectin was 33.52 kDa and the crystalline index was only 0.60%. Furthermore, the nanoscale structure observed by atomic force microscopy showed that the pectin was rich in highly branched polymers. Generally, pitaya peel pectin extracted by ultrasonic-assisted extraction showed a wide range of potential use as a non-or low- methylesterified pectic substance to reach the efficient utilization of fruit waste.

The peel of pitaya fruit is a promising source of pectin, and non- or low-methylesterified pectin has multiple bioactivities and application scenarios. In this study, non-methylated pectin was prepared from pitaya peel and the structure was characterized. Single factor experiment and response surface methodology were conducted to optimize the procedure of ultrasonic-assisted extraction for pectin. Under the optimal conditions (solid-liquid ratio of 1:40 g·mL−1, extraction temperature at 56 °C, extraction time of 25 min and ultrasonic power of 200 W), the pectin yield was up to 9.93% ± 0.97%. Degree of methylesterification and FTIR analysis confirmed that the extracted pectin was almost non-methylesterified. The pectin possessed less linear homogalacturonan (HG) but more rhamnogalacturonan (RG) regions according to the molar ratios of monosaccharides. Meanwhile, the molecular weight of the pectin was 33.52 kDa and the crystalline index was only 0.60%. Furthermore, the nanoscale structure observed by atomic force microscopy showed that the pectin was rich in highly branched polymers. Generally, pitaya peel pectin extracted by ultrasonic-assisted extraction showed a wide range of potential use as a non-or low- methylesterified pectic substance to reach the efficient utilization of fruit waste.