Omnifarious fruit polyphenols: an omnipotent strategy to prevent and intervene diabetes and related complication?

Diabetes mellitus is a metabolic syndrome which cannot be cured. Recently, considerable interest has been focused on food ingredients to prevent and intervene in complications of diabetes. Polyphenolic compounds are one of the bioactive phytochemical constituents with various biological activities, which have drawn increasing interest in human health. Fruits are part of the polyphenol sources in daily food consumption. Fruit-derived polyphenols possess the anti-diabetic activity that has already been proved either from in vitro studies or in vivo studies. The mechanisms of fruit polyphenols in treating diabetes and related complications are under discussion. This is a comprehensive review on polyphenols from the edible parts of fruits, including those from citrus, berries, apples, cherries, mangoes, mangosteens, pomegranates, and other fruits regarding their potential benefits in preventing and treating diabetes mellitus. The signal pathways of characteristic polyphenols derived from fruits in reducing high blood glucose and intervening hyperglycemia-induced diabetic complications were summarized.

Interaction of Soy Protein Isolate Hydrolysates with Cyanidin-3-O-Glucoside and Its Effect on the In Vitro Antioxidant Capacity of the Complexes under Neutral Condition.

The interaction of soy protein isolate (SPI) and its hydrolysates (SPIHs) with cyanidin-3-O-glucoside (C3G) at pH 7.0 were investigated to clarify the changes in the antioxidant capacity of their complexes. The results of intrinsic fluorescence revealed that C3G binds to SPI/SPIHs mainly through hydrophobic interaction, and the binding affinity of SPI was stronger than that of SPIHs. Circular dichroism and Fourier-transform infrared spectroscopy analyses revealed that the interaction with C3G did not significantly change the secondary structures of SPI/SPIHs, while the surface hydrophobicity and average particle size of proteins decreased. Furthermore, the SPI/SPIHs-C3G interaction induced an antagonistic effect on the antioxidant capacity (ABTS and DPPH) of the complex system, with the masking effect on the ABTS scavenging capacity of the SPIHs-C3G complexes being lower than that of the SPI-C3G complexes. This study contributes to the design and development of functional beverages that are rich in hydrolysates and anthocyanins.

Effects and mechanisms of using "clean" smoke particles in the smoking process on the formation of ß-carboline heterocyclic amines (ß-CHAs) in smoked meat patties.

ß-Carboline heterocyclic amines (ß-CHAs), known for their synergistic neurotoxic and carcinogenic effects, are predominantly produced by humans through cigarette smoke and food and are found particularly in meats cooked at high temperatures. Few studies have explored the differences in the mechanisms of accumulation of ß-CHAs in smoked meat and meat processed at high temperatures. In this research, the concentration of ß-CHAs in smoked meats prepared using a variety of wood materials was measured using LCMS/MS. Additionally, key volatile organic compound markers associated with ß-CHAs accumulation in smoke were identified through GCMS and multivariate statistical analysis and subsequently confirmed in a chemical simulation system. Three types of strainers, each with a distinct aperture size, were used to assess the efficacy of particle filtration in reducing ß-CHAs levels in smoked meat. The findings indicated that smoke exposure indeed increases the ß-CHAs content of meat. However, only the strainer capable of filtering PM2.5-sized particles reduced the amount of ß-CHAs present compared to the control group. In contrast, strainers with larger pore sizes facilitated excessive accumulation of ß-CHAs. The presence of aldehydes such as 1 H-pyrrole-2-carboxaldehyde, 5-methylfurfural, benzaldehyde, furfural, and nonanal exhibited a positive correlation with the accumulation of ß-CHAs. Conversely, phenolic compounds, including 2-methoxy-4-vinylphenol, 2-methoxy-5-methylphenol, p-cresol, phenol, 2-methoxy-4-(1-propenyl)-, (Z)-, phenol, 3-ethyl-, and phenol, 4-ethyl-2-methoxy-, showed a negative correlation. Thus, filters made from chelated carbonyl trap materials both chemically and physically disrupt the buildup of ß-CHAs in smoked meats. The use of this approach will not only improve the quality of these products but will also contribute to decreasing the amount of inhalation pollutants released into the environment.

Entrapment of cyanidin-3-O-glucoside in ß-conglycinin: From interaction to bioaccessibility and antioxidant activity under thermal treatment.

The thermal-induced interaction between ß-conglycinin (7S) and cyanidin-3-O-glucoside (C3G) on the bioaccessibility and antioxidant capacity of C3G was investigated. High ratio of 7S to C3G (1:100) led to a more ordered secondary structure of 7S. Thermal treatment promoted the formation of 7S-C3G complexes via hydrophobic and hydrogen bonds but did not induce the formation of 7S-C3G covalent products. Thermal treatment at 65 °C and 121 °C enhanced the binding affinity of 7S-C3G complexes by 46.19 % and 1203 % compared with 25 °C. The 7S-C3G interaction decreased C3G bioaccessibility by 4.37 %, 8.74 %, and 46.37 % at 25 °C, 65 °C, and 121 °C. Diphenylpicrylhydrazyl (DPPH) and ABTS antioxidant capacity assay indicated an antagonistic effect between 7S and C3G. The increased binding affinity of C3G to 7S limited the bioaccessibility of C3G and promoted the antagonism of antioxidant capacity between 7S and C3G. 7S addition was detrimental to the antioxidant capacity and bioaccessibility of C3G in vitro after thermal processing.

Improved Light and In Vitro Digestive Stability of Lutein-Loaded Nanoparticles Based on Soy Protein Hydrolysates via Pepsin.

In order to improve the water solubility and stability of lutein, soy protein isolates (SPI) and their hydrolysates via pepsin (PSPI) and alcalase (ASPI) were used as nanocarriers for lutein to fabricate the lutein-loaded nanoparticles (LNPS) of SPI, PSPI, and ASPI. The encapsulation properties, light, and in vitro digestive stability of lutein in nanoparticles, and protein-lutein interactions were investigated. Compared with SPI-LNPS and ASPI-LNPS, PSPI-LNPS was characterized by uniform morphology (approximately 115 nm) with a lower polydispersity index (approximately 0.11) and higher lutein loading capacity (17.96 µg/mg protein). In addition, PSPI-LNPS presented the higher lutein retention rate after light exposure (85.05%) and simulated digestion (77.73%) than the unencapsulated lutein and SPI-LNPS. Fluorescence spectroscopy revealed that PSPI had stronger hydrophobic interaction with lutein than SPI, which positively correlated with their beneficial effects on the light and digestive stability of lutein. This study demonstrated that PSPI possessed significant potential for lutein delivery.

The effects of ß-lactoglobulin on cyanidin-3-O-glucoside antioxidant activity and bioaccessibility after heat treatment.

The impact of heat treatment at different temperatures on the interaction of ß-lactoglobulin (ß-Lg) and anthocyanin-3-O-glucoside (C3G) was studied. Heat treatment and the addition of C3G changed the secondary structure of ß-Lg with decreasing ß-sheets and increasing random coils. Interactions between C3G and ß-Lg were mainly via hydrogen bonds and van der Waals forces at 25 °C. The elevated temperature promoted hydrophobic interactions between C3G and ß-Lg due to an increase in the hydrophobic groups and amino groups on the surface of ß-Lg molecules. The addition of ß-Lg to the C3G eliminated heat-induced thermal degradation of C3G. The ß-Lg-C3G interactions accompanied with increased particle size and constant zeta potential could increase the antioxidant capacity of C3G approximately by 4% to 10% and protect the colour of C3G from degradation under heat treatment. The C3G bioaccessibility with ß-Lg addition increased by 26.08%, 33.45%, 83.09%, 72.27%, and 354.62% compared with C-25, C-60, C-85, C-100, and C-121, respectively. The protective effect of the non-covalent interactions on C3G at high temperatures (85 °C to 121 °C) was significantly stronger than at 25 °C and 60 °C. The application of ß-Lg in foodstuffs could enhance the antioxidant activity and bioaccessibility of C3G.

In vitro phenolic bioaccessibility of coffee beverages with milk and soy subjected to thermal treatment and protein-phenolic interactions.

The effect of skimmed bovine milk and soy protein on the in vitro bioaccessibility of polyphenols in coffee beverages under thermal treatment (25, 90, and 121 °C) and the protein-phenolic interaction was investigated. Thermal treatment at 90 °C and 121 °C reduced the in vitro bioaccessibility of total and individual phenolic. Skimmed milk and soy protein addition increased the total (by 37.01%-64.21% and 24.74%-47.32%, respectively) and individual phenolic in vitro bioaccessibility (by 4.40%-27.29% and 12.02%-28.61%, respectively) of coffee beverages subjected to thermal treatment at 25, 90 and 121 °C. Compared with soy protein, skimmed milk significantly enhanced the in vitro bioaccessibility of coffee polyphenols, possibly owing to the presence of different types and strengths of noncovalent protein-phenolic interactions. These findings can provide certain theoretical knowledge for optimizing the processing technology and formula of the food industry to help improve the health benefits of milk coffee beverages.

Effect of preheated milk proteins and bioactive compounds on the stability of cyanidin-3-O-glucoside.

Native and preheated whey protein isolates (WPI) and casein (at 55 °C-90 °C) were used as protective carriers. Three bioactive compounds, including (-)-Epigallocatechin-3-gallte (EGCG), gallic acid, and vitamin C, were added to enhance the stability of cyanidin-3-O-glucoside (C3G). Under acidic (pH 3.6) and neutral (pH 6.3) conditions, both native and preheated milk proteins showed significant protective effect on C3G. WPI preheated at 85 °C presented the best protective effect on C3G under neutral condition by reducing its thermal, oxidation, and photo degradation rates 25.0%, 38.0%, and 41.1%, respectively. The addition of vitamin C into the protein-anthocyanin solutions accelerated the color loss of C3G, whereas EGCG and gallic acid improved its thermal stability. Among the bioactive compounds, gallic acid provided the most significant protective effect on C3G by further decreasing the thermal degradation rate of C3G 44.6% as a result of the formation of 85 °C preheated WPI-gallic acid-C3G complexes.

Competitive interactions among tea catechins, proteins, and digestive enzymes modulate in vitro protein digestibility, catechin bioaccessibility, and antioxidant activity of milk tea beverage model systems.

This work aimed to study the effects of the competitive interaction among tea catechins, milk proteins, and digestive enzymes on protein digestibility, catechin bioaccessibility, and antioxidant activity by simulating in vitro digestion. The inhibitory effect of catechins on digestive enzymes was positively correlated with the binding affinity of catechins to digestive enzymes. The interaction between tea catechins and milk proteins or digestive enzymes resulted in the reduction of protein digestibility. The bioaccessibility of catechins and antioxidant activity of the milk tea beverage were reduced by protein-catechin interaction, but they increased via competition among proteins, catechins, and digestive enzymes. After the addition of ß-lactoglobulin (ß-Lg), epigallocatechin gallate (EGCG), epigallocatechin (EGC), and epicatechin (EC) bioaccessibility increased by 252.6%, 85.0%, and 37.0%, respectively. The addition of ß-casein (ß-CN) negatively affected EGCG and EGC bioaccessibility but significantly increased EC bioaccessibility. The addition of ß-Lg and ß-CN showed better protective effects on antioxidant activity. The bioaccessibility of tea catechins mixed with ß-Lg is significantly higher than that of tea catechins mixed with ß-CN in the gastrointestinal digestion stage, except for the mixture of EC and ß-CN. The increase in catechin bioaccessibility and antioxidant activity was positively correlated to the binding affinity of catechins-proteins.

Analysis of the interaction between cyanidin-3-O-glucoside and casein hydrolysates and its effect on the antioxidant ability of the complexes.

The interaction between cyanidin-3-O-glucoside with casein and casein hydrolysates and its effects on the antioxidant activity of complexes were investigated. Fluorescence spectroscopy results indicated that the interaction between cyanidin-3-O-glucoside and casein was primarily mediated by Van der Waals forces or hydrogen bonds and stronger than the interaction between cyanidin-3-O-glucoside and casein hydrolysates mainly via hydrophobic interaction. Circular dichroism and Fourier-transform infrared spectroscopy analysis showed the secondary structure of casein/casein hydrolysates had a slight change after binding with cyanidin-3-O-glucoside. And larger particles formed due to the protein aggregation induced by the complexation of casein/casein hydrolysates with cyanidin-3-O-glucoside. The antioxidant activity assessments revealed that the synergistic effect was observed in FRAP assay, whereas an antagonistic effect in ABTS assay between casein/casein hydrolysates and cyanidin-3-O-glucoside, which were produced due to the casein/casein hydrolysates-cyanidin-3-O-glucoside interaction. These results would be helpful in designing functional beverages containing anthocyanins and protein hydrolysates with enhanced antioxidant ability.

Effect of milk addition and processing on the antioxidant capacity and phenolic bioaccessibility of coffee by using an in vitro gastrointestinal digestion model.

An in vitro gastrointestinal digestion model was used to investigate the effects of milk matrix: skimmed milk (Sm), whole milk (Wm) and processing methods: pH adjustment, high pressure homogenization processing (HPHP), thermal treatment (TT) on the antioxidant capacity, phenolics bioaccessibility of coffee. Our findings showed that the antioxidant capacity of all the samples decreased or unchanged after in vitro digestion. The total phenolic bioaccessibility of coffee (C), coffee with whole milk (Cwm), and coffee with skimmed milk (Csm) decreased by 29.2%, 28.5%, 21.1% from the HPHP treatment and by 14.7%, 34.2%, and 33.8% from TT, respectively. pH adjustment had little effect on the total phenolic bioaccessibility of Cwm and Csm but significantly decreased that of C. Wm showed better protective effect on the phenolic bioaccessibility than Sm. These results may contribute to the optimization of formulations and processing methods in coffee beverage production, thereby increasing the health benefits of coffee.

Analysis of ß-lactoglobulin-epigallocatechin gallate interactions: the antioxidant capacity and effects of polyphenols under different heating conditions in polyphenolic-protein interactions.

The interaction and antioxidant capacity between epigallocatechin gallate (EGCG) and ß-lactoglobulin (ß-Lg) under thermal treatments at 25-121 °C were investigated in this study. Fluorescence spectroscopy analysis showed that EGCG complexed with ß-Lg mainly via non-covalent interactions and the binding affinity of EGCG to ß-Lg was enhanced with heat treatment. EGCG showed a strong binding affinity to ß-Lg after 85 °C heat treatment was applied, with a Ka of 30.69 (±0.87) × 105 M-1 (pH 6.8, 298 K). Circular dichroism (CD) results showed that heat treatment did not result in greatly affected changes in the ß-Lg secondary structure induced by ß-Lg-EGCG interactions. MALDI-TOF/TOF-MS analysis showed that ß-Lg-EGCG covalent conjugates initially formed after heat was applied at 60 °C, and their proportions increased under heat treatment ranging from 85 to 121 °C. The amino group of a lysine residue was further confirmed as the covalent binding site of EGCG to ß-Lg. The ß-Lg-EGCG interaction showed little effect on the antioxidant capacity (ABTS and ferric reducing antioxidant power (FRAP) values) of EGCG after heat treatment at 25-60 °C, but did induce an obvious reduction at temperatures above 85 °C. This study will provide the foundation for the use of EGCG in processing dairy products (such as milk tea beverages) with desirable nutrition and physiological functions.

Effects of ß-cyclodextrin, whey protein, and soy protein on the thermal and storage stability of anthocyanins obtained from purple-fleshed sweet potatoes.

The effects of ß-cyclodextrin (ß-CD), whey protein (WP), and soy protein (SP) on the color loss and degradation of anthocyanins in purple-fleshed sweet potato anthocyanin extracts (PFSPAEs) during thermal treatment and shelf-life storage in model beverage systems by performing chromaticity, degradation kinetics, and principal component analysis. Results showed that WP and SP improved the thermal stability of the PFSPAE, but WP accelerated the color loss of the extract. However, the addition of 25 mg/L SP improved the color and thermal stability of the anthocyanins when heated at 100 °C for 30 min. With regard to the shelf-life storage, the addition of SP and WP showed non-significant effect on the storage stability of the PFSPAE. However, the addition of 2500 mg/L ß-CD significantly improved the storage stability of the PFSPAE. In summary, our findings provide useful information on improving the thermal and storage stability of PFSPAEs in beverage systems using food biopolymers.