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This study aims to evaluate the effect of olive leaf extract (OLE) on growth performance, breast meat quality, antioxidant capacity and caecal microbiota regulation. OLE containing 51.5% oleuropein, 25.6% polyphenols and 6.2% flavonoids, was designed to different supplement levels ranging from 0.1% OLE (OLE0.1) to 0.5% OLE (OLE0.5) into a basal diet, separately. The whole feeding period lasts for 35 days after 7-day hatching from the egg. 720 1-day-age healthy Arbour Acres male broilers were thus divided into five experimental groups and one control group, consist of 20 broilers per group for six parallel experiments in triplicate. The results showed that the levels of average daily feed intake (ADFI) and average daily weight gain (ADG) of the broilers were decreased (p < 0.05) after the addition of 0.3% OLE. Moreover, the breast meat shear force was decreased by 34.4% (p < 0.05). The glutathione (GSH) levels in the meat were increased by 76.64% (p < 0.05); the levels of total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) were increased by 50.4% and 120%, respectively. And the malondialdehyde (MDA) levels in the meat were reduced by 34.2% (p < 0.05). Additionally, a decreased intensity of Escherichia coli (p < 0.05) and an increased intensity of Lactobacillus and Bifidobacterium (p < 0.05) were observed. Overall, supplementing 0.3% OLE into daily diet enables enhancing breast meat antioxidation, amplifying the abundance of Lactobacillus and Bifidobacterium as well as diminishing the abundance of E. coli in the caecum.HIGHLIGHTSOLE contains 51.5% oleuropein, 25.6% of TP and 6.2% TF levels.OLE addition at 0.3% lowers shear force and raises the GSH’s level of the meat.OLE causes a decrease in E. coli and an increase in Lactobacillus and Bifidobacterium. OLE contains 51.5% oleuropein, 25.6% of TP and 6.2% TF levels. OLE addition at 0.3% lowers shear force and raises the GSH’s level of the meat. OLE causes a decrease in E. coli and an increase in Lactobacillus and Bifidobacterium.

Hydroxytyrosol oligomer from bioenzymatic catalysis indicates a pleiotropic wellness improving (e.g. antioxidation, anti-inflammatory and anti-carcinogenesis) than its monomer. However, the processing parameters and the insightful mechanism of hydroxytyrosol polymerization are still lacking. To explore in detail the process of hydroxytyrosol polymerization, the effects of different reaction factors (solvent type, pH value of reaction solution, reaction temperature and time) on the polymerization yield were investigated, and molecular docking was executed to reveal the relevant structural variations of these enzymes. The results showed hydroxytyrosol polymerization implemented by laccase performed the best at 50 °C for 20 min in the aqueous buffer solution of pH 5.0. The docking results demonstrated PRO4, TYR7, ASP8, PRO12, LEU121 and VAL14 in site 9 of laccase interacted with hydroxytyrosol in hydrogen bonding, pi-sigma, pi-alkyl and van der Waals’ force. Moreover, the molecular dynamic results implied their interaction-energy variation reaching balance within 175 ps, which confirmed the enzymes’ structural changes. Meanwhile, structural analysis in torsion and bond lengths showed that the C–O of phenolic bonds from hydroxytyrosol evidently rotated and its length of the relevant O–H became longer when binding to laccase compared with free hydroxytyrosol. All the findings are helpful to strengthen the understanding for the enzymatic polymerization of catechol-based structures and the resulting o-dihydroxy-grafting oligomers could be potentially used in the field of functional foods, cosmetics and pharmaceuticals, even or an innovative bioenzyme design such as biosensor for measuring phenols in industrial effluent or preparing the singular oligomer oriented is worth being explored in future. Communicated by Ramaswamy H. Sarma

Starch has received research focus due to its low cost, excellent film-forming ability, bio-compatibility, extensive sources, renewability and biodegradability. However, native starch with relatively strong hydrophilicity greatly limits its application in industries. Therefore, in this paper, the recent research advances in chemical modifications of starch for hydrophobicity, e.g., esterification, etherification, crosslinking, grafting and condensing reaction etc., were discussed. The changes of hydrophobicity and other properties due to chemical modifications were described, as well. Different applications of modified starch with better hydrophobicity, i.e., packaging industries, Pickering emulsion and pharmaceutical, are presented, too. Finally, the future research and prospects on chemical modifications of starch for hydrophobicity and their applications are proposed.

Purification and structural characterization of a novel polysaccharide fraction from Chaenomeles speciosa seeds were investigated. After hot water extraction and ethanol precipitation, the crude polysaccharide was sequentially purified with Cellulose DEAE-52 and gel-filtration chromatography, and a highly purified polysaccharide fraction (F3) was obtained. The structure of F3 was characterized by high-performance gel permeation chromatography (HPGPC), high performance liquid chromatography (HPLC), ultraviolet-visible (UV), Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectrum, together with methylation, scanning electron microscopy (SEM), atomic force microscope (AFM), and Congo-red test analysis. The results indicated that F3 was a homogeneous polysaccharide fraction with a molecular weight of 8.65 × 106 Da, and it was composed of Rha, GlcA, Gal, and Ara in a molar ratio of 6.34:5.73:47.14:40.13. The backbone of F3 was consisted of →3,6)-Galp-(1→, and the side chains of F3 were composed of Araf-(1→, →4)-GlcpA-(1→, →4)-Galp-(1→ and →3)-Rhap-(1→. The hypoglycemic assays demonstrated F3 had good α-amylase and α-glucosidase inhibition activities, and their IC50 values were 6.24 mg/mL and 4.59 mg/mL respectively. Thus, the polysaccharide from Chaenomeles speciose could be applied as a potential natural source in retarding postprandial hyperglycemia effects.

To reveal the relationship between peel color variation, phenolic content and antioxidant performance during the developmental process of seven Chinese jujubes, the content variation of specific phenolic compounds of these jujube peel extracts were determined. Simultaneously, their jujube peel color values and antioxidant performances were measured by CIE L∗a∗b∗ and, DPPH and the ABTS + scavenging capacity, respectively. The contents of total phenolics and flavonoids, including gallic acid, chlorogenic acid, caffeic acid, coumarin, (+)-catechin, p-coumaric acid, ferulic acid, quercetin, (−)-epicatechin and rutin as well as the DPPH scavenging capacity dramatically increased as the peel color became darker from stage 1 to stage 2, but decreased in stage 3. Interestingly, the ABTS + scavenging capacity of the peel extract declined continuously due to a different action mechanism. All these suggest that the jujube peel color variation can indicate polyphenol content and antioxidant properties in the development period.

Hydroxytyrosol oligomer prepared by bioenzyme shows stronger health-promoting properties than its monomer. However, the polymerization process carried out by laccase, tyrosinase or horseradish peroxidase is still lacking in term of product characterization, kinetics and thermodynamics. To achieve these aspects, ATR-FT-IR, NMR, the Michaelis-Menten equation and isothermal titration calorimetry were explored. The results showed that the identified polymers presented a C C bond and a degree of polymerization less than six. Laccase showed the greatest affinity to hydroxytyrosol via comparison of Km and Vm. All of these polymerization processes were spontaneous and exothermic behaviuors ranging from 30 to 50 °C, and were driven by hydrogen bonds, van der Waals interactions and hydrophobic interactions. Furthermore, circular dichroism spectroscopy was used to reveal the enzymatic structural changes during the catalysis, which showed that β-sheet levels for laccase, α-helix levels for tyrosinase, and the α-helix and random coil levels for horseradish peroxidase were dramatically decreased.

Chinese quince seed proteins were sequentially extracted based on the modified Osborne method. Investigations showed that albumin and glutelin were the major fractions. The physicochemical and functional properties of these two fractions were determined. The results showed that both albumin and glutelin posed appropriate essential amino acid composition and met the minimum recommendation (World Health Organization/Food and Agriculture Organization) for adult diet, except for methionine. The hydrophobicity of albumin and glutelin were 1063.56 and 1170.21, respectively. According to differential scanning calorimeter analysis, the denaturation temperature of albumin and glutelin was 101.44 °C and 108.36 °C respectively, and the glutelin fraction had a better thermal stability. The solubility and apparent viscosity of albumin and glutelin were presented to be greatly influenced by pH values. The water holding capacity and oil adsorption capacity of glutelin were 5.44 g/g and 8.15 g/g, higher than those of albumin which were 3.76 g/g and 3.71 g/g, respectively. Circular dichroism determination revealed albumin and glutelin were mainly composed by α-helix and random coil structures. Albumin and glutelin presented the potential as favorable nutrition and functional additive in food industries.

The hydrolysis of proteins could produce more bioactive moieties. To obtain more bioactivities, Chinese quince seed protein was hydrolyzed by papain to produce biological peptides. After ultrafiltration, gel filtration chromatography, and reversed phase high performance liquid chromatography purifications, two novel peptides were successfully prepared. Matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF-TOF) tandem mass spectrometer was applied to identified the amino acid sequences of these two purified peptides, and they were Asparagine-Tyrosine-Arginine-Arginine-Glutamic acid (NYRRE, 737.059 Da) and Arginine-Histidine-Alanine-Lysine-Phenylalanine (RHAKF, 658.010 Da), respectively. In the antioxidant assays, RHAKF showed stronger DPPH, superoxide anion radicals scavenging activity and lipid peroxidation inhibition than NYRRE. Moreover, RHAKF exhibited better copper chelating activity than NYRRE, as its IC50 value was 0.93 mg/mL and it was lower than that of NYRRE (2.11 mg/mL). The tyrosinase inhibition evaluation demonstrated that RHAKF exhibited much better inhibitory activity than NYRRE. To explain this phenomenon, molecular docking simulation was used to reveal the interactions between tyrosinase and peptides. More docking sites were observed between RHAKF and tyrosinase, and this likely supported the better inhibitory behavior of RHAKF. These findings implied RHAKF would be more appropriate to be applied as potential skin-care agent in pharmaceutic or cosmetic industries.

Chinese quince seed protein isolate (CPI) was extracted using aqueous extraction and the isoelectric precipitation method, and its physicochemical and functional properties were investigated. Results showed that CPI contained all essential amino acids with exception of methionine which met the minimum recommendations for adults (World Health Organization/Food and Agriculture Organization). The electrophoresis analysis of sodium dodecyl sulphate polyacrylamide gel indicated that the molecular weights of protein fractions were approximately 15–60 kDa. Differential scanning calorimetry analysis was conducted, and the denaturation temperature of CPI was 103.4 °C. The surface hydrophobicity of CPI was found to be 932.80. The experiments showed that CPI had high emulsifying capacity, foaming stability, water holding capacity and oil adsorption capacity. Moreover, CPI also had outstanding gel formation capacity since its least gelation concentration of CPI was only 8%. All these results implied that CPI could be a nutritional protein resource and functional ingredient in the food industry.

Three techniques of ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) and solvent extraction (SE) were used for enhancing the hydroxytyrosol (HT), maslinic acid (MA) and oleanolic acid (OA) extraction from olive pomace, being evaluated and compared through process parameters, kinetics and thermodynamics, plus greenness assessment analysis. Results showed that UAE yielded the maximum compounds due to a strong cavitation effect and the strongest mass and heat transfer efficiency involving the kinetic constants (h, Ce and K) and thermodynamic parameters (△H, △S and △G). Additionally, the optimal extraction conditions were acquired: ethanol concentration of 90%, extraction temperature of 50 °C, extraction time of 5 min, liquid to solid ratio of 30 mL/g, ultrasound intensity of 135.6 W/cm2, and ultrasound frequency of 60 kHz. UAE was confirmed as an effective and greener technique with the lowest E factor, energy consumption and carbon emission during the extraction process of bioactive compounds from olive pomace.

The compositions of olive leaf extract (OLE), bound phenolics of olive leaf (BPOL), olive fruit extract (OFE) and bound phenolics of olive fruit (BPOF) were determined by HPLC/UV–vis, and the antioxidant activity was evaluated based on the reducing power and different types of radical scavenging capacities, i.e., DPPH⋅, ⋅OH, ABTS⋅+ and O2⋅−. The comparison of the structural differences in their DPPH⋅ scavenging capacity with FRAP provided insight into the phenolic structure–antioxidant activity relationships. Both OLE and OFE consisted of oleuropeosides, flavones and phenolic acids. Oleuropein was highly concentrated in OLE, where caffeic acid and luteolin were predominant in OFE. OLE exhibited a dose-dependent behavior and high antioxidant ability due to the synergism of its phenolic compounds. Conversely, OFE displayed poor reducing power and antiradical activity, but its superoxide radical scavenging capacity was stronger than that of OLE. Chlorogenic acid dominated in BPOL with an approximately 2-fold amount than that in BPOF. The antioxidant capacity mainly depended on the catechol moiety, the number of hydroxyl groups and a double bond conjugated to the 4-position on the aromatic ring. OLE may therefore be more suitable than OFE as a functional food ingredient due to its stronger antioxidant activity.