A suitable vehicle for integration of bioactive plant constituents is proposed. It involves modification of proteins using phenolics and applying these for protection of labile constituents. It dissects the noncovalent and covalent interactions of β-lactoglobulin with coffee-specific phenolics. Alkaline and polyphenol oxidase modulated covalent reactions were compared. Tryptic digestion combined with MALDI-TOF-MS provided tentative allocation of the modification type and site in the protein, and an in silico modeling of modified β-lactoglobulin is proposed. The modification delivers proteins with enhanced antioxidative properties. Changed structural properties and differences in solubility, surface hydrophobicity, and emulsification were observed. The polyphenol oxidase modulated reaction provides a modified β-lactoglobulin with a high antioxidative power, is thermally more stable, requires less energy to unfold, and, when emulsified with lutein esters, exhibits their higher stability against UV light. Thus, adaptation of this modification provides an innovative approach for functionalizing proteins and their uses in the food industry.

This study addresses the interactions of coffee storage proteins with coffee-specific phenolic compounds. Protein profiles of Coffea arabica and Coffea canephora (var. robusta) were compared. Major phenolic compounds were extracted and analyzed with appropriate methods. The polyphenol-protein interactions during protein extraction have been addressed by different analytical setups [reversed-phase high-performance liquid chromatography (RP-HPLC), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS), and Trolox equivalent antioxidant capacity (TEAC) assays], with focus directed toward identification of covalent adduct formation. The results indicate that C. arabica proteins are more susceptible to these interactions and the polyphenol oxidase activity seems to be a crucial factor for the formation of these addition products. A tentative allocation of the modification type and site in the protein has been attempted. Thus, the first available in silico modeling of modified coffee proteins is reported. The extent of these modifications may contribute to the structure and function of "coffee melanoidins" and are discussed in the context of coffee flavor formation.

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The covalent interactions between whey protein isolate (WPI) and rosmarinic acid (RosA) at two different conditions, alkaline (pH 9) and enzymatic (in the presence of tyrosinase, PPO), at room temperature with free atmospheric air were studied. The conjugates formed between WPI and RosA were characterized in terms of their physicochemical and functional properties. The changes in protein structure were analyzed by intrinsic fluorescence and binding of 8-anilino-1-naphthalenesulfonic acid. The findings show that the covalent interactions caused a decrease in free amino and thiol groups and tryptophan content at both conditions. The decrease at enzymatic conditions was lower than at alkaline conditions. In addition, modified WPI at alkaline conditions exhibited higher antioxidative capacity compared to the modification at enzymatic conditions. However, WPI modified at enzymatic condition showed mild antimicrobial activity against Staphylococcus aureus LMG 10147 and MU50 compared to WPI modified at alkaline conditions and unmodified WPI (control). The modified WPI can be used as multifunctional ingredient into various food products with an additional health promoting effect of the bound phenolic compounds.

Farmers in rural areas of almost all the districts of Bangladesh cultivate different varieties of edible plant karela to satisfy nutritional requirements. Herein, we report on the characteristics of seed oils and nutrients and mineral contents of seeds from three varieties of karela. Most of the physicochemical characteristics were significantly (P < 0.05) affected with the samples tested. Seed oils of all varieties displayed a higher degree of unsaturation and in GLC reported herein, only five fatty acids were identified. The profiles of fatty acid composition were not wholly similar in all varieties in which unsaturated fatty acids represented more than 72%, α-eleostearic acid having been detected in the amount of 50.36-53.22%. Acylglycerol classes were estimated to be monoacylglycerols (1.18-2.01%), diacylglycerols (1.83-2.98%), and triacylglycerols (91.11-93.03%) whereas lipid classes included neutral lipids (86.83-91.09%), glycolipids (4.37-7.43%), and phospholipids (3.22-4.62%). Of the major energy producing nutrients, all varieties contained large amounts of lipid (33.93-36.21%) and protein (18.23-21.36%), and potentially useful amounts of calcium (383.45-440.96 µg/g), iron (41.10-45.03 µg/g), and other essential minerals. The nutrient information presented in this report should stimulate the local public health authorities in Bangladesh to consider the question of recommending the vegetable karela to be consumed by adults and children alike in Bangladesh, including pregnant women and others with higher than normal nutritional requirements.

Protein play an important role in determining structure and texture of various food products. Therefore, the goals of this research were to study the functional properties of faba bean protein cultivar, Giza3, compared to ß-Lactoglobulin (ß-Lg) and to hydrolyze this protein using pepsin at different pH values (1.5 and 3) and different incubation periods (0, 5, 10, 60, and 180 min) to characterize the resultant hydrolysates and evaluate their antioxidant activities. The solubility at different pH, emulsifying properties, stability against creaming and oil droplets size, of faba bean protein were tested compared to ß-Lg protein. The findings cleared that the solubility and emulsifying properties of faba protein were very low compared to ß-Lg. Concerning to hydrolysis process, the degree of hydrolysis at pH 1.5 was higher than that at pH 3. The molecular weight distribution bands of faba protein hydrolysates were in the range of 9-98 kDa using SDS-PAGE method while, peptides were in the range of 500 -4000 Da using MALDI-TOF MS method. The results of both methods confirmed that the hydrolysis at pH 1.5 was higher than pH 3. Moreover, the enzymatic hydrolysis significantly improved the antioxidant activity of faba bean protein. Hydrolysates produced at pH 3 had a slight high antioxidant activity than at pH 1.5 at all incubation periods. Finally, these results suggest that faba bean hydrolysates could be used in preparing functional foods and as natural antioxidants to prevent oxidation process in food products.

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Although, the covalent modification of proteins with phenolic compounds has currently found great efforts, applications of these proteins are rare. Therefore, this study was planned to characterize the whey protein isolate (WP) modified with chlorogenic acid (CA) and rosmarinic acid (RA), at pH 9 in the presence of air and at room temperature. The modified protein was evaluated as antioxidant and antiviral agent to inhibit Tobacco mosaic virus (TMV) on infected tomato plants. The WP proteins were characterized using the change in the intensity of tryptophan fluorescence and UV-Vis spectra of proteins, RP-HPLC, ultra-high-performance liquid chromatography coupled with electrospray ionization-quadrupole-time of flight-mass spectrometry (UHPLC-ESI-Q-TOF-MS) and TEAC assay. The results showed that the maximal tryptophan fluorescence intensity of modified proteins, WP-CA and WP-RA, were significantly decreased by 54.71 % and 82.61%, respectively. Data of ESI-MS illustrated that one or more molecules of CA and RA covalently bound to WP. Moreover, the WP modified with RA showed better antioxidant activity when compared with the unmodified WP and WP modified with CA. The antiviral results indicated that plants treated with WP, WP-CA and WP-RA had a decreased number of local lesions and virus concentration over the controls. Quantitative real-time PCR analysis revealed that the expression levels of defense related genes, PR1 and phenylalanine-ammonia lyase (PAL) were significantly increased in treated tomato plants compared to the control. These results indicate that the modified proteins could be used to design a wide range of food products and at the same time improve the antiviral activity against TMV, which seriously harms the tomato crop and thus the manufacture of its products.