Yukio Kakuda

Polyphenolics in Grape Seeds—Biochemistry and Functionality

Grape seeds are waste products of the winery and grape juice industry. These seeds contain lipid, protein, carbohydrates, and 5-8% polyphenols depending on the variety. Polyphenols in grape seeds are mainly flavonoids, including gallic acid, the monomeric flavan-3-ols catechin, epicatechin, gallocatechin, epigallocatechin, and epicatechin 3-O-gallate, and procyanidin dimers, trimers, and more highly polymerized procyanidins. Grape seed extract is known as a powerful antioxidant that protects the body from premature aging, disease, and decay. Grape seeds contains mainly phenols such as proanthocyanidins (oligomeric proanthocyanidins). Scientific studies have shown that the antioxidant power of proanthocyanidins is 20 times greater than vitamin E and 50 times greater than vitamin C. Extensive research suggests that grape seed extract is beneficial in many areas of health because of its antioxidant effect to bond with collagen, promoting youthful skin, cell health, elasticity, and flexibility. Other studies have shown that proanthocyanidins help to protect the body from sun damage, to improve vision, to improve flexibility in joints, arteries, and body tissues such as the heart, and to improve blood circulation by strengthening capillaries, arteries, and veins. The most abundant phenolic compounds isolated from grape seed are catechins, epicatechin, procyanidin, and some dimers and trimers.

Lycopene degradation and isomerization in tomato dehydration

Lycopene is an important nutrient, since it appears to provide protection against a broad range of epithelial cancers. Tomatoes and tomato products are the major source of lycopene, and are considered to be an important source of carotenoids in the human diet. Biodegradation of lycopene not only affects the attractive color of the final products, but also their nutritive value. The main cause of lycopene degradation in tomato dehydration is isomerization and oxidation. The objectives of this study were to determine the retention of total lycopene and isomerization in different dehydration methods, and to optimize processing technology for the retention of lycopene biological potency in the tomato products. Experiments were carried out to compare the effect of osmotic treatment, vacuum-drying, air-drying and their combination on the retention of lycopene bioactivity. Firstly a skin treatment was applied to the tomatoes, following an osmotic treatment at 25°C in 65°Brix sucrose solution for 4 h, then vacuum-drying at 55°C for 4–8 h, or air-drying at 95°C for 6–10 h. In the fresh tomato samples, lycopene content is 75.5 μg/100 g on dry weight basis. Lycopene occurs in nature primarily in the more stable all-trans form. A significant increase in the cis-isomers with simultaneous decrease in the all-trans isomers can be observed in the dehydrated tomato samples in the different dehydration methods. The cis-isomers increased with temperature and processing time. In the osmotic treatment, the predominating mechanism is isomerization of lycopene. Since the total lycopene content remained essentially constant, but the distribution of trans- and cis-isomers changed. In the air-drying processing, isomerization and oxidation (autoxidation) as two strong factors affected simultaneously the decrease of total lycopene content, distribution of trans-and cis-isomers, and biological potency. A possible explanation of this result is that sugar enters the tomato matrix and strengthen the binding force on lycopene in the tomato matrix. Osmotic solution (sugar) remaining on the surface layer of the tomato prevents oxygen from penetrating and oxidizing lycopene. The osmotic treatment could reduce lycopene losses in comparison with other dehydration methods.

Purification and identification of antioxidant peptides from grass carp muscle hydrolysates by consecutive chromatography and electrospray ionization-mass spectrometry

Grass carp muscles were hydrolyzed with various proteases (papain, bovine pancreatin 6.0, bromelain, neutrase 1.5MG and alcalase 2.4L) to extract antioxidant peptides. The hydrolysates were assessed using methods of hydroxyl radical scavenging ability and lipid peroxidation inhibition activity. Hydrolysate prepared with alcalase 2.4L was found to have the highest antioxidant activity. It was purified using ultrafiltration and consecutive chromatographic methods including ion-exchange chromatography, multilayer coil high-speed counter-current chromatography, and gel filtration chromatography. The purified peptide, as a potent antioxidant, was identified as Pro-Ser-Lys-Tyr-Glu-Pro-Phe-Val (966.3Da) using RP-HPLC connected on-line to an electrospray ionization mass spectrometry. As well, it was found that basic peptides had greater capacity to scavenge hydroxyl radical than acidic or neutral peptides and that hydrophobic peptides contributed more to the antioxidant activities of hydrolysates than the hydrophilic peptides. In addition, the amino acid sequence of the peptide might play an important role on its antioxidant activity.

Saponins from edible legumes: chemistry, processing, and health benefits.

Demand for bean products is growing because of the presence of several health-promoting components in edible bean products such as saponins. Saponins are naturally occurring compounds that are widely distributed in all cells of legume plants. Saponins, which derive their name from their ability to form stable, soaplike foams in aqueous solutions, constitute a complex and chemically diverse group of compounds. In chemical terms, saponins contain a carbohydrate moiety attached to a triterpenoid or steroids. Saponins are attracting considerable interest as a result of their diverse properties, both deleterious and beneficial. Clinical studies have suggested that these health-promoting components, saponins, affect the immune system in ways that help to protect the human body against cancers, and also lower cholesterol levels. Saponins decrease blood lipids, lower cancer risks, and lower blood glucose response. A high saponin diet can be used in the inhibition of dental caries and platelet aggregation, in the treatment of hypercalciuria in humans, and as an antidote against acute lead poisoning. In epidemiological studies, saponins have been shown to have an inverse relationship with the incidence of renal stones. Thermal processing such as canning is the typical method to process beans. This study reviews the effect of thermal processing on the characteristics and stability of saponins in canned bean products. Saponins are thermal sensitive. During soaking and blanching, portions of saponins are dissolved in water and lost in the soaking, washing, and blanching liquors. An optimum thermal process can increase the stability and maintain the saponins in canned bean products, which is useful for assisting the food industry to improve thermal processing technology and enhance bean product quality.

Extraction of Polyphenolics from Plant Material for Functional Foods—Engineering and Technology

Polyphenolic substances or polyphenols include many classes of compounds ranging from phenolic acids, colored anthocyanins, simple flavonoids, and complex flavonoids. Polyphenolics contribute to the bitterness and astringency of fruits and fruit juices due to the interaction between polyphenolics, mainly procyanidins, and the glycoproteins in saliva. Polyphenols contribute largely to cellular processes within the body. In terms of pharmacological activity, they act against the oxidation of high-density lipoproteins (HDLs). Hence, they help the body retain important HDL while helping it get rid of problematic low-density lipoproteins (LDLs). In addition, polyphenols have also been found to have antiulcer, anticarcinogenic, and antimutagenic activities. The reason behind these activities is polyphenols strong antioxidant power because they are able to quench free radicals. Green tea and grape seed extracts provide a superior source of monomers that are relatively inexpensive to extract. Comparatively, pine bark and other fruits extracts have low levels of monomers. Therefore, the nutraceutical industry has focused on optimizing extraction processes for green tea leaves and grape pomace, skins, and seeds. During extraction, a solvent is mixed with the plant material (grape seeds, grape skins, pine bark, or tea leaves). Extraction can be either completed by the addition of a solvent to the sample in a container and then removed by drying, or the solvent can be removed by concentration by ultrafiltration (UF). After any one of these processes, the extract must be dried to obtain a powder form. Alternatively, supercritical fluid extraction (SFE) can also be used, which produces the final product as a powder without any use of final drying. Organic solvent extraction is efficient and simple, yet costly. Large amounts of organic solvents are needed. This, in turn, is also detrimental to human use because traces of the organic solvent are present in the polyphenol extract. Polyphenol separation and concentration by membrane separation is even more efficient than organic solvent extraction. Organic solvents are still used but in lower quantities, and UF ensures the purity of the polyphenol extract. The drawback is membrane fouling, which can disrupt the process, and the time it takes to complete the process. The separation process has to be repeated several times. Supercritical fluid extraction is the extraction process of the future. CO2 is low cost, nontoxic, nonflammable, and noncorrosive, making it the perfect solvent for natural products. In the U.S. market, where

Synergistic, additive, and antagonistic effects of food mixtures on total antioxidant capacities.

141 million was spent on grape seed products in 1999, it is imperative that safe and efficient extraction procedures are delivered that guarantee a pure polyphenol product.

Electrospun Zein Fibers as Carriers to Stabilize (−)-Epigallocatechin Gallate

Different foods possess different bioactive compounds with varied antioxidant capacities. When foods are consumed together, the total antioxidant capacity of food mixtures may be modified via synergistic, additive, or antagonistic interactions among these components, which may in turn alter their physiological impacts. The main objective of this study was to investigate these interactions and identify any synergistic combinations. Eleven foods from three categories, including fruits (raspberry, blackberry, and apple), vegetables (broccoli, tomato, mushroom, and purple cauliflower), and legumes (soybean, adzuki bean, red kidney bean, and black bean) were combined in pairs. Four assays (total phenolic content, ferric reducing antioxidant power, 2,2-diphenyl-1-picrylhydrazyl, radical scavenging capacity, and oxygen radical absorbance capacity) were used to evaluate the antioxidant capacities of individual foods and their combinations. The results indicated that within the same food category, 13, 68, and 21% of the combinations produced synergistic, additive, and antagonistic interactions, respectively, while the combinations produced 21, 54, and 25% synergistic, additive, and antagonistic effects, respectively, across food categories. Combining specific foods across categories (e.g., fruit and legume) was more likely to result in synergistic antioxidant capacity than combinations within a food group. Combining raspberry and adzuki bean extracts demonstrated synergistic interactions in all four chemical-based assays. Compositional changes did not seem to have occurred in the mixture. Results in this study suggest the importance of strategically selecting foods or diets to maximum synergisms as well as to minimum antagonisms in antioxidant activity.

Salt-soluble seed globulins of various dicotyledonous and monocotyledonous plants—I. Isolation/purification and characterization

In this study, a method was developed for continuous electrospinning of ultrafine corn zein protein fibers with diameters ranging from 150 to 600 nm. Fiber-forming solutions with various zein concentrations (10% to 30%, w/w) and aqueous ethanol concentrations (60% to 90%, w/w) were electrospun at 15 and 20 kV. Scanning electron microscopy results showed that the morphology of zein fibers was affected by aqueous ethanol concentration, zein concentration, and the applied voltage. The optimal condition for forming bead-less fibers was found to be 20% protein, 70% alcohol, and 15 kV. The zein fibers resisted solubilization in water, although swelling and plasticization were apparent after the water treatment. The efficacy of zein fibers was tested for stabilization of a green tea polyphenol, (-)-epigallocatechin gallate (EGCG), by incorporating the EGCG in zein fiber-forming solutions. Freshly spun fibers were less effective at immobilizing the EGCG upon immersion in water (82% recovery) as compared to fibers that were aged at 0% relative humidity for at least 1 d (>98% recovery) before water immersion. Fourier transform infrared spectroscopy studies demonstrated that hydrogen bonding, hydrophobic interactions, and physical encapsulation are the major contributors to the stabilization of EGCG in zein fibers in water.

Salt-soluble seed globulins of dicotyledonous and monocotyledonous plants II. Structural characterization

Abstract Detailed characterization of 21 purified seed globulins derived from both monocotyledonous and dicotyledonous plants indicated that globulins from both class types (as well as within the same class type) lay within a narrow molecular weight range between 300000 and 370000 Da and were composed of multiple subunits. In all cases, purified globulins could be classified as hetero-oligomers being composed of a non-equimolar ratio of various subunits. The vast majority of subunits forming these globulins were shown to be held together by non-covalent bond forces. A small percentage of linkages between subunits were also shown to be disulfide linked, in the case of dicotyledonous seed globulins. It was also found that the majority of subunits composing the dicotyledonous and monocotyledonous seed globulins examined fell within two very narrow molecular weight ranges, i.e. 20000–27000 and 30000–39000 Da and were believed to correspond to basic and acidic subunits, respectively. Unlike monocotyledonous seed globulins, globulins derived from dicotyledonous plants were found to undergo alkaline-induced dissociation due to electrostatic repulsion between subunits. The amino acid composition of both dicotyledonous and monocotyledonous seed globulins suggests that they have a storage role and may be similar proteins based on a high content of amides (glutamic acids-glutamine and aspartic acid-asparagine and arginine). From the results of the structural and chemical data obtained in this study, it is concluded that the 11S storage globulin, having several similar properties, exists in many leguminous and non-leguminous dicotyledonous plants as well as monocotyledonous plants. This similarity among 11S storage globulins could be due either to convergent evolution in response to a common functional need, or to common ancestry.

Stability of all-trans-β-carotene under ultrasound treatment in a model system: Effects of different factors, kinetics and newly formed compounds

Abstract Structural characterization of 21 seed globulins from monocotyledonous and dicotyledonous plants revealed that they generally possessed low levels of α-helix and high levels of β-sheet secondary structure fractions. This finding suggested that the interior conformation of these globulins was very similar. In contrast to internal conformations, tertiary conformations indicated that very distinct surface properties existed between these two globulin classes. It now appears that surface properties are the most variable physico-chemical properties measured between globulins. Calorimetric analysis revealed that both classes of globulins possessed temperatures of denaturation (Td) which were in the temperature range of 83.8 to 107.8 °C. Although dicotyledonous seed globulins had more pronounced thermal transitions than their monocotyledonous counterparts, most endothermic transitions occurred as co-operative events indicating that the various domains present in these globulins were held together by interdependent structural domains. These interdependent domains rendered the globulins stable to high temperatures and in connection with previous data (Marcone and Yada, 1998), it was believed that both monocotyledonous and dicotyledonous seed globulins share similar structural domains.