Inhibition of hemoglobin-mediated oxidation of regular and lipid-fortified washed cod mince by a white grape dietary fiber

Cross-processing herring and salmon co-products with agricultural and marine side-streams or seaweeds produces protein isolates more stable towards lipid oxidation

Herring and salmon filleting co-products were pH-shift processed together with seven antioxidant-containing raw materials ("helpers") including lingonberry-, apple-, oat-, barley- and shrimp-co-products, and two seaweeds (Saccharina latissima, Ulva fenestrata) to produce protein isolates stable towards lipid oxidation. Malondialdehyde (MDA) and 4-hydroxy-(E)-2-hexenal (HHE) levels revealed that all helpers, except shrimp shells, to different extents retarded lipid oxidation both during pH-shift-processing and ice storage. The three helpers performing best were: lingonberry press-cake > apple pomace ∼ Ulva. Color of protein isolates was affected by helper-derived pigments (e.g., anthocyanins, carotenoids, chlorophyll) and lipid oxidation-induced changes (e.g., metHb-formation, pigment-bleaching). In conclusion, combining fish co-products with other food side-streams or seaweeds during pH-shift processing appears a promising new tool to minimize lipid oxidation of protein isolates, both during their production and subsequent storage. Lingonberry press-cake was the most efficient helper but provided dark color which may narrow product development possibilities, something which requires further attention.

Chemical Composition and Functional Properties of Dietary Fibre Concentrates from Winemaking By-Products: Skins, Stems and Lees

The objective of this study was to evaluate, from a technological and nutritional point of view, the chemical composition and functional properties of the industrial winemaking by-products, namely skins, stems and lees. The chemical and physical characteristics, as well as the functional properties (fat and water retention and swelling capacity, antioxidant capacity, and their prebiotic effect), of the dietary fibre of these by-products were studied. The results showed that the skins, stems, and lees are rich in fibre, with the stem fibre containing the highest amounts of non-extractable polyphenols attached to polysaccharides with high antioxidant activity and prebiotic effect. Lee fibre had the highest water retention capacity and oil retention capacity. The results reveal that winemaking by-products could be used as a source of dietary fibre with functional characteristics for food applications.

Improving the Stability of Red Blood Cells in Rainbow Trout (Oncorhynchus mykiss) and Herring (Clupea harengus): Potential Solutions for Post-mortem Fish Handling to Minimize Lipid Oxidation

This study aimed at limiting hemolysis of fish red blood cells (RBCs) as a strategy to limit hemoglobin (Hb)-induced lipid oxidation during post-mortem handling and processing. Effects of varying temperature, salinity, and mechanical impact were studied using washed resuspended RBCs (wr-RBCs) and whole blood (WB) from rainbow trout (Oncorhynchus mykiss) and herring (Clupea harengus). The wr-RBCs were most stable avoiding mechanical stress, keeping isotonic conditions (0.9–1.3% NaCl) and low temperature 0–6 °C, with predicted minimum at 2.5 °C. When compared at the same salinity, it was found that hemolysis was more pronounced in herring than trout wr-RBCs. Furthermore, WB was more stable than wr-RBCs, showing protecting the effects of blood plasma. Studying individual plasma components, stabilizing effects were found from glucose, proteins, and ascorbic acid. This study indicates that small adjustments in the early handling and processing of fish such as changing salinity of storage and rinsing solutions could minimize Hb contamination of the fish muscle and thereby improve quality.

Towards integral utilization of grape pomace from winemaking process: A review

Grape is the main fruit crop in several countries. Although many grape-based food products can be found in the market, studies have shown that around 75% of the world grape production is destined for the wine industry. Grape pomace is an abundant by-product from the wine industry, which consists of the remaining skin, seeds and stalks and represents around 25% of total grape weight used in the winemaking process. In countries such as Italy, France and Spain, where wine production is more relevant, the annual grape pomace generation can reach nearly 1200 tonnes per year. In order to reach a sustainable winemaking process there is a need of a waste reduction policy. Several studies explore this subject using grape pomace as a source of healthy and technological compounds that could be applied in animal feed, pharmaceutical, cosmetic or food industry to improve stability and nutritional characteristics, and in cosmetic industry, where grape seeds oil is widely used. This review aims to approach the recent winemaking scenario and the benefits achieved when a waste management policy is implemented, as well as to compare available extractive technologies and a wide alternative of uses for grape pomace.

Applications of Wine Pomace in the Food Industry: Approaches and Functions

Winemaking generates large amounts of wine pomace, also called grape pomace. This by-product has attracted the attention of food scientists and the food industry, due to its high content in nutrients and bioactive compounds. This review mainly focuses on the different published approaches to the use of wine pomace and its functions in the food industry. Traditionally, wine pomace has been used to obtain wine alcohol, food colorings, and grape seed oil. More recently, research has focused in the production of other value-added products, such as extracts of bioactive compounds, mainly phenols, recovery of tartaric acid, and the making of flours. The most common functions associated with wine pomace products are their use as antioxidants, followed by their use as fortifying, coloring, and antimicrobial agents. These products have mainly been applied to the preparation of meat and fish products and to, a lesser extent, cereal products.

Phenolic profile and in vitro antioxidant capacity of insoluble dietary fiber powders from citrus (Citrus junos Sieb. ex Tanaka) pomace as affected by ultrafine grinding

The effects of mechanical and jet grindings on the proximate composition, phenolics, and antioxidant capacity of insoluble antioxidant dietary fiber powder from citrus pomace (IADFP-CP) were investigated in comparison with ordinary grinding. IADFP-CP from jet grinding showed higher levels of crude fat, total sugar, and free phenolics and lower levels of crude protein and bound phenolics than that from ordinary grinding. Totally, 14 phenolics (9 free, 1 bound, and 4 free/bound) in IADFP-CP were identified by RP-HPLC-DAD/ESI-Q-TOF-MS/MS. Hesperidin accounted for >57% of total phenolics in IADFP-CP. Among IADFP-CPs, the jet-ground presented the highest free phenolics but the lowest bound phenolics. The IADFP-CP from jet grinding presented the highest antioxidant capacity of free phenolics (by DPPH and FRAP assays), followed by the ones from mechanical and then ordinary grinding. The present study suggests that jet grinding could improve the extraction of phenolic compounds from IADFP-CP and increase the antioxidant capacities of free phenolics and the resultant powder.

Effect of caffeic acid on haemoglobin-mediated lipid and protein oxidation in washed cod mince during ice and frozen storage

BACKGROUND

Little is known about the relation between haemoglobin (Hb)-mediated lipid and protein oxidation in muscle foods and how these two reactions can be inhibited by naturally occurring antioxidants. This study was aimed at evaluating (1) lipid oxidation and protein oxidation induced by 20 µmol L(-1) Hb during chilled and frozen storage of washed cod mince and (2) the efficiency of 10-1000 ppm (0.063-6.3 mmol L(-1)) caffeic acid in preventing these reactions.

RESULTS

Addition of 20 µmol L(-1) Hb increased peroxide value (PV), rancid odour, protein carbonylation, protein insolubilisation, redness loss and α-tocopherol loss in ice-stored washed cod mince. Since both lipid and protein oxidation developed at the same time, it was not possible to conclude which reaction initiated the other. All studied reactions were efficiently inhibited by ≥ 50 ppm caffeic acid, which could be a result of α-tocopherol regeneration, general radical scavenging, reduced formation of oxidised Hb forms and/or conformational changes in Hb structure. During frozen storage the only clear effect of Hb was increased PV, and here caffeic acid was less efficient as an antioxidant.

CONCLUSION

Hb-induced lipid and protein oxidation occurred quickly in ice-stored washed cod mince, and the two reactions could not be separated in time. During frozen storage, Hb caused only limited lipid oxidation. Caffeic acid (≥50 ppm) was an efficient antioxidant during ice storage.

Structure-activity relationships of polyphenols to prevent lipid oxidation in pelagic fish muscle

The influence of polymerization (number of monomers) and galloylation (content of esterified gallates) of oligomeric catechins (proanthocyanidins) on their effectiveness to prevent lipid oxidation in pelagic fish muscle was evaluated. Non-galloylated oligomers of catechin with diverse mean polymerization (1.9-3.4 monomeric units) were extracted from pine (Pinus pinaster) bark. Homologous fractions with galloylation ranging from 0.25 to <1 gallate group per molecule were obtained from grape (Vitis vinifera) and witch hazel (Hamamelis virginiana). The results showed the convenience of proanthocyanidins with medium size (2-3 monomeric units) and low galloylation degree (0.15-0.25 gallate group/molecule) to inhibit lipid oxidation in pelagic fish muscle. These optimal structural characteristics of proanthocyanidins were similar to those lately reported in fish oil-in-water emulsions using phosphatidylcholine as emulsifier. This finding suggests that the antioxidant behavior of polyphenols in muscle-based foods can be mimicked in emulsions prepared with phospholipids as emulsifier agents. The present data give relevant information to achieve an optimum use of polyphenols in pelagic fish muscle.

Biological activities of polyphenols from grapes

The dietary consumption of grape and its products is associated with a lower incidence of degenerative diseases such as cardiovascular disease and certain types of cancers. Most recent interest has focused on the bioactive phenolic compounds in grape. Anthocyanins, flavanols, flavonols and resveratrol are the most important grape polyphenols because they possess many biological activities, such as antioxidant, cardioprotective, anticancer, anti-inflammation, antiaging and antimicrobial properties. This review summarizes current knowledge on the bioactivities of grape phenolics. The extraction, isolation and identification methods of polyphenols from grape as well as their bioavailability and potential toxicity also are included.