Binding characteristics of polyphenols as milk plasmin inhibitors.

BACKGROUND: The potential use of polyphenols to improve the functional characteristics of dairy products has gained much attention. However, the effects of the polyphenols on naturally occurring enzymes in milk have not been studied extensively. Excess plasmin activity in dairy products might result in several quality defects. The objective of this study was to assess the ability of polyphenols to inhibit plasmin in milk using a molecular and kinetic approach. RESULTS: Epicatechin gallate (ECG), epigallocatechin gallate (EGCG), quercetin (QUER), and myricetin (MYR) caused a significant decrease in plasmin activity by 60, 86, 65, and 90%, respectively. The inhibition rates were alleviated in the presence of milk proteins. EGCG, QUER, and MYR, exhibited noncompetitive inhibition against plasmin, whereas ECG caused a mixed-type inhibition. A decrease in the random structure of plasmin upon the complex formation with ECG, EGCG, QUER, and MYR was found. The other phenolics that were evaluated did not cause any significant changes in plasmin conformation. The observed inhibitory phenolic-plasmin interactions were dominated by H-bonds and electrostatic attractions. Green tea extract (GTE) rich in catechins also inhibited plasmin activity in the milk. CONCLUSION: Significant changes in the secondary structure of plasmin upon binding of ECG, EGCG, QUER, and MYR led to diminished plasmin activity both in the absence and presence of milk proteins. These flavonoids with promising plasmin inhibitory potential could be used in new dairy formulations leading to controlled undesired consequences of plasmin activity. © 2019 Society of Chemical Industry.

Which is the best grape seed additive for frankfurters: extract, oil or flour?

BACKGROUND: Grape seed products (winery by-products) are valuable vegetable sources to enhance the quality of meat products. In this study, 21 treatments of frankfurters, in three different groups, including 0%, 0.01%, 0.03%, 0.05%, 0.1%, 0.3% and 0.5% grape seed extract (GSE), 0%, 1%, 2%, 4%, 6%, 8% and 10% grape seed oil (GSO), and 0%, 0.5%, 1%, 2%, 3%, 4% and 5% grape seed flour (GSF) were produced in order to compare the differences among them during refrigerated storage for 90 days. RESULTS: Increasing the level of GSO made the frankfurters lighter in color (P < 0.05). Lipid oxidation of all the 21 frankfurters were under the limit of deterioration (2.0 mg malonaldehite kg⁻¹ treatment) during 90 days' storage. However, increasing the amount of additives (GSE, GSO and GSF) led to a decrease in overall acceptability for each group. According to the general comparison of the three frankfurter groups in terms of lipid oxidation, TBARS (thiobarbituric acid reactive substances) values of the frankfurters including GSE and GSF were found to be similar, but the frankfurters containing GSO exhibited the highest lipid oxidation (P < 0.05). While the products including GSE were the most acceptable group in terms of overall acceptability, the group produced with GSF received the lowest points (P < 0.05). CONCLUSION: Although the three grape seed products have partially undesirable effects on the sensory characteristics of the frankfurters, all these additives showed different positive influences in the production of frankfurters. The results showed that the group of frankfurters including GSE was the best of three different groups of products due to the lipid oxidation and overall acceptability results.

Grape seed flour is a viable ingredient to improve the nutritional profile and reduce lipid oxidation of frankfurters.

In this study, grape seed flour (GSF) obtained from wine by-products was incorporated into frankfurters at seven concentrations (0, 0.5, 1, 2, 3, 4, and 5%) and the effects occurred on physical, nutritional and sensory characteristics of the products were investigated. The colour values (L*, a* and b*) of frankfurters generally decreased (p < 0.05) on account of the increasing amount of GSF. The utilization of this flour also led to a decline in the oxidation level of the products (p < 0.05), probably due to its antioxidant content. The increment of GSF in the frankfurters enhanced the protein, total dietary fibre and water holding capacity of the treatments (p < 0.05). Although the level of GSF above 0.5% reduced overall acceptability, the frankfurters containing the level up to 2% received scores above the average. The evaluation of wine by-products in the production of healthier and functional frankfurters has been achieved by the study, but further research is necessary to improve palatability of the products.

Fatty acid, triacylglycerol, phytosterol, and tocopherol variations in kernel oil of Malatya apricots from Turkey.

The fatty acid, sn-2 fatty acid, triacyglycerol (TAG), tocopherol, and phytosterol compositions of kernel oils obtained from nine apricot varieties grown in the Malatya region of Turkey were determined ( P<0.05). The names of the apricot varieties were Alyanak (ALY), Cataloglu (CAT), Cöloglu (COL), Hacihaliloglu (HAC), Hacikiz (HKI), Hasanbey (HSB), Kabaasi (KAB), Soganci (SOG), and Tokaloglu (TOK). The total oil contents of apricot kernels ranged from 40.23 to 53.19%. Oleic acid contributed 70.83% to the total fatty acids, followed by linoleic (21.96%), palmitic (4.92%), and stearic (1.21%) acids. The s n-2 position is mainly occupied with oleic acid (63.54%), linoleic acid (35.0%), and palmitic acid (0.96%). Eight TAG species were identified: LLL, OLL, PLL, OOL+POL, OOO+POO, and SOO (where P, palmitoyl; S, stearoyl; O, oleoyl; and L, linoleoyl), among which mainly OOO+POO contributed to 48.64% of the total, followed by OOL+POL at 32.63% and OLL at 14.33%. Four tocopherol and six phytosterol isomers were identified and quantified; among these, gamma-tocopherol (475.11 mg/kg of oil) and beta-sitosterol (273.67 mg/100 g of oil) were predominant. Principal component analysis (PCA) was applied to the data from lipid components of apricot kernel oil in order to explore the distribution of the apricot variety according to their kernel's lipid components. PCA separated some varieties including ALY, COL, KAB, CAT, SOG, and HSB in one group and varieties TOK, HAC, and HKI in another group based on their lipid components of apricot kernel oil. So, in the present study, PCA was found to be a powerful tool for classification of the samples.

Effects of incorporation of interesterified plant oils on quality and fatty acid composition of Turkish-type salami.

Application of interesterified plant oils (IPOs) prepared from palm, cottonseed and olive oil (IPaO, ICO and IOO, respectively) have been studied in Turkish-type salamis. Beef fat (10%) was replaced by one of the IPOs for 20, 60 or 100%. Incorporation of IPO was well reflected in fatty acid composition and saturated fatty acids/unsaturated fatty acids (SFA/UFA) ratios of the lipid fraction of all batches. Significant differences in appearance, color, texture, flavour or total score were not found among the control and Turkish-type salamis with different types and levels of IPO. We conclude that IPOs may be successfully applied as beef fat substitutes in Turkish-type salami.