Effect of ultrasound-assisted cold plasma pretreatment on cell wall polysaccharides distribution and extraction of phenolic compounds from hyssop (Hyssopus officinalis L.).

Hyssopus officinalis L (Hyssop) is a good source of phenolic compounds. However, conventional methods for extraction of these compounds typically take a long time and have relatively low recovery rates. This study focused on cold atmospheric plasma (CAP) pretreatment and investigated its effects on the ultrasound-assisted extraction (UAE) of phenolic compounds from hyssop. Hyssop was treated at dielectric barrier discharge plasma with air and nitrogen gases for 5, 10, and 15 min. Optical emission spectroscopy was used to evaluate present active species in the plasma. The water contact angle changes, cell wall polysaccharides distribution, and structural variations of the treated samples were determined after treatment. Antioxidant activity and total phenolic contents (TPC) of the extracts were also evaluated. The results showed that CAP treatment reduced the contact angle making surface more hydrophilic. Compared with hyssop, overall no significant changes in the basic structure of all treated samples or the formation of new functional groups were recognized. In addition, CAP pretreatment before UAE increased the antioxidant activity of extracts according to the FRAP assay than the un-pretreated sample and conventional solvent extraction method. Also, TPC increased in samples treated with nitrogen plasma.

Antioxidant activity of raspberry (Rubus fruticosus) leaves extract and its effect on oxidative stability of sunflower oil.

Efficacy of R. fruticosus leaves extract in stabilizing sunflower oil during accelerated storage has been studied. Extracts of R. fruticosus were prepared in different solvents which methanolic extract yield with 15.43 % was higher than water and acetone ones (11.87 and 6.62 %, respectively). Methanolic extract was chosen to evaluate its thermal stability at 70 °C in sunflower oil, due to the highest yield, antioxidant and antiradical potential and also high content of phenolic compounds campared to other solvents. So, different concentrations of methanolic extract (200, 400, 600, 800 and 1,000 ppm) were added to sunflower oil. BHA and BHT at 200 ppm served as standards besides the control. Peroxide value (PV) and thiobarbituric acid (TBA) were taken as parameters for evaluation of effectiveness of R. fruticosus leaves extract in stabilization of sunflower oil. Moreover, antioxidant activity index (AAI) of the extract at 120 °C at rancimat were conducted. Results from different parameters were in agreement with each other, suggesting the highest efficiency of 1,000 ppm of the extract followed by BHT, BHA and other concentrations of the extract. Results reveal the R. fruticosus leaves extract to be a potent antioxidant for stabilization of sunflower oil.

Dough performance, quality and shelf life of flat bread supplemented with fractions of germinated date seed.

Germinated palm date seeds were milled into two fractions: germ and residue. Dough rheological characteristics, baking (specific volume and sensory evaluation), and textural properties (at first day and during storage for 5 days) were determined in Barbari flat bread. Germ and residue fractions were incorporated at various levels ranged in 0.5-3 g/100 g of wheat flour. Water absorption, arrival time and gelatination temperature were decreased by germ fraction but accompanied by an increasing effect on the mixing tolerance index and degree of softening in most levels. Although improvement in dough stability was monitored but specific volume of bread was not affected by both fractions. Texture analysis of bread samples during 5 days of storage indicated that both fractions of germinated date seeds were able to diminish bread staling. Avrami non-linear regression equation was chosen as useful mathematical model to properly study bread hardening kinetics. In addition, principal component analysis (PCA) allowed discriminating among dough and bread specialties. Partial least squares regression (PLSR) models were applied to determine the relationships between sensory and instrumental data.

Evaluating the potential of natural curcumin for oxidative stability of soybean oil.

The active substance of turmeric rhizome (curcumin) was extracted and identified with TLC and NMR. To evaluate the antioxidant efficiency of different concentrations of curcumin (120, 160 and 200 ppm) compared with tert-butylhydroquinone (TBHQ) (120 ppm) and α-tocopherol (200 ppm) at two different temperatures (25°C and 55°C) under dark and light conditions during 90 days, the soybean oil with no added antioxidant was used as a food model, and its fatty acids profile was determined by GC. Results indicated that increasing concentration of curcumin leads to significantly decreased oxidation rates. The soybean oil containing curcumin at 25°C in darkness with the lowest rate of increased peroxide value indicated the same antioxidant activity with α-tocopherol and TBHQ. Moreover, the results of acid value and iodine value indicated that samples with curcumin were more effective in preventing oxidation at both temperatures compared with control. However, light did not have any significant effect.