Taha M. Rababah

Optimization of Extraction Conditions of Total Phenolics, Antioxidant Activities, and Anthocyanin of Oregano, Thyme, Terebinth, and Pomegranate

The purpose of this study was to evaluate the total phenolic extracts and antioxidant activity and anthocyanins of varieties of the investigated plants. These plants include oregano, thyme, terebinth, and pomegranate. The optimum extraction conditions including temperature and solvent of the extraction process itself were investigated. Total phenolic and anthocyanin extracts were examined according to Folin-Ciocalteu assay and Rabino and Mancinelli method, respectively. The effect of different extracting solvents and temperatures on extracts of phenolic compounds and anthocyanins were studied. Plant samples were evaluated for their antioxidant chemical activity by 2, 2-diphenyl-1-picrylhydrazl assay, to determine their potential as a source of natural antioxidant. Results showed that all tested plants exhibited appreciable amounts of phenolic compounds. The methanolic extract (60 °C) of sour pomegranate peel contained the highest phenolic extract (4952.4 mg/100 g of dry weight). Terebinth green seed had the lowest phenolic extract (599.4 mg/100 g of dry weight). Anthocyanins ranged between 3.5 (terebinth red seed) and 0.2 mg/100 g of dry material (thyme). Significant effect of different extracting solvents and temperatures on total phenolics and anthocyanin extracts were found. The methanol and 60 °C of extraction conditions found to be the best for extracting phenolic compounds. The distilled water and 60 °C extraction conditions found to be the best for extracting anthocyanin.

Antioxidant activities, total phenolics and HPLC analyses of the phenolic compounds of extracts from common Mediterranean plants

In this study, the total phenolic amounts and antioxidant activities of plant extracts obtained from some common Mediterranean plant species collected from different places in Jordan were determined. The phenolic constituents of these extracts were also determined using HPLC. The total phenolic amounts ranged from 52.8 to 876.9 mg GAE per 100 g dry material. The antioxidant activities were evaluated according to the 2,2-diphenyl-1-picrylhydrazyl radical scavenger method. Sage (Salvia officinalis) showed the highest antioxidant activity (91%), while the lowest (11.3%) was seen in parsley (Petroselinum crispum). A strong correlation (r  =  0.85) between antioxidant activity and total phenolic content was found. The phenolic compounds identified by HPLC were gallic acid, protocatechuic acid, catechin, gentisic acid, chlorogenic acid, vanillic acid, syringic acid, caffeic acid, epicatechin and benzoic acid. All the investigated plants contain gallic acid, whose phenolic content ranged from 0.4 to 37.8 mg per 100 g, catechin (0.3–339.9 mg per 100 g), protocatechuic acid (0.3–41.9 mg per 100 g) and gentisic acid (0.3–35.8 mg per 100 g), while caffeic acid (0.3–2.6 mg per 100 g) was detected in six species only. These natural plant phenolics could thus be a good source of antioxidants for applications in food.

Total Phenolics, Antioxidant Activities, and Anthocyanins of Different Grape Seed Cultivars Grown in Jordan

The total phenolics, antioxidant activities, anthocyanins, vitamine E, and tert-butylhydroxytoluene (BHT) of different cultivars of grape seed extracts (GSE) grown in Jordan were evaluated. In addition, antioxidant activities of GSE were investigated using olive oil substrate by oxidative stability instrument (OSI). Results of chemical composition showed that Baladi black and Asbani black had the highest amount of fat content 14.52 and 14.22 g /100 g seed, respectively, followed by Baladi green (13.28 g /100 g seed), Ajloni green (12.24 g/100 g seed), and Khudari green (10.92 g/100 g seed), respectively. The total phenolics and anthocyanins of GSE ranged from 4.66 to 5.12 g/100 g extracts and 0.14 to 0.68 g/100 g extracts, respectively. Antioxidant activities of GSE ranged from 66.4 to 81.40%, while vitamin E and BHT were 90.34 and 94.70%, respectively. Antioxidant activity of the extracts using OSI ranged from 3.10 to 41.13 h induction time, while vitamin E and BHT had 16.33 and 17.20 h, respectively. GSE had high amounts of antioxidants and can be used to retard lipid oxidation in a variety of food products.

Effect of Barley Flour on Quality of Balady Bread

Balady bread was prepared from barley flour (Rum and ACSAD 176 flour) with local wheat flour (Unified and Zero flour). Chemical, physical, and sensory analysis of the bread was performed. The results showed that there were variations in physical and chemical properties, between different barley varieties, barley flour, and the bread. This study showed that barley flour can be mixed with wheat flour to provide Balady bread that is acceptable to the consumer by 15 and 30%. Additional portions of barley flour resulted in harder bread, darker color, non uniform-shaped loaf, and unacceptable quality for the consumer. The results also showed a better quality of unified wheat flour compared to Zero wheat flour, which was mixed with barley flours; Rum and ACSAD 176 produced a better overall bread quality that was acceptable to the consumers.

Effects of Green Tea and Grape Seed and TBHQ on Physicochemical Properties of Baladi Goat Meats

The effect of natural extracts of green tea or commercial grape seed in combination with synthetic tert methyl-butylhydroquinone at different concentrations on lipid oxidation and the redness of goat meats stored at 5°C for 9 days was evaluated. Fresh boneless Baladi goat meats were ground and mixed at varying concentrations of green tea or grape seed extract alone or combined with tert methyl-butylhydroquinone. The color values of raw goat meat and the thiobarbituric acid-reactive substance values of raw and cooked goat meats were determined following 0, 3, 6, and 9 days of storage at 5°C. The antioxidant activity of the plant extracts and the tert methyl-butylhydroquinone ranged from 4.6–10.2 h induction time using an oxidative stability instrument. Thiobarbituric acid-reactive substance values ranged from 0.21 to 1.21 and 0.31 to 4.57 mg malondialdehyde/kg (goat meat) for the raw and cooked goat meats, respectively. Tert methyl-butylhydroquinone and plant extracts significantly decreased lipid oxidation of the goat meats, with a higher level of addition being more effective in minimizing lipid oxidation. Grape seed extract significantly increased the redness, while green tea extract decreased it; no effect of tert methyl-butylhydroquinone on the redness of goat meats was observed. This study has shown that inclusion of natural extracts of green tea and grape seed in goat meat could reduce lipid oxidation during its storage.

Quality Attributes of Halva by Utilization of Proteins, Non-hydrogenated Palm Oil, Emulsifiers, Gum Arabic, Sucrose, and Calcium Chloride

Emulsion stability (oil separation) in halva is a major problem that affects quality upon storage. Emulsion instability results in toughness, oil separation, and oil contamination on packaging materials. The objective of this study was to evaluate the effectiveness of improving halva quality by incorporating non-hydrogenated palm oil, glycerol, soy protein concentrate, gelatin, lecithin, pectin, gum Arabic, sugar powder, and calcium chloride. Halva was produced by heating sugar (sucrose) solution (65%) containing citric acid (0.65%) and heating to reach 105° C, adding halva root (Saponaria officinalis) extract solution (5.6%) and continuing heating for 60–70 min. This is followed with cooling at room temperature for 15 min and adding tahinia (sesame paste) (1:1) and mixing for 10 min. The additives to improve the quality of halva were incorporated with the sugar solution, during cooking, and with tahinia. The quality of halva was evaluated by measuring the amount of oil separation, microscopic examination, and oil viscosity. Microscopic examination of halva showed a porous non-crystalline sugar melt particles surrounded by a precipitated protein layer originating from tahinia. The oil was found as free non-emulsified fluid, filling in the spaces between solid particles. The saponin (from halva root extract) possibly precipitated the colloidal proteins of tahinia, and contributed to a fragile structure. Soy protein concentrate, gelatin, glycerol, and lecithin incorporation did not improve emulsion stability. However, calcium chloride, sugar powder, gum Arabic, and pectin minimized emulsion instability. Furthermore, 1.0% or 2.5% of non-hydrogenated palm oil increased viscosity of the oil phase and contributed to emulsion stability.

Modifying the physicochemical properties of pea protein by pH-shifting and ultrasound combined treatments

The effect of a pH-shifting and ultrasound combined process on the functional properties and structure of pea protein isolate (PPI) was investigated. PPI dispersions were adjusted to pH 2, 4, 10, or 12, treated by power ultrasound for 5min, and incubated for 1h before the sample pH was brought back to neutral. After treatment, water solubility, protein aggregate size, solution turbidity, surface hydrophobicity (Ho), free sulfhydryl content (SH), and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of the soluble PPI were determined. pH-shifting at pH 12 and ultrasound combined treatment (pH12-US) significantly improved protein properties, while property modification of the samples treated under acidic conditions was less pronounced. The pH12-US treated PPI had a solubility seven times higher than the control, reaching an average particle size of 45.2nm. In addition, the pH12-US treated PPI significantly improved Ho due to disulfide bonds disruption, and produced more protein sub-units than other treatments. The soluble PPI obtained through this process may be a promising emulsifier for the enrichment of fat-soluble nutrients in foods.

Nonthermal Inactivation of Soy (Glycine Max Sp.) Lipoxygenase by Pulsed Ultraviolet Light

This study investigated pulsed ultraviolet (PUV) illumination at different distances from the PUV source on soybean lipoxygenase (LOX) (0.4 mg/mL in 0.01 M Tris-HCl buffer, pH 9) activity. Samples (5 mL) were illuminated for 1, 2, 4, 8, and 16 s at 3 distances 6, 8.5, and 11 cm from the PUV lamps quartz window. The temperature of 33.5 ± 1.8°C was observed for the highest treatment time of 16 s at the shortest distance of 6 cm, and resulted in a 3.5 log reduction (99.95%) in initial LOX activity. Illumination time and distance from the lamp significantly (P ≤ 0.05) affected LOX inactivation. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was performed on treated LOX samples and further protein profile for treated LOX filtrate (≤10 kDa), was analyzed by reverse phase high-performance liquid chromatography (RP-HPLC). The protein profile analysis revealed that LOX protein degradation was influenced significantly (P ≤ 0.05) by PUV illumination time.

In Vitro Gastric and Intestinal Digestions of Pulsed Light-Treated Shrimp Extracts

Pulsed ultraviolet light (PUV), a novel technology most commonly used for microbial inactivation, has recently been employed to effectively mitigate food allergens in peanuts, soybean, shrimp, and almond. Putative mechanisms for the efficacy of PUV in reducing allergen reactivity include photothermal, photochemical, and photophysical effects. To date, there are no published data highlighting the effects of in vitro simulated gastric and intestinal digestion on the stability of PUV reduced allergen reactivity of food. In this study, PUV-treated shrimp extracts were subjected to simulated gastric fluid containing pepsin and simulated intestinal fluid containing trypsin and chymotrypsin, and then tested for changes in allergen potency. SDS-PAGE showed no major band deviation between undigested and digested PUV-treated shrimp extracts. IgE binding to tropomyosin remained markedly decreased as seen in Western blot analysis. Total shrimp allergen reactivity remained unchanged following in vitro peptic digestion and was markedly reduced following in vitro intestinal digestion as illustrated in indirect ELISA. The PUV reduced shrimp allergens remained at a low level under the in vitro simulated digestive conditions. The results inferred that PUV could be a potential method to create less allergenic shrimp products that would remain at a low allergen level under human gastric and intestinal digestive conditions.

Shelf life extension of roasted peanuts by surface lipid removal

Removal of lipids on the surface or from a layer adjacent to the surface of a roasted peanut kernel was investigated as a means to extend the oxidative stability or shelf life of roasted peanuts. Georgia green runner-type peanut kernels were roasted at 178°C in an electric oven for 15 min. Roasted peanuts were subjected to lipid extraction in hexane by mechanical shaking and sonication at room temperature for various durations. Peanut oil was recovered from hexane using a Soxtec lipid extraction system. The surface conditions of the peanuts before and after lipid removal were examined using a florescence microscope. Results showed that surface lipids of the roasted peanuts used in this study existed at a level of approximately 0.56% of the total peanut mass. Florescence micrographs revealed that the surface of sonicated peanut kernels was clean and almost free of oil stains, as opposed to that of freshly roasted peanut kernels, where a considerable amount of lipids remained on the surface of roasted peanuts. Statistical analysis indicated that lipid removal could significantly improve the oxidative stability of roasted peanuts, and it was possible to extend the shelf life of roasted peanuts by removing partial lipids from the roasted peanuts. The results also showed that power ultrasound could remove the lipids more effectively than mechanical shaking.