Food Technology
Reza Farahmandfar; Sahar Aboutalebzadeh; Hannaneh Moniri; Massoud Kaykhaii
Abstract
Black tea, which is obtained from the leaves of small tree Camellia sinensis, is a popular drink that has been consumed for centuries all around the world. In this study, a sample of Iranian black tea was brewed by two methods of microwave and traditional brewing and their extracts were then assessed ...
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Black tea, which is obtained from the leaves of small tree Camellia sinensis, is a popular drink that has been consumed for centuries all around the world. In this study, a sample of Iranian black tea was brewed by two methods of microwave and traditional brewing and their extracts were then assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays to determine their phenolic and flavonoid contents as well as heavy metal (HM) (copper, nickel, chromium, cadmium and lead) content. It was observed that there is a direct relationship between the antioxidant activity with their phenolic and flavonoid contents. The highest and lowest antioxidant activities were observed for samples brewed by microwave at 360 W for 2.5 min and 900 W for 7.5 min, respectively. As the brewing power and time increased, the antioxidant activity decreased. Brewing tea by microwave and traditional methods caused a significant reduction in the amount of heavy metals, which was lower than the allowable limit according to the Iranian national standards. These results demonstrate the importance of exposure time and radiation power when tea is prepared by microwave.
Reza Farahmandfar; Somayeh Salmani; Hoda Fahim
Abstract
Introductıon: Nuts are one of the major resources of bioactive compounds such as tocopherols, tocotrienols, sterols (Jensen and Lauridsen, 2007). Tocopherols include 8 natural homologues that all of them belongs to vitamin E group (Chun, 2002). It is well known that vitamin E has good antioxidant activity ...
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Introductıon: Nuts are one of the major resources of bioactive compounds such as tocopherols, tocotrienols, sterols (Jensen and Lauridsen, 2007). Tocopherols include 8 natural homologues that all of them belongs to vitamin E group (Chun, 2002). It is well known that vitamin E has good antioxidant activity and among its isomers, α-tocopherol and γ-tocopherol have highest biological activity and free radical scavenging, respectively (Grilo et al., 2014). In recent years, the beneficial health effects of vitamin E on some disease such as cancer and heart disorders attract researcher’s attentions (Wagner et al., 2004).Roasting process changes the chemical and nutritional properties of nuts, including antioxidants, vitamins, colors, and aroma mostly through Maillard reaction (Alamprese et al., 2009; Ballistreri et al., 2009). Due to the importance of vitamin E antioxidant activity and its heat sensitivity, the residual amounts of them after different roasting conditions were investigated. Materials and methods: Samples were spreaded in alominum foil and placed in forced air oven at 120 and 150 ºC and different time intervals including 0, 20, 30 and 40 min. After roasting, samples were powdered, then 0.5 g of each sample plus 0.05 g ascorbic acid were added to 0.5 mL ethanol (90.2%) and 0.5 mL KOH and mixed in a tube (16× 125 mm). The tube was then placed in water bath for 30 min. Then, the tube were placed in ice bath for 5 min, then 3 mL deionized water, 5 mL hexane were added to the tube and vortexed for 30 s and centrifuged for 10 min at 1000 rad/s at ambient temperature. The extraction was done twice. Hexane layer evaporated with nitrogen then 1 mL of mobile phase added to tube and vortexed again. Prepared samples then were injected to HPLC (Knuer- Germany). Results and discusion: Based on the obtained results, α-tocopherol content in almond was more than γ-tocopherol. After 20 and 30 min of roasting, at 150 and 120 ºC respectively, the amount of α-tocopherol slightly increased, while it decreased with increasing roasting time. γ-tocopherol content in almond at both temperatures also increased up to 20 min roasting and decreased till the end of process. In hazelnut, at both temperatures up to 20 min and then decreased till end of roasting process. This trend was shown for peanut tocopherols as well. With increasing in roasting time, α-tocopherol and γ-tocopherol content decreased to their initial level. It has suggested that tocopherols which attached to the other components such as phospholipids released more conveniently under thermal treatment like roasting which leads to increase their concentrations at initial of thermal process. In pistachio, 150 and 120 ºC respectively caused to increase in γ-tocopherol content, respectively while its content decreased up to the end of roasting time (40 min). α-tocopherol content at both temperatures increased after 20 min, then decreased gradually as time passes. Results indicated that both time and temperature of roasting had a significant effect on α- and γ-tocopherol of four nuts. Although both of temperatures in our study significantly on increased vitamin E isomers at the start of roasting process, their contents decreased with increasing in roasting time. Maximum amount of both isomers were detected at 120 ºC after 30 min and at 150 ºC after 20 min.
Reza Farahmandfar; Maryam Asnaashari; Milad Amraie; Mohammad Salehi
Abstract
The consumer’s acceptance significantly reduces during the storage of fresh cut fruits. Edible coating is one of the most innovative ways to maintain quality and improve shelf life of fresh fruits and vegetables. The objective of this study was to assess the suitability of quince seed gum (QSG) ...
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The consumer’s acceptance significantly reduces during the storage of fresh cut fruits. Edible coating is one of the most innovative ways to maintain quality and improve shelf life of fresh fruits and vegetables. The objective of this study was to assess the suitability of quince seed gum (QSG) at different concentrations (0.5, 1 and 1.5%) as edible coatings for banana slices and to determine their influence on changes in physicochemical properties during storage at 4 °C and 40 °C. Data on shrinkage, weight loss and color were collected and subjected to statistical analysis. Banana slices which coated with 1 % of QSG and stored at 4 °C showed significantly better physicochemical characteristics. Higher temperatures result in more rapid changes of quality parameters. On the other hand, samples coated with gum reduced the weight loss and shrinkage during storage. It is recommended that 1% quince seed gum can be used to reduce the surface fresh-cut banana browning.
Reza Farahmandfar; Reza Safari; Fahimeh Ahmadi Vavsari; Tahmineh Bakhshandeh
Abstract
In this study, effect of Thyme (Thymus vulgaris) ultrasonic extract on the quality of Hypophthalmichthys molitrix surimi was evaluated. For this purpose, the leaves of Thymus vulgaris were dried, grinded and soaked in methanol (1:10 w/v) for 30 min at 45˚C and sonicated at 30 kHz for 15 min at 40˚C. ...
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In this study, effect of Thyme (Thymus vulgaris) ultrasonic extract on the quality of Hypophthalmichthys molitrix surimi was evaluated. For this purpose, the leaves of Thymus vulgaris were dried, grinded and soaked in methanol (1:10 w/v) for 30 min at 45˚C and sonicated at 30 kHz for 15 min at 40˚C. The extract was suspended by Dimethyl sulphoxide and mixed with surimi (0.4 and 0.8% w/w). Then, the analysis of chemical (free fatty acid, peroxide value, Thiobarbituric acid and total volatile base nitrogen) and microbial (mesophilic and psychrotrophic viable count) properties of the samples were done at specific intervals after zero, 4, 8, 12 and 16 days of storage at 2 ºC. Results of chemical and microbial analysis showed that 0.8% concentration of T. vulgaris could increase the shelf life of Hypophthalmichthys molitrix surimi and there is significant difference between control and treated samples. Moreover, the results could be claimed that the T. vulgaris due to marvelous antioxidant and antimicrobial component such as thymol (52.17%), ρ-cymene (14.42%), carvacrol (9.11%) and γ- terpinene (4.45%) has significant effect on preventing the Hypophthalmichthys molitrix surimi oxidation and microbial growth. The results also showed ultrasound was the effective way to extract the Thymus vulgaris beneficial compounds.
Reza Farahmandfar; Seyed Ali Mortazavi; Farideh Tabatabaei Yazdi; Arash Koocheki
Abstract
In this study, variations of the pasting properties, swelling power and solubility of two rice starches, low amylose (8.7%) and high amylose (26%) at two citric acid concentrations (0 and 0.01 M) was investigated. The results showed that the peak viscosity and breakdown viscosity of rice starch decreased ...
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In this study, variations of the pasting properties, swelling power and solubility of two rice starches, low amylose (8.7%) and high amylose (26%) at two citric acid concentrations (0 and 0.01 M) was investigated. The results showed that the peak viscosity and breakdown viscosity of rice starch decreased significantly (P<0.05) with increased the proportion of amylose while hot past viscosity and cold past viscosity increased significantly (P<0.05). As the concentration of citric acid increased, pasting properties decreased but did not change (P>0.05).The swelling power and solubility of both starch pastes with and without citric acid increased with the increase of the temperature. As the concentration of citric acid increased, swelling power of low and high amylose starch decreased and this event was clearer in low amylose samples. On the other hand, citric acid induced solubility of samples particularly in high amylose rice starches. Furthermore, the swelling power and solubility of treatments decreased and increased with increasing amylose content of rice starch, respectively.
