نشریه پژوهش های علوم و صنایع غذایی ایران
سال سیزدهم شماره 3 (پیاپی 45، امرداد و شهریور 1396)

Identification of a new source of hydrocolloids is of interest due to their important effects on the textural attributes of food products. The objective of this study was to investigate the extraction conditions of Plantago major L. seed mucilage using a central composite rotatable design of response surface methodology. Temperature (25–85°C), pH (3–9) and water to seed ratio (50:1-50:4) were the factors investigated. Results showed that temperature was major factor in the extraction yield, whereas water to seed ratio and pH had minor effects on the yield. The maximum and minimum yields were 18.95% (conditions: temperature= 85 °C, water to seed ratio = 31.3 and pH= 6) and 6.35% (conditions: temperature = 25 °C, water to seed ratio= 31.3 and pH= 6), respectively. The optimal conditions were obtained at the temperature of 60 °C, water to seed ratio of 48.9 and pH of 3 in which predicted value for the extraction yield was 11.84%. The rheological properties of the mucilage, extracted at the optimal conditions, were investigated as a function of concentration at three levels of 3, 4 and 5% w/v, and shear rate ranged from 14 to 300s-1. Mucilage dispersions showed non-Newtonian shear-thinning behavior at all studied concentrations. The Power law model well described the rheological behavior of the mucilage solutions with high determination coefficients (R2>0.99). The flow behavior index (n) varied in the range of 0.30 to 0.36. The consistency coefficient (k) was in the range 6.13-17.81 Pa.sn. Overall, Plantago major L. seed mucilage could be attended as a new beneficial source for use as a food thickening agent.

The acidified ethanol extracts of dried barberry which have a relatively high anthocyanin content (376.28± 1.45 mg c3g/Kg dmp) were freeze dried using maltodextrin (MDX), polyvinyl-pyrrolidone (PVP) and mixture of MDX and calcium alginate (MDX-CaAlg) as a carrier and coating agents. The qualitative attributes of the powders were characterized by their productively encapsulation efficiency, moisture content, bulk density, colour values (L*, a*, b*, C and H° ), particle size, total phenolic compounds (TPC), free radical scavenging activity of DPPH (RSA), ferric reducing-antioxidant power (FRAP) and minimized 50% of radical- scavenging activity (IC50). Scanning electron microscope was used for monitoring the structures of the powders. To determine the stability and half- life period of microencapsulated pigments, samples were stored under different storage temperatures (4◦C and 25◦C) at relative humidity 75%. Results showed that the encapsulated powder containing PVP 8% as wall material represented the best powder quality (p

Methanol, ethanol, acetone and water extracts of Indian Frankincense (Boswellia serrata) were evaluated for their total phenolic contents and antioxidant properties using various methods including 2,2-diphenyl-1picrylhydrazyl, iron (III) reducing power, total antioxidant capacity and oxidative stability index (Rancimat). The four extracts showed varying degrees of antioxidant activity in a dose - dependent manner in each assay. Methanol extract containing the highest amount of phenolic compounds exhibited the strongest antioxidant capacity in all the assays used. Moreover, all the extracts were able to improve the oxidative stability of soybean oil as evaluated by the Rancimat test. On the basis of the results obtained, B. serrata oleo-gum resin was found to serve as a potential source of natural antioxidants due to their considerable antioxidant activity.

The effects of mixed coating based on aloe vera (AG) and gum tragacanth (GT) on the microbial, physicochemical and sensorial properties of fresh strawberries were evaluated during 20 days of storage (1 oC, 95 % RH) compared to uncoated fruits. The coating solutions were prepared by mixing solution of AG diluted 1:3 with distilled water and GT solution (0.6 % w/v in distilled water) at different concentrations (25 % AG % GT, 50 % AG % GT and 75 % AG % GT). Microbial stability (fungi (yeasts and molds) and total aerobic bacteria), physiochemical characteristics (ascorbic acid (AA), weight loss, firmness, titratable acidity, soluble solid content (SSC), anthocyanin content, total phenolic and antioxidant activity) and sensory attributes (color, taste, odor and overall) of the samples were evaluated after 0, 4, 8, 12, 16 and 20 days of storage compared to uncoated fruits. Comparing with untreated fruits, 50 % AG % GT treatment significantly (p

The present study investigated the thermal properties of canola pods (thermal conductivity, specific heat, and thermal diffusivity), canola losses (natural losses, platform losses, and total combine harvester losses), and unbroken pods in three common canola varieties cultivated in the North of Iran (Hyola 420, Hyola 401, and Hyola 50) at three times of pre-harvest, harvest, and post-harvest. Furthermore, the relation between the thermal properties of canola pods and the amounts of losses during harvest was studied. Thermal conductivity coefficient, specific heat, and thermal diffusivity were determined using line heat source, mixture method, and calculation methods, respectively. Seed losses were calculated, using a built grain collector. The results revealed that adjustments, variety, and sampling time had significant effects on thermal conductivity and specific heat of canola varieties at the probability level of 1%. The effect of the interaction between variety and time on thermal conductivity, specific heat, and thermal diffusivity was considerable at the probability levels of 1% and 5%, respectively. Furthermore, the effects of canola varieties and harvest time on natural losses, total combine harvester losses, as well as unbroken pods were substantial at 1% probability. In addition, a notable relation was observed between thermal conductivity coefficient and platform losses at 5% and unbroken pods at 1%. However, unbroken pods indicated a substantial relation with specific heat and thermal diffusivity at 1%.

In this study, the compositional, rheological, thermal and textural properties of omega-3 cow's butter (OCB), conventional cow's butter (CCB) and sheep’s butter (SB) were evaluated. The fatty acid composition of SB showed a relatively high content of the short chain fatty acids (SCFA) compared with that of cow's butters and higher levels of CLA and omega 3 fatty acids in OCB were observed. Regarding to the firmness, at refrigeration temperature (5 °C), SB was much firmer than CCB and OCB, but as a function of temperature, it was softened much quicker. However, at temperatures around 18°C it was already softer than the latter. From dynamic rheological data, it was found that butter samples display solid-like viscoelastic behavior since the values of G ׳ were much higher than those of G″ with a low dependence on frequency. The values of G ׳ and G″ also decreased in butters containing more percentage of unsaturated fatty acids. The temperature effect on the viscosity followed an Arrhenius-type relationship and OCB had a less activation energy than others, indicating that the butter containing high SCFA was more sensitive to temperature changes. Through differential scanning calorimetery, the thermal behavior of the butters during melting was analyzed.