M. Majzoobi

ABSTRACT Due to the importance of the role of NaCl in starch-based systems, the effect of NaCl and water content on specific volume, color parameters and moisture loss of cassava and potato starches was studied and response surface methodology was used to find and estimate any nonlinearity between the parameters under study. Glass transition (Tg) is one of the main factors determining the quality parameters of toasted and baked samples. Therefore, Tg of two starch systems (cassava and potato) at low water levels (<20%) as affected by NaCl and water content was investigated. Using experimental modeling, equations were obtained to relate expansion, color change and moisture loss of baked samples to salt level and water content. Differential scanning calorimetry-measured Tg showed that NaCl had negative impact on glass/rubber transition temperature of starch–salt mixtures compared with the samples without NaCl. This could have practical implications in baking, toasting and extrusion processing of starch-based systems.PRACTICAL APPLICATIONDue to concerns over health-related issues of high intake of salt by the consumers, recently, the reduction of salt in different food products has become the focus of many industrial projects, conferences and workshops. In breakfast cereals, other than starch type, other added ingredients such as sugar and salt can have profound effects on the physical characteristics of final products. The inclusion of salt in breakfast cereals has some important technological roles, e.g., structure formation and flavor and color generation. Salt plays a key role in the expansion of low-moisture extruded starch-based products. Using the findings of this paper, one may quantify the effects of salt level on expansion and color of baked, toasted or extruded starch-based cereal products and relate the changes to the glass rubber transition of the system.

ABSTRACT The extraction of Salvia macrosiphon seed hydrocolloid was performed successfully and the optimum hydration time and temperature were found to be 30 min and 25 °C for 12% extraction yield. The effect of solution pH (3–9) and addition of NaCl (0.5–3%), CaCl2 (0.5–3%) and Na2HPO4 (0.2–0.6%) on rheological properties of the hydrocolloid solutions were investigated. Rheologcal data were fitted with the Power law model with regression coefficient of greater than 0.95. Strong shear thinning behavior with the n value of less than 0.53 was recorded. All variables had significant impacts on rheological parameters. The minimum and maximum consistencies were found at pH 3 and the 9, respectively. This was explained with the presence of carboxylic groups on the biopolymer backbone as indicated by FTIR. NaCl, CaCl2 and Na2HPO4 had significant effects on rheological properties. Moreover, at similar salt concentration of 0.5%, Na2HPO4 had the greatest and NaCl had the lowest effect.

ABSTRACT Time and energy consuming centrifugation and purification steps have been reported as the main challenges for isolation of high quality hydrocolloids from mucilaginous seeds in commercial production. Ultrasound-assisted isolation of mucilaginous hydrocolloids from Salvia macrosiphon seeds as an innovative technology was performed successfully. After determination of optimum swelling condition, mucilaginous hydrocolloids samples were isolated using ultrasonic system under different ultrasound conditions (i.e., time, 1-20 min, temperature, 5-60 degrees C and ultrasound power (30-150 W)) and their physicochemical characteristics were studied in terms of yield, lightness, chemical composition, rheological properties and intrinsic viscosity in comparison with the conventional method. Ultrasound method increased yield, lightness and purity, in particular protein content, of the isolated hydrocolloids. Rheological measurements showed that increase of the intensity of ultrasound causes a decrease in consistency coefficient and an increase in the flow behavior index and thus hydrocolloid solutions tend to show more Newtonian behavior. The critical concentrations of S. macrosiphon seed gum isolated with the conventional method and the strongest ultrasonic treatment were 0.06 and 02 g/dl, respectively. Ultrasound showed to be a suitable method to isolate hydrocolloids from S. macrosiphon seeds. Industrial relevance: Isolation of mucilaginous hydrocolloids from seeds is a major challenge for commercializing these promising hydrocolloids. Using power ultrasound, isolation of hydrocolloid from S. macrosiphon mucilaginous seeds was performed, successfully. Ultrasound is able to scrape swelled mucilage layers of the seeds layer by layer. In the conventional method during high shear application some parts of the seed cores are crushed that would require extra separation steps such as high speed centrifugation. However, with ultrasound method seed cores are not broken down, therefore no centrifugation step is needed.

... ACCEPTED MANUSCRIPT 1 Effects of L-Cysteine on some characteristics of wheat starch Mahsa Majzoobi1*, Asgar Farahnaky1, Jalal Jamalian1, Mohsen Radi1 1 Department of Food Science and Technology, School of Agriculture, Shiraz University, Shiraz, Iran. ...

Paramyosin is a muscle protein which is characteristic of all invertebrates but which is not present in vertebrate muscles. Given the functional importance of paramyosin, the purpose of this paper was to study the physico-chemical properties, including the amino acid composition and rheological behaviour, of purified paramyosin and to investigate its mode of interaction with myosin. Paramyosin was purified from the limpet (Patella caerula) by an ethanol precipitation step. It was soluble at ionic strengths below 0.05 M NaCl and its maximum solubility at neutral pH occurred at approximately 0.4 M NaCl. At this high ionic strength, the pH dependence of solubility was such that paramyosin passed quickly into solution when pH exceeded pH 5, the transitional pH value. By using an immunological method, it was shown that interactions between paramyosin and myosin occurred, even in the presence of actin. The molecular assembly of both proteins was probably specified by hydrophobic interactions, as well as by interactions enhanced by divalent cations. The changes in the dynamic shear storage modulus (G') started between 40 degrees C and 50 degrees C, and reached a maximum at about 75 degrees C.