Jirarat Tattiyakul

Extraction and electrospinning of gelatin from fish skin

Ultra-fine gelatin fibers were successfully fabricated by electrospinning from the solutions of Nile tilapia (Oreochromis niloticus) skin-extracted gelatin in either acetic acid or formic acid aqueous solutions. The extracted gelatin contained 7.3% moisture, 89.4% protein, 0.3% lipid, and 0.4% ash contents (on the basis of wet weight), while the bloom gel strength, the shear viscosity, and the pH values were 328 g, 17.8 mPa s, and 5.0, respectively. Both the acid concentration and the concentration of the gelatin solutions strongly influenced the properties of the as-prepared solutions and the obtained gelatin fibers. At low acid concentrations (i.e., 15% (w/v) extracted gelatin solutions in 10 and 20% (v/v) acetic acid solvents or 10-60% (v/v) formic acid solvents), a combination between smooth and beaded fibers was observed. At low concentrations of the gelatin solutions in either 40% (v/v) acetic acid solvent or 80% (v/v) formic acid solvent (i.e., 5-11%, w/v), either discrete beads or beaded fibers were obtained, while, at higher concentrations (i.e., 14-29%, w/v), only smooth or a combination of smooth and beaded fibers were obtained. The average diameters of the obtained fibers, regardless of the types of the acid solvents used, ranged between 109 and 761 nm. Lastly, cross-linking of the obtained gelatin fiber mats with glutaraldehyde vapor caused slight shrinkage from their original dimension, and the cross-linked gelatin fiber mats became stiffer.

Morphology, Release Characteristics, and Antimicrobial Effect of Nisin-Loaded Electrospun Gelatin Fiber Mat

Gelatin electrospun (e-spun) fiber mats containing nisin were produced by electrostatic spinning of gelatin-nisin in 70% (vol/vol) acetic acid aqueous solutions. Varying nisin loading concentration (0 to 3% [wt/wt]) did not affect the fiber average diameter, whereas increasing gelatin concentration from 20 to 24% (wt/vol) caused an increase in the average diameter. All nisin-loaded gelatin e-spun fiber mats demonstrated inhibition against Lactobacillus plantarum TISTR 850. However, all fiber mats were fragile and easily dissolved in water. Cross-linking by saturated glutaraldehyde vapor at 37 degrees C for 5 min was done to strengthen the mat. Tensile strength, Youngs modulus, and elongation of the cross-linked gelatin-nisin e-spun fiber mats varied in the range of 2.6 to 20.3 MPa, 163 to 966 MPa, and 1.7 to 5.9% , respectively. Cross-linking did not affect the mats inhibition activity against L. plantarum TISTR 850. Nisin retention in cross-linked antimicrobial gelatin e-spun fiber mats was in the range of 1.0 to 1.22% . Increasing temperature caused an increase in nisin release, but increasing water activity did not cause a significant difference in nisin release over 50 h. After storage at 25 degrees C for 5 months, the antimicrobial gelatin e-spun fiber mat still showed inhibition against L. plantarum TISTR 850. The mats also inhibited the growth of Staphylococcus aureus and Listeria monocytogenes but not Salmonella Typhimurium.

Heat transfer to a canned corn starch dispersion under intermittent agitation

Abstract A thermorheological model for the heating a 3.5% corn starch dispersion (STD) was used together with a finite element based simulation software (FIDAP) to solve the governing mass, momentum and energy transport equations for heating the STD at 121 °C in a 303×406 axially rotating can. Heat transfer from the hot wall to the inner canned STD improved considerably in intermittent rotation because the boundary layer region was not covered with a thick layer of gelatinized starch. In comparison to the experimental data obtained in a Steritort™, the simulated time–temperature profile was conservative and was in reasonable agreement. Further, simulation results showed that increase in the retort temperature results in a higher relative volume average temperature. In contrast, increase in the reel rotational speed in the 5–12 rpm range brought about a reduction in the volume average temperature.

Effect of Hydroxypropyl Methylcellulose on Rheological Properties, Coating Pickup, and Oil Content of Rice Flour-Based Batters

Rice flour-based batter is an alternative for wheat flour-based batter for consumers with wheat allergy or wheat intolerance. Further advantage of rice flour in batter is its ability to reduce oil uptake. However, due to its low-protein content, high amylose, and small granule size, rice flour-based batter possesses poor adhesion property. The aim of this study was to investigate the effect of the addition of hydroxypropyl methylcellulose (HPMC); a hydrocolloid, on rheological properties, coating pickup, and oil absorption of HPMC-rice-based fried batter. Rheological properties of rice flour-based batters containing HPMC with different degrees of substitution (DS) and concentrations were determined. In steady-shear measurements, the addition of HPMC; E4M (DS = 1.9) and K4M (DS = 1.4), led to the increase of apparent viscosity, yield stress, and consistency index. K4M rice flour batters showed shear-thickening behavior (n > 1) with syneresis. HPMC increased the complex modulus (G*) of batters, where storage moduli (G′) were higher than loss moduli (G″). The crossover points increased with increasing HPMC concentration. HPMC addition increased the coating pickup of fresh carrot sticks and less coating loss was observed with K4M. Rice batter formulated with 0.5% E4M provided deep-fried crust with 26% lower oil content compared to the control crust.

Effects of High‐Pressure Processing on Inactivation of Salmonella Typhimurium, Eating Quality, and Microstructure of Raw Chicken Breast Fillets

UNLABELLED High-pressure inactivation of Salmonella Typhimurium DMST 28913, eating quality, and microstructure of pressurized raw chicken breast meat was determined. The inoculated samples (approximately 7 log CFU/g initial load) were processed at 300 and 400 MPa, using pressurized medium of 25 to 35 °C during pressurization. Weibull model was well fitted to the survival curves with tailing. Least severe conditions with acceptable inactivation levels were 300 MPa, 35 °C, 1 min (approximately 2 log reduction) and 400 MPa, 30 °C, 1 min (approximately 4 log reduction). Based on these 2 conditions, the 400 MPa treatment yielded the raw chicken meat with higher L* value, greater cooking loss, and lower water holding capacity. Cooked chicken breast meat prepared from the pressurized samples had firmer texture than the control. Scanning electron microscopic images showed that higher pressure resulted in increasing extent of protein coagulation and the contraction of the muscle bundles. PRACTICAL APPLICATION For raw chicken breast fillet, 300 MPa, 35 °C, 1 min was the condition that reasonably reduced the load of Salmonella Typhimurium. However, the pressurized samples had greater cooking loss. Marination with brine containing sodium chloride and phosphate prior to pressurization might help improve this eating quality.

Isolation and Rheological Properties of Tamarind Seed Polysaccharide from Tamarind Kernel Powder Using Protease Enzyme and High-Intensity Ultrasound

The effectiveness of using protease and combinations of protease and high-intensity ultrasound for high-purity, high-yield tamarind seed polysaccharide (TSP) production was investigated. Tamarind kernel powder (TKP) suspension was treated with protease alone at 0.16, 0.48, and 0.80 units/mL and with protease-ultrasound combinations over 3 different orders of sequence (before, simultaneous with, and after protease digestion) using combinations of 0.48 units/mL protease and high-intensity ultrasound at 25% and 50% amplitude for 15 and 30 min. The long protease digestion time could produce high-purity isolated TSP, but the polysaccharide yields were lower. The polysaccharide purity and yield were highly improved, even at a shorter protease digestion time, when the protease treatment was combined with high-intensity ultrasound. The increased amplitude level and sonication time decreased the average molecular weight of the polysaccharide. The rheological properties of the TKP and the isolated TSP, from nondestructive oscillatory measurements, demonstrated that the latter present a viscoelastic solution. The decreasing of protein content resulted in better elasticity of the solution. The power law model could be used to fit the down curve between shear rate and shear stress data. The consistency coefficient (K) increased while the flow behavior index decreased with the increased purity of the polysaccharide as a result of increasing increased digestion time, enzyme concentration, sonication power, and sonication time.

Role of structure in the measurement of flow properties of food and starch dispersions: a review.

In this review, briefly the role of structure of food dispersions in their rheological properties and how it affects rheological measurement are discussed. Besides processed food dispersions, starch dispersions during and after gelatinization are considered. The discussion points out to the benefit of studying rheological properties of dispersions with known composition and structural characteristics. Lastly, we discuss frequency shift factor for superposing the temperature and shear dependent viscosity data during gelatinization of starch dispersions to obtain master viscosity curves.

Biaxial Extensional Viscosity of Sheeted Noodle Dough

ABSTRACT The flows encountered during the sheeting process contain a more extensional component and more stretching than simple shear. Evaluating the properties of the extensional rheological flow of wheat flour dough is essential to better understand the sheeting process and the final quality of the product. Our results show that the curves of biaxial extensional viscosity versus extensional strain rate for dough from different wheat cultivars including Dark Northern Spring (DNS), Hard Red Winter (HRW), and Western White Wheat (WW) with protein contents of 7.81–18.09% and water contents of 32–40% could be discriminated. During a lubricated compression test, the sheeted dough displayed a region of extensional thickening followed by a region of mild extensional thinning, giving rise to an s-shaped extensional stress-strain rate curve. The higher degree of extensional thinning was exhibited for the sheeted dough prepared from the flour of DNS and HRW wheat mixture with an extensional thinning index of n = 0...

Rheological behavior of heated starch dispersions

Publisher Summary Starch is a major source of calories and raw materials in food and process industries. In foods, starch is majorly used as as a thickening/gelling agent. The swelling of starch granules is not hindered at low starch (excess moisture) concentrations. Gelatinized starch dispersions (STDs) may also be viewed as microgel systems, whose flow and viscoelastic behavior are strongly influenced by the physical state of granules (size and size distribution). The state of the starch granule influences whether heated starch dispersion exhibits shear-thinning, shear-thickening, or antithixotropic rheological behavior. Increase in volume fraction of starch granules beyond a threshold imparts yield stress to the dispersions. Dynamic rheological data obtained during gelatinization reflect in part the changes in granule volume fraction as a result of corresponding changes in a granule size.