RESUMEN
In this study, a pH-sensitive indicator based on fish gelatin and Coleus scutellarioides anthocyanin extract (CSAE) was prepared and characterized. Films were prepared using the solvent casting method and different levels of CSAE, including 10 ml (CSG1), 20 ml (CSG2), and 30 ml (CSG3), and 0 ml (CSG0) as a control sample. The mechanical, optical, and pH sensing of active films and the release of anthocyanins from the films were investigated. The relationship between the total volatile basic nitrogen (TVB-N) of fish fillets and a* color index of films was studied. By incorporation of CSAE, the flexibility of films increased, while the tensile strength and UV-Vis light transmittance through the films decreased (p < .05). The films containing the CSAE had a darker, yellowish, and reddish color than the control film. There was a significant relationship between the pH variation and the film color. The films had a purple color at acidic pH, and their color changed to green at an alkaline pH, indicating the sensitivity of the produced films to pH changes. There was a significant relationship between the TVB-N value of fish fillets and the a* index of the film during the 16 h storage time. The results showed that by increasing TVB-N values of the fillets, the a* color index decreased, and the films' color changed from purple to colorless. In summary, the active films prepared with fish gelatin and CSAE could be used as pH-sensitive intelligent packaging to display the freshness of fishery products.
RESUMEN
The aim of this study was to investigate the effects of dual modification on the functional, microstructural, and thermal properties of tapioca starch. Tapioca starch was first hydrolyzed by 0.14 M HCl for 0, 6, 12, 18, and 24 hr and then hydroxypropylated by adding 0%, 10%, 20%, and 30% (v/w) propylene oxide. The degree of hydroxypropylation, solubility, water absorption, rheological, thermal, and microstructure characterization of dually modified tapioca starch was determined. Hydroxypropylation did not cause any considerable changes in the starch granular size and shape of tapioca starch. Acid hydrolysis disrupts the starch granules, and the starches with smaller sizes were produced. The degree of molar substitution (DS) of dual modified starches ranged from 0.118 to 0.270. The dual modified starches significantly had higher solubility than native starch (p < .05). Hydrolysis of starches with acid decreases swelling power while hydroxypropylation increases the swelling power. The results also showed lower gelatinization (To, Tp, Tc, and ΔH) and pasting parameters (the peak and final viscosity, peak time, and pasting temperature) for the dual modified starches than other treatments. In summary, this study showed that dually modified tapioca starch has potential application in dip molding and coating.
RESUMEN
This study investigates the influence of 24-hr marination (with different plant extracts and vinegar) at refrigerated conditions on commonly evaluated physicochemical and textural attributes, including pH, water-holding capacity (WHC), collagen solubility, moisture, drip loss, and shear force values of beef meat. The results reflected the appropriate correlation between each pair and indicated the efficiency of the household marination procedure to acquire more palatability and tender beef meat. Therefore, to predict beef meat tenderness by applying the Warner-Bratzler shear force (WBSF), a strong positive correlation with the drip loss (p < .01) and a notable negative correlation with the moisture content (p < .01) emphasized the importance of moisture improvement and shear force reduction in affecting tenderness of baked beef meat. The regression equations and R-squared values were revealed the favorable correlation between collagen solubility and WHC (y = 0.1035x-0.8431, R 2 = .98) as well as moisture and WBSF (y = -0.3297x + 102.58, R 2 = .99) in marinated beef meat. Electrophoresis patterns of isolated myofibrillar proteins disclosed remarkable degradation of myosin heavy chain (MHC), desmin, actin, and tropomyosin during the first day of aging. The noticeable ultrastructural destruction and connective tissue solubilization were observed by microscopy images. These outcomes were a good tenderness predictor be utilized in retailing and industrial scale.
RESUMEN
The adverse effects of chemical compounds have limited their usage despite their relative success in improving meat tenderness. Thus, natural tenderizers have attracted attention. The present study aimed to evaluate the tenderization effects of asparagus (Asparagus officinalis L.) juice and balsamic vinegar on beefsteak; marination at 4 °C for 48 h significantly increased the water-holding capacity, total protein solubility, myofibrillar fragmentation index and hydroxyproline content but significantly decreased the pH value, Warner-Bratzler shear force, and energy to the peak rates (P < 0.05). Scanning electron microscopy images and electrophoresis findings revealed extensive degradation of connective tissues and changes in protein band patterns, respectively. The tenderness of the beefsteak samples was optimum by applying 25% asparagus juice, and 25% asparagus juice + 10% balsamic vinegar. Therefore, marinade solutions containing asparagus juice and balsamic vinegar can be considered as natural tenderizing agents in formulation of seasonings and sauces to promote tenderness in tough beefsteak and possibly improve other quality-related properties.
RESUMEN
Since heavy metals have been regarded as ubiquitous environmental pollutants, the exploitation of bacterial biosorption has been suggested as an applicable method for being employed for heavy metal depletion. The present study aimed to characterize the function of Lactobacillus paracasei in the presence of Pb (II) and Cd (II). The simultaneous effect of pH, initial metal concentration, and inoculum size demonstrated the Pb (II) removal of 85.77% at the lowest pH, while the inoculum size was enhanced to 45 CFU/100 ml. The maximum Cd (II) removal was obtained at a high level of pH and inoculum size, while the metal concentration was reduced to 30 ppb. The addition of Cd (II) concentration in access led to the 10% drop in Cd (II) removal efficiency attributed to the metal toxicity and pH. Additionally, the slight variation in the amount of inoculum size caused the decreasing trend in the Cd (II) removal. According to the obtained results, the benefit of L. paracasei in the biosorption of heavy metals was well-recognized, which could be suggested as an alternative candidate. PRACTITIONER POINTS: Strain of Lactobacillus paracasei as potential probiotics was tested for biosorption. A successful response surface method was proposed. L. paracasei showed a good efficiency for the lead and cadmium biosorption. Biosorption process was effective in removing low metal level from drinking water. The maximum biosorption was found to be 85.77% for Pb (II) obtained from the experiment.