Stability Enhancement of Ocimum Sanctum Linn. Essential Oils Using Stearic Acid in Aluminum Carboxymethyl Cellulose Film‐Coated Gelatin Microcapsules

Holy basil essential oils (HBEO) can be used in many food applications due to antioxidant and antimicrobial attributes, but they are susceptible to degradation upon storage. Therefore, a protective system is required to extend their shelf life. HBEO was microencapsulated by coacervation using gelatin and the microcapsules were subsequently coated with stearic acid (1%, 2%, and 3%) in carboxymethyl cellulose emulsions. The results showed that HBEO contents decreased with increasing stearic acid concentrations from 76% to 59%. Fourier transform infrared spectroscopy analysis suggested that HBEO was stable during microencapsulation. After 3‐month storage, changes in appearance were detected in all samples, especially the uncoated and 3% stearic acid‐coated microcapsules. Additionally, the surface HBEO content increased significantly, consistent with a distinct increase in darkness and agglomeration. X‐ray diffraction analysis revealed the physical change of microcapsules, attributed to the renaturation of gelatin and recrystallization of stearic acid. The antioxidant activity of both non‐encapsulated and encapsulated HBEO after storage decreased significantly, except the microcapsule coated with 1% stearic acid (half maximal inhibitory concentration of 0.35 mg/mL), whereas the antimicrobial activity remained constant. The findings suggest that HBEO microcapsules coated with 1% stearic acid could serve as antioxidant and antimicrobial additives in food industries.     

Human visual weighted progressive image transmission

A progressive image transmission scheme which combines transform coding with the human visual system (HVS) model is developed. The adaptive transform coding of W.H. Chen and C.H. Smith (1977) is utilized to classify an image into four equally populated subblocks based on their AC energies. The modulation transfer function (MTF) of the HVS model is obtained experimentally, based on processing a number of test images. A simplified technique for incorporating the MTF into the discrete cosine transform (DCT) domain is utilized. In the hierarchical image buildup, the image is first reconstructed from the DC coefficients of all subblocks. Further transmission hierarchy of transform coefficients and consequent image buildup are dependent on their HVS weighted variances. The HVS weighted reconstructed images are compared to the ones without any weighting at several stages. The HVS weighted progressive image transmission results in perceptually higher quality images compared to the unweighted scheme     

Encapsulation of Holy Basil Essential Oil in Gelatin: Effects of Palmitic Acid in Carboxymethyl Cellulose Emulsion Coating on Antioxidant and Antimicrobial Activities

The challenge of using essential oils possessing antioxidant and antimicrobial properties in food industry is to maintain their chemical stability. This research examined the roles of emulsion coating in preventing the degradation of holy basil essential oils (HBEO) during storage. The uncoated HBEO-loaded gelatin microcapsules and those coated with 1, 2, and 3 % palmitic acid emulsified in carboxymethyl cellulose, denoted as UC, C-1P, C-2P, and C-3P, respectively, had HBEO contents of 76.35, 76.09, 68.96, and 59.39 % with the surface oils of 1.31, 0.65, 0.65, and 0.84 %, respectively. The increase in the palmitic acid concentrations caused a significant increase in the L ^* values (p?<?0.05). After 90 days of storage at 30 °C, the surface oils of UC, C-1P, C-2P, and C-3P significantly increased to 3.65, 2.43, 2.15, and 3.03 %, respectively, coincident with the decrease in the L ^* values. X-ray diffraction studies revealed that the crystalline structures of the microcapsules were influenced by gelatin renaturation and palmitic acid polymorphism. The antioxidant activities, expressed as IC₅₀, of the free and encapsulated HBEO before storage were 0.30 mg/ml. After storage, IC₅₀ of only C-2P remained constant, while those of the rest significantly increased (p?<?0.05). The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of all the samples against pathogenic bacteria did not change over storage. C-3P exhibited the strongest antimicrobial activity of MIC of 0.625 mg/ml and MBC of 1.25 mg/ml. These findings suggest that the emulsion coating enables shelf life extension of HBEO-loaded gelatin microcapsules.