The Effect of Vibratory Grinding Time on Moisture Sorption, Particle Size Distribution, and Phenolic Bioaccessibility of Carob Powder.

Carob pod powder, an excellent source of health-promoting substances, has found its use in a wide range of food products. Grinding conditions affect the physical and chemical properties of the powder, but their influence on the bioaccessibility of phenolic compounds in carob pod powder has not yet been determined. The carob pods were ground for 30-180 s in a vibratory grinder. The median values (D50) of particle size decreased after 60 s of grinding (87.9 µm), then increased to 135.1 µm. Lightness showed a negative correlation with D50 and aw, while the values of redness and yellowness decreased with the reduction in particle size and water activity. The smaller the value of D50, the higher the equilibrium moisture content of carob powder. Phenolic acids (vanillic, ferulic, cinnamic) and flavonoids (luteolin, naringenin, apigenin) were found in all samples of carob powder. The grinding time influenced their content in carob powder, with maximum values at 180 s. Similar observations were made when assessing antioxidant capacity. The in vitro digestion process only improved the bioaccessibility of catechin content in all samples. However, the bioaccessibility of the phenolic compounds and the total phenolic and flavonoid contents decreased with the increase in grinding time. Our findings revealed that the grinding of carob pods for 180 s improved the extractability of phenolics; however, their bioaccessibility was reduced. It is sufficient to ground the carob pod for 30 s, ensuring good availability of nutraceuticals and lower energy cost for grinding.

A new voltammetric approach for the determination of ß-carotene in vegetables and pharmaceutical capsules using a gold electrode.

Significant improvements in the voltammetric determination of ß-carotene (BCA) have been achieved, mainly by the replacement of toxic dichloromethane with acetone and using non-mercury electrode. The respective procedure is based on anodic oxidation of BCA at a gold electrode in the disc configuration, when using square-wave voltammetry in pure acetone (99.8%) with 0.1 mol L-1 LiClO4 as the supporting electrolyte. The method comprises extraction of the analyte from the sample with acetone, thus avoiding the usually used highly toxic solvents. Analytically, it can be characterized by a linear range from 6.0 × 10-6 to 5.9 × 10-4 mol L-1 with regression equation Ipa = 0.0184c -0.1631 and correlation coefficient, R2 = 0.9998, limits of detection and quantification LOD = 1.6 × 10-6 mol L-1 and LOQ = 5.4 × 10-6 mol L-1, respectively; both being obtained at a potential step of 5 mV, with the pulse amplitude of 25 mV, and a frequency of 80 Hz. After optimization, the method was evaluated in series of analyses; namely, with two samples of vegetables and two pharmaceutical preparations (capsules), when the results could be compared to those of a reference spectrophotometric method. Due to a simple instrumentation, including sample preparation, the voltammetric method for the determination of BCA can be recommended as a quick screening assay in food and pharmaceutical analysis.