Ismail Amin

Proteolytic activity (aspartic endoproteinase and carboxypeptidase) of cocoa bean during fermentation

This study was carried out to examine the changes in cocoa aspartic endoproteinase and carboxypeptidase activities, mass pH and temperature during 144 h (6 days) of fermentation using shallow wooden boxes. The results showed that at 72 h of fermentation, the activity of aspartic endoproteinase was higher than the original value. However, at 96 h the carboxypeptidase activity was higher than its original activity. The study also found a high correlation 0·99 (P<0·05) between the mass temperature with the aspartic endoproteinase at 48 h of fermentation. No correlation was found between the mass pH and temperature with the carboxypeptidase during fermentation. The degradation of vicilin-class globulin was about 88·8% and that of albumin was 47·4% at the end of fermentation.

Authentication of butter from lard adulteration using high-resolution of nuclear magnetic resonance spectroscopy and high-performance liquid chromatography

ABSTRACT Food authentication is an interesting issue for all parties in the food industry, including the fats and oils industry. Some unethical players try to blend high-quality foods, such as butter, with lower ones like lard, therefore, the analytical methods capable of analyzing the adulteration practices must be developed. This study used proton nuclear magnetic resonance spectroscopy in combination with high-performance liquid chromatography for the authentication of butter from lard adulteration. The identification of triacylglycerol composition of lard as a chemical marker for halal authentication is analyzed using high-performance liquid chromatography and high resolution nuclear magnetic resonance spectroscopy. The suitability of proton nuclear magnetic resonance provides a high-performance approach for determination butter adulterated with lard in their entirety of all proton bearing components. Peaks in the region of 2.60–2.84 ppm show special characteristics only present in lard. Only lard has its own unique characteristics which only polyunsaturated fatty acids would give signals 7 at δ 2.63, that corresponded to the chemical shift of the double-allylic methylene protons. In the same way, the intensity of signal at 2.63 ppm, due to methylenic protons in a position α to two double bonds, that is to say, due to the linoleic group. Furthermore, we also correlate some signals between 1H and 13C-NMR spectra for the confirmation of signals.

Estimation of uncertainty from method validation data: Application to a reverse-phase high-performance liquid chromatography method for the determination of amino acids in gelatin using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate reagent

A detailed procedure for estimating uncertainty according to the Laboratory of Government Chemists/Valid Analytical Measurement (LGC/VAM) protocol for determination of 18 amino acids in gelatin is proposed. The expanded uncertainty was estimated using mainly the method validation data (precision and trueness). Other sources of uncertainties were contributed by components in standard preparation measurements. The method scope covered a single matrix (gelatin) under a wide range of analyte concentrations. The uncertainty of method precision, μ(P) was 0.0237-0.1128pmolμl(-1) in which hydroxyproline and histidine represented the lowest and highest values of uncertainties, respectively. Proline and phenylalanine represented the lowest and highest uncertainties value for method recovery, μ(R) that was estimated within 0.0064-0.0995pmolμl(-1). The uncertainties from other sources, μ(Std) were 0.0325, 0.0428 and 0.0413pmolμl(-1) that were contributed by hydroxyproline, other amino acids and cystine, respectively. Hydroxyproline and phenylalanine represented the lowest and highest values of expanded uncertainty, U(y) that were determined at 0.0949 and 0.2473pmolμl(-1), respectively. The data were accurately defined and fulfill the technical requirements of ISO 17025:2005.