The aim of the present study was to investigate the effect of withering timings (i.e. 0, 21, 22, 23 and 24h) on the moisture, total free amino acids, ash, essential and toxic mineral element contents of tea (Camellia sinensis L.) leaves during black tea manufacturing. Moisture, ash, Na, P, Mg, Cu, Zn, Mn, Al, Ni and Pb contents were significantly (P0.05) results were noted for total free amino acids, K, Fe and Cd contents. The highest moisture content (76.4%) was examined in fresh leaves that progressively decreased to 63.8% in 24h withering. Total free amino acid contents gradually increased up to 23h and then decreased. Ash, P, Cu, Zn and Mn contents showed an increasing trend with withering time. Conversely, significantly lowered amounts of Na (162.5mg/kg) and Mg (803mg/kg) were recorded in tea leaves after 24h withering. Among the toxic elements, Al, Ni and Pb contents were progressively increased over withering time. It was concluded that tea is a potential source of essential chemical constituents and during processing proper care should be taken to produce high quality black tea

Whole wheat flour was fortified with premix containing ferrous sulfate, ethylenediamine tetraacetic acid and folic acid (20.0:20.0:1.5 ppm) and was stored at ambient temperature for 60 days. Naans (flat bread) were prepared from 0 ppm, 25 ppm, 50 ppm and 75 ppm ferrous iron-fortified flour samples at 10-day intervals and were analyzed for physicochemical constants and sensory evaluation. It was observed that flour containing 75 ppm ferrous sulfate contained the highest iron residues. The total iron in flour samples showed no significant difference, while ferrous iron significantly decreased in fortified flour (0.53–3.08%) and in the naans (0.42–3.48%) because of its oxidation to ferric iron during storage. The phytic acid content decreased (0.886–0.810%) significantly during the same storage period. Iron levels affected some sensory characteristics significantly (P≤0.05), including color, texture, flexibility, chewability and overall acceptability of the naans, but not taste and flavor. The sensory attributes of naans illustrated that naans containing 50 ppm ferrous iron are more acceptable than those prepared with 75 ppm ferrous iron.

The objectives of this study were to examine the effect of different water activities (a_w; 0.99, 0.96 and 0.94) and time (up to 120 h) on quantitative and specific enzyme production during germination and initial growth of Aspergillus flavus and A. parasiticus strains at 25 °C. This is an important early indicator of potential for aflatoxin production under conducive conditions. Qualitative API ZYM generic enzyme strips were used to identify key hydrolytic enzymes produced. Subsequently, the temporal effects of a_w on the total/specific activity of the key 4-5 hydrolytic enzymes were determined using 4-nitrophenyl substrates in a 96-well microtitre plate assay. The main enzymes produced by germinating conidia of A. flavus were esterase, lipase, acid phosphatase, β-glucosidase and N-acetyl-β-D-glucosaminidase, while for A. parasiticus these were alkaline phosphatase, lipase, acid phosphatase and β-fucosidase for both total (µmol 4-nitrophenol/min/g) and specific activity (nmol 4-nitrophenol/min/µg protein). There were significant increases in the specific activity of all these enzymes of germinating spores of A. flavus (0-120 h) except for β-glucosidase which was maximum at 72 h. The total/specific activities of the enzymes produced by A. flavus were maximum at 0.99 a_w, with the exception of acid phosphatase and N-acetyl-β-D-glucosaminidase at 0.94 a_w. For A. parasiticus, maximum total activity occurred at 0.99 a_w for fucosidase activity, while specific activity was found to be higher at lower a_w levels. These enzymes are important in early colonisation of food matrices by these species and single factors (a_w, time) and two-way interactions were all statistically significant for the enzymes assayed for both species. These enzymes could be used as an early and rapid indicator of the activity of Aspergillus section flavi species and suggests that rapid infection may occur over a wide range of a_w conditions.