This study investigated the effect of fermentation conditions (time and temperature) of sorghum on the composition of ting, using the Doehlert design of response surface methodology (RSM). Practical applicationsResponse surface methodology was used to study the influence of fermentation conditions on the quality of ting and optimal fermentation conditions were obtained at 34 8C for 24 hr. The findings in this study will be useful for ting processors to obtain a product with maximal beneficial composition and traits.

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The objective of this research is to assess the effect of enzymatic treatment of guava puree on the physicochemical parameters of the juice. Pectinases from Aspergillus niger were applied to the puree at 43 AE 3 C under constant stirring. Enzyme concentrations used were: 0.033 % (w/w), 0.055% (w/w), 0.078 % (w/w) and 0.1 % (w/w). For each enzyme concentration, the treatment times were varied from 3 -90 min. Physicochemical parameters of raw puree and enzymatically treated juice were determined. These were: viscosity, pH, electric conductivity, protein and polyphenol content, galacturonic acid content, color, TSS, and antioxidant capacity. Particle distribution, homogeneity of raw puree and juice samples dried extracts were assessed using a Field Emission Scanning Electron Microscopy (FESEM). A 91% viscosity decrease was recorded for each enzyme concentration after 3 min of enzyme reaction. That drecrase was accompanied by an increase in galacturonic acid content with increasing depectinization factors. Enzyme treatment of guava puree led to a decrease in pH, protein and polyphenol contents and an increase in conductivity and color. Analysis of FESEM images of guava samples bestowed a decrease in particle size, a scattering of particles in the medium, an increase in continuous phase proportion and an improvement of sample homogeneity with increasing values of processing parameters, due to the breaking-down of bigger particles and the solubilization during depectinization.

J. Inst. Brew. 116(1), 62-69, 2010The effect of commercial enzymes on liquefaction of starch from unmalted sorghum was studied. The effects which these enzymes had on rates of filtration were evaluated. Models were developed, validated and optimized to establish the actions of enzymes, either alone or in combination. Preliminary studies on the sorghum cultivars Safrari, Madjeru and S.35 showed that α-amylase was the backbone enzyme for starch liquefaction among the enzymes used (α-amylase, Filtrase, protease and β-amylase). Models confirmed this observation as α-amylase individually in its first order (X 1 ) contributed 25, 11 and 17%, and in its sum of first and second orders (X 1 +X 1 2 ) contributed a 29, 31 and 36% yield of filtrate for Safrari, Madjeru and S.35 respectively. The ease of starch liquefaction, assessed by summing the first and second orders of individual intervention of all enzymes, was found to be in the order of Madjeru, S.35 and Safrari (79, 70 and 56% of yield of filtrate respectively). The importance of the enzyme combination in starch liquefaction in Safrari, S.35 and Madjeru was shown to be 44, 30 and 21% respectively. Enzyme combinations giving maximal starch liquefaction, as identified from a Doehlert experimental matrix, displayed a similar yield of filtrate (Safrari: 85 mL, Madjeru: 84 mL and S.35: 81 mL) after filtration of a 130 mL mash during 1 h. Validation of t he models revealed the model developed for Madjeru was the most reliable (R 2 = 0.994), while those developed for Safrari (R 2 = 0.987) and S.35 (R 2 = 0.976) were slightly less reliable. Model optimization gave theoretical enzyme (Brewers Amyliq TS, Filtrase NLC, Brewers Protease and β-amylase) combinations of 25 mg, 5.68 mg, 100 mg and 67.

Decoction extraction procedure was implemented to regain phenolic compounds from C. citratus leaves. The extraction variables, solid/liquid ratio (2-5 g/100 mL), temperature (85-95 C), and time (5-10 min) were assessed by central composite design for process optimization. Antioxidant activity (DPPH) and total polyphenol content (TPC) were monitored as responses. The TPC and DPPH were 71.98 AE 0.33 mg GAE/100 mL extract and 80.63 AE 0.49 mg TE/100mL extract respectively under optimal conditions (solid/liquid ratio ¼ 5, temperature ¼ 93.8 C and time 11.3 min). The evaluation of phenolic compounds and volatile compounds of C. citratus extract at conditions for optimum extraction revealed that caffeic (20.81 AE 0.003 mg/100mL) and syringic acids (18.63 AE 7.390 mg/100mL) were the main phenolic compounds while citral and geraniol were the primary volatile compounds. The results achieved herein suits the potential use of C. citratus extract as natural source of antioxidant and aroma compounds that can be employed in different industrial sectors. Practical application: Lemongrass obtained at the optimal extraction conditions is a good source of antioxidants and the extract has organic acids and a lemon scent due to the presence of citral. This extract can thereby be incorporated in the production of beverages which can help aromatize the beverage and also contribute in the addition of the antioxidant property of the beverage. It is also rich in organic acids, the main being propionic acid, which is known to have antimicrobial activity primarily against bacteria and mold. The lemongrass extract can therefore, extend the shelf life of the beverage they are incorporated in and also the citral present in lemongrass has antimicrobial properties.