Green tea possesses functional properties with attendant health benefits, Nigerian tea leaves has only been commercially processed into black tea. This study therefore evaluated the effect of Steaming Time (ST), Drying Temperature (DT) and Drying time (Dt) on the chemical and sensory properties of Nigerian Green Tea (NGT). Epical bud and two leaves from agronomic proven commercially viable clone were harvested from the Cocoa Research Institute of Nigeria experimental tea plots, Taraba State. Response surface methodology (Central Composite Design) was used to combine the three processing variables: ST (60, 90 and 120 s), DT (60, 65 and 70ºC) and Dt (90, 120 and 150 min). Epigallocatechin gallate (EGCG), Epigallocatechin (EGC), Epicatechin gallate (ECG) and Epicatechin (EC) contents of NGT were determined using High Performance Liquid Chromatography while descriptive sensory evaluation of NGT samples was carried out using semi trained panellist. Data generated were subjected to ANOVA and regression analysis. Results showed that NGT contain EGCG, EGC, EC and ECG contents that ranged from 46.90 to 178, 0.30 to 4.24, 1.03 to 8.83, and 8.05 to 33.96 (mg/g), respectively. Greenness, sweetness, bitterness, and astringency score of NGT extracts were 4.00-6.00, 1.00-2.23, 5.07-7.97 and 1.00-2.23 respectively on a 1-9 intensity scale. This study revealed that acceptable green tea can be obtained from Nigerian tea leaves in terms of chemical constituents, especially for the high EGCG content. The optimum process conditions for NGT were steaming for 60 s and drying at 70ºC for 150 min for high EGCG content and sensory acceptability.
The use of inappropriate temperature-time combinations during roasting of nuts could lead to quality defects, such as burnt taste, dark colour, short shelf-life, rancidity, and poor flavour. The objective of this study was to determine the effect roasting temperature (100-160°C) and time (20-60 min) on colour parameters (L*, a*, and b*-values), Browning Index (BI), Hardness, consumer acceptability and moisture content of both whole cashew-kernel and cashew nut paste using Response Surface Methodology. The experimental runs were established using central composite rotatable design. Second-order polynomial models were developed for predicting the determined product properties. The results showed that CIELAB L*-value of the colour decreased from 54.41 to 41.23 while a*-and b*-values increased from 6.08 to 15.84 and 13.77 to 25.92, respectively, p<0.05 as the temperature and time increased. The moisture content and hardness decreased from 6.35 to 1.02% and 34.24 to 19.94 N, respectively, while BI increased from 47.47 to 97.94 as the temperature and time increased. The results showed that colour parameters (L*, a*, b*-values, BI) of whole cashew-kernel and a*-values of cashew nut paste could be used to monitor the roasting quality of cashew nut. The regression models significantly described the changes in moisture, hardness and colour parameters at p<0.05 (R 2 =0.96). The recommended range of roasting temperature and time of wholekernel for cashew paste was 145°C and 40 min with desirability of 0.85 which is measure of goodness of fit of RSM model. The study showed that the optimized processing conditions produced acceptable cashew kernel and paste of desirable colour and superior flavour quality with short processing time that will enhance direct and commercial utilization.
IntroductionCassava (Manihot esculenta Crantz) is a staple food for over one billion people in the developing world [1]. In Nigeria, it appears to be the major staple food that matches population growth [2,3]. They are highly perishable and cannot be kept after harvest, hence it can either be consumed immediately or processed into various product [2,3]. The main form in which cassava is eaten in West Africa is in a roasted granular form known as gari, a fermented roasted granule prepared from peeled, grated and fermented cassava root through a series of processing steps [3][4][5]. The quality and yield of gari during roasting (garification) is affected by cassava root age and length of cassava mash fermentation. The garification process is an arduous and intricate operation which needs good understanding of the factors that affect the yield and quality of the gari [6]. In recent years, the inability of the process coupled with exposure of the operator to heat and smoke have been the major factors reducing the efficiency of the gari roasting in the traditional methods. The traditional gari processing methods not only gives relatively good quality, but it is highly labour-intensive, unhygienic and productivity is often too low to justify the investment of labour, time consuming and leads itself to health hazard for the operator [7]. Engineering interventions to improve the industrial process is often by way of reducing drudgery and maximizing the yield of gari and improve quality through the mechanization of the unit operations. Considerations for heat and mass transfer are also necessary to improve the working conditions of gari processing for sustainable economic development in Nigeria. The study of [8] has shown that the heat and mass transfer operations play a prominent role during reconstitution of gari into thick paste, and are among the most important physical phenomena occurring during gari processing. As a consequence, several important variables such as temperature and moisture concentration within the structure of food depend on time as well as position inside the food system [9] highlighted that gari yield and quality are highly influenced by cassava variety, maturity age, fermentation and garification temperature, convective heat and mass transfer coefficients. Mathematical modeling and computerbased numerical analyses such as Partial Differential Equation (PDE), Response Surface Methodology (RSM) have been extensively used for time and cost reduction in experimentation, design, optimization and validation of food processing operations [10]. Previous studies of baik [11,12] and Singh and Pandey [13], have shown that ANN model is an advanced modified numerical analysis method, which is capable of learning from examples through iteration and could be useful in predicting simultaneous heat and mass transfer data. ANN model was applied in this study to analyze the garification process to develop an ANN based model of steady state simultaneous heat and mass transfer for the garification process of fermente...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.