CHAPTER 6 SUMMARY, CONCLUSION, RECOMMENDATIONS AND
temperatures of (90, 120, 150 ) to obtain a dry and light-brown coloured BSG extract powder.
Despite the development that has been made in the research of the BSG extracts. The economic feasibility of the extraction of polyphenols from the beer production waste has not been explored. The current research work presented in this thesis covered the modelling and simulation as well as the economic evaluation for the process of extracting BSG extracts using SuperPro Designer® Software.
The batch process was selected as the mode of operation for the modelling and simulation of the process. The base case simulation was constructed from the experiments that had been done in the laboratory previously. The information used for unit procedures and equipment was mainly derived from Couper, (2005). Assumptions such as Set up time (SUT) of 5 min and Start time (ST) of 5 min were considered for all unit operations in this work. The process was simulated to obtain the material balances that could be generated by the software. The prices of BSG was adopted from Fernandez-Pérez et al., (2008) and the price of BSG extract powder was taken as 1% of p-coumaric acid price found on the world market (Alibaba, 2017).
6.2 CONCLUSIONS
The main outcome of this work was the development of commercial process for the extraction of polyphenols from BSG. The development of the process included the conceptual stage where experiments were done in the lab and the modelling and simulation done using the SuperPro Designer® Software.
In the conceptual stage, maceration extraction method was used to recover the BSG extracts. Based on the experiments done, water was found to be the suitable solvent for extraction. These results were however not in agreement with those of Meneses et al., (2013b) and Moreira, (2012) who reported acetone 70% v/v as the solvent that gave the best extracts. All the solvents used in this work showed antioxidant activity with extracts obtained using water giving the highest.
In selecting other factors response surface method was used to optimize the process.
Temperature, solvent to fluid ratio and shaking speed were taken from literature data as independent variables. Central composite design was used with the 2FI model to investigate the impact of the variables on the responses. The model was found to be significant for all responses. However, the lack of fit was insignificant which might have implied that the independent variables have no impact on the responses. In order to investigate the time
required for maceration and the speed at which extraction occurs, a kinetic study was done.
The samples were being withdrawn at an interval of 10 min. The study showed that the 15 mins is enough to extract most of the polyphenols. Temperature showed to have insignificant impact on the rate of extraction in this work. The data obtained from conceptual stage was used for the modelling and simulation using SuperPro Designer® software to evaluate the economic feasibility of this process
Three profitability indicators were used in this work namely Return on Investment (ROI), payback period and Net present value. The ROI of the base case simulation was found to be -51.90 %. This made the process to be economically unattractive having a ROI less than 30
%. This led to the development of alternative schemes with debottlenecking strategies to eliminate major limitations. The tray dryer and evaporator were the scheduling bottlenecks and eliminating these would increase the number of batches and consequently the ROI.
However, scheme 1 to scheme 3, were not good enough to make the process economic feasible. Therefore, a value addition on the end product was introduced by adding a packaging line. The packaging line would produce encapsulated 500mg bottles of BSG extract instead of the bulk powder. This value addition made the process to be economically attractive with a ROI of 48.45 % and a payback period of 2.06 %.
6.3 RECOMMENDATIONS FOR FUTURE RESEARCH
Several technical difficulties were noted during the course of the experiments. These are described below for each of the test conducted.
Exogenous factors
Although the BSG was obtained from the same brewing recipe throughout, there may have been factors outside of the control of this project that may have affected either the extraction or the model produced therefrom. Such factors could have been the natural variation in the particular batches of brew or their feed material, detail of which the researcher had no access to. However, these variations can be assumed to be limited, and of such a nature as to be expected in a commercial scale process, and therefore are deemed to be incorporated within the process model proposed.
shaking of samples during experiments
The method of shaking, using a bench-top shaker, is one that is not commonly used in industry and may therefore be difficult to reproduce at commercial level. It is therefore recommended that the experiments be carried out at pilot scale in order to select the equivalent mixing regime using a different method of agitation, such as with a mixing paddle.
Filtering of sample when using water as a solvent
The filtering of fine BSG extraction mixtures was difficult using a filter paper because of the thick mixture that would have been formed. An investigation of the use of centrifuge at commercial scale could be considered.
6.4 CONTRIBUTIONS
By completing this research work, the contributions made are as follows:
Additional data has been generated regarding the extraction of bioactive compounds from BSG, including the kinetics of extraction.
Additional data has also been generated regarding the antioxidant activity of the extracts from BSG.
The developed process will assist in commercialising the extraction of BSG extracts with an attractive margin. Results showed that giving a good packaging to the products can add value to the process.