Shuhada Baharuddin, Nur
(2020)
Lactic Acid Production From Broken Rice
Via Fermentation Process.
Project Report.
Pusat Pengajian Teknologi Industri.
(Submitted)
Abstract
One of the consequences of industrial food production activities is the generation of
high volumes of waste, whose disposal can be problematic, since it occupies large spaces and
when poorly managed can pose environmental and health risks for the population. The rice
industry is an important activity and generates large quantities of waste. The main solid waste
generated in the rice production cycle is broken rice. Broken rice refers to the fragments of rice
grain obtained by milling and separated after the polishing phase. It has the same chemical
composition as white rice and its most important components are carbohydrates. The aim of
this research is to investigate the optimum condition and potential of utilizing fermented broken
rice to the production of lactic acid using different strain of bacteria culture. Different process
parameters such as pH of the medium, temperature, agitation speed and substrate concentration
were used to study the optimum condition. Then, the growth kinetics and modelling of lactic
acid production from broken rice were studied in a batch system. From the screening process,
the highest lactic acid concentration of 5.24 g/L was obtained from Lactobacillus acidophilus
strain at pH 7, Temperature 35ºC, 150 rpm agitation speed and the substrate used was 50 g/L.
Unstructured models were proposed using the logistic equation for growth, the Luedeking-Piret
equation for lactic acid production and modified Leudeking-Piret model for substrate
consumption. The parameters estimation for the experiment data for batch fermentation µmax =
0.2582 h-1, XO = 2.281 g/L, Xm = 8.60 g/L, Yx/s = 0.200 g/g, Yp/s = 0.74 g/g and maintenance
coefficient (ms) = 0.017 g glucose g−1 biomass h−1. From the Leudeking – Piret equations the
α, ß value obtained were 0.179 and 0.014 respectively. Excellent significant R2 values of
0.8452, 0.9245, and 0.9669 were observed for biomass, lactic acid production and substrate
consumption, respectively. The values indicated that the model used was able to interpret the
fermentation kinetic in the batch fermentation. The feasibility study shown broken rice having
high potential to be a new sustainable source for the lactic acid production.
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