Energy and cost analyses of kombucha beverage production

Kombucha is a traditional fermented beverage and it is produced by the fermentation of tea and sugar. Many beneficial effects to the human body can be achieved using substances with antioxidative properties. Substrates for kombucha fermentation contain antioxidants which originated from tea leaves. This study is conducted by kombucha beverage production device that has been invented by authors, located in the Tehran province, Iran. Data is collected from a kombucha beverage production device, performed by 23 replications in capacity of 4.5 L during January-December 2014. Total energy inputs and outputs were calculated as 2.77 MJ L−1 and 8.69 MJ L−1, respectively, therefore the energy productivity and net energy value are estimated as 0.38 kg MJ−1 and 5.92 MJ L−1, respectively. The results show that the highest share of energy is consumed by sugar (40.9%) and kombucha beverage (29%). The ratio of energy outputs to energy inputs is approximately 3.14. The shares of renewable and direct energy were 15.7% and 91.5%, respectively from the total energy input. The net return and productivity from kombucha beverage production were found to be 0.38$ L−1 and 1.03 kg $−1, respectively. The results showed that by increasing volume of kombucha beverage production device, input costs (kombucha fungus, electricity, machinery and rent land expense) will decrease because of proration costs.