I Kadek Juni Saputra* and Irvan
Mentor: Rike Tri Kumala Dewi
Department of Food Business Technology, School of Applied STEM (Science, Technology, Engineering, andMathematics), Universitas Prasetiya Mulya, BSD City Kavling Edutown I.1, Jl. BSD Raya Utama, BSD City, Kec.Pagedangan, Tangerang, Banten 15339, (021) 30450500 *i.saputra@student.prasetiyamulya.ac.id
Abstract
Pulsed Electric Field (PEF) is a novel tool to increase food shelf life, by running high potential electric pulses to cause irreversible electroporation on microbial cells. This process leads to prolonged product shelf life and much less degradation of vitamins, antioxidants, bio-actives and flavor compounds, leading to health benefits and better quality products when compared to conventional thermal treatment. Heat sensitive products like jamu and juices would highly benefit with this technology. Thus, measures to optimize this process is necessary, specifically for the small-medium food industry. Mixing variable was observed because it is an integral part of thebatch process that is used by the small-medium industry. The aim of this study is to determine the influence of mixing on log reduction in PEF sterilization. This study used ZVS drivers and a flyback-transformer to generate high voltage. Escherichia coli (ATCC 25922) was used as the target organism and total plate count was used to determine log reduction in NaCl 2.5ppm media. PEF sterilization was adjusted on E = 14,4kV/cm, σs = 0,43mS/cm, τ = 20μs, t = 60s and themixing variable was adjusted to five different speeds. Data analysis of mixing speed showed strong negative correlation with log reduction (r = -0.9845), as expressed by the equation y = 4.950 - 0.0269(x) (R2 = 0.9692). The results show that mixing speed is inversely proportional to log reduction, causing the electrical discharge across the media to become slower and weaker, reducing microbial inactivation. Based on this finding, to improve the effectiveness of PEF sterilization and shelf life extension, a design process that minimizes mixing and turbulence is
ideal.
Key words: Batch process, microbial log reduction, mixing, pulsed electric field, sterilization
