Drying guideline to control colour quality of para rubber sheet by computation method

• Published in: Biosystems engineering Vol. 176; pp. 151 - 161
• Main Authors: Junka, Nittaya, Rattanamechaiskul, Chaiwat, Prachayawarakorn, Somkiat, Soponronnarit, Somchart
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2018
• Subjects: Colour kinetics; Drying; Mathematical modelling; Para rubber sheet; Mathematical modelling; Colour kinetics; Para rubber sheet; Drying
• ISSN: 1537-5110; 1537-5129
• DOI: 10.1016/j.biosystemseng.2018.10.009

Colour is one of the most important basic physical characteristics of dried para rubber sheets. This characteristic is used to determine the standards and trading prices. In this research, a mathematical model and a colour change equation were developed for para rubber sheet drying in a hot air oven, with the yellowness index (YI) as an indicator. The results show that the mathematical model provides validation of the moisture change and that the first-order rate reaction equation gives a satisfactory prediction of the colour change. The determination coefficient for every drying condition is between 0.9080–0.9742 and 0.9273–0.9813. Suitable drying conditions were used in the simulation using the model and equation, and the shortest drying time was applied in the study. Moreover, the colour value of the simulated para rubber sheet is not higher than that of the reference Unsmoked Sheet (USS) whose moisture is decreased by sun drying and is still in the best standard range. •Mathematical model was developed to predict the colour of dried para rubber sheets.•The drying temperature and air velocity affected the colour kinetics.•The change in the sheet colour during drying was due to the Maillard reaction.•The proposed first-order equation was suitable to predict the colour kinetics.•The modelling and colour equation suggested appropriate drying conditions.