Thermal treatment effect on the biochemical composition of honey samples

Abstract

Thermal treatment of honey is commonly carried out to prevent honey from fermentation, crystallization and to facilitate bottling. However, this treatment is known to change the biochemical composition of honey and its quality. In the present study, three honey samples, namely the Tualang, Gelam and Acacia honey were pasteurized at 63 °C for 30 minutes and heat treated at 90 °C for 60 minutes. The study showed that heat treatment at 90 °C up to 30 minutes successfully reduced the moisture content of honey samples to the range of 17.0-19.8 %. The moisture content of less than 20 % is required to reduce the rate of fermentation and crystallization. The biochemical composition of fresh and thermal treated honey samples (90 °C for 30 minutes) such as macro-nutrients (sugars, crude protein, diastase, invertase, glucose oxidase, amino acids and crude fat) and micro-nutrients (minerals and water-soluble vitamins) were analysed and compared statistically. The result of the Principal Component Analysis (PCA) highlighted that diastase, panthotenic acid and crude fat were the most affected parameters after thermal treatment with the first principal component covered for 86.4 % of the total variance. The degradation of diastase and invertase due to the thermal proteolytic digestion contributed to the increment of most amino acids, particularly cystine, histidine, tyrosine and valine. In general, Tualang, Gelam and Acacia honey samples responded differently towards thermal treatment. This was because of the difference in their initial biochemical composition.