Comparison of Total Soluble Protein Content and SDS-PAGE Pattern Between Four Different Types of Honey

Introduction

Honey is a natural sweetener that is consumed worldwide. Malaysia has various types of honey that are already commercial in the global market. There are two types of honey which blossom honey and honeydew honey. The former is produced from the nectar of flowers, while the latter is produced from secretions of the living parts of plants other than flowers or is a product of bees' excretions (Azevedo et al., 2017). Honeybees (Apini tribe) and stingless bees (Meliponini tribe) are two common main honey producers. Honeybees, also known as Apis mellifera bees, are normally bigger and sting, while stingless bees such as Heterotrigona itama are smaller in size and without a sting. As Naila et al. (2018) mentioned, Apis mellifera bee honey is sweet, while stingless bee honey is a mixture of sweet and sour tastes.

Generally, honey is a viscous solution containing various molecules, including fructose and glucose (80-85%); water (15-17%); ash (0.2%); proteins and amino acids (0.1-0.5%) and trace amounts of enzymes, vitamins, and other substances, such as phenolic compounds (Rao et al., 2016). According to Alimentarius (2001), honey is the natural sweet substance produced by honeybees from the nectar of plants, from secretions of living parts of plants, or from excretions of plant-sucking insects. This official definition is restricted to the honey produced by A. mellifera. It may not apply to stingless bee honey, better known as pot honey, which is very popular for its distinct sweetness mixed with an acidic taste, and fluid texture (Ávila et al., 2019). However, the honey composition varies depending on the plants from which the bee consumes nectar. For this reason, the classification and evaluation of honey have always been a challenge for chemical analysis, especially when honey adulteration is increasing (Ramón-Sierra et al., 2015). Among these two types of bees that produce honey, the demand for stingless bees compared to Apis bees is increasing nowadays because of their medicinal value, which can act as an antimicrobial, anti-cancer, anti-inflammatory and wound healing (Queiroz‐Junior et al., 2015).

Despite the traditional uses of honey as a therapeutic agent, honey has recently been recognized in the development of modern medicine for its valuable nutritional quality (Rao et al., 2016). The common therapeutic properties of most honeys are mostly due to their floral origins. In addition, to its high nutritional value, honey also exhibits significant health benefits such as wound healing, antimicrobial, antioxidant, anti-inflammatory, antidiabetic, and anticancer effects. For example, the benefits of Manuka honey, European bee honey, have been recognized internationally (Zulkhairi Amin et al., 2018). Although there is only a small amount of protein and its byproducts (enzymes, bioactive peptides, and amino acids) available, they are also responsible for the health benefits of honey besides the major components such as flavonoids, phenolic acids, and ascorbic acid.

The use of proteomics approaches is a powerful tool in food science regarding process optimization and monitoring, quality, traceability, safety, and nutritional assessment (Pedreschi et al., 2010). Proteins, together with peptides, are one of the major groups of food components, and they are found in many different organisms of both plant and animal origin. The analysis of the complete proteome of foods can characterize foods with unique quality, food produced by new technologies or food originating from specific geographical areas (authenticity). Proteomics has also been used in market surveillance of genetically modified foods. Another new challenge for proteomics has recently been recognized in studying molecular interactions and differences in food proteomes relevant to nutrition (Corradini et al., 2010). As in the case of food analysis, proteomics techniques present several advantages and can provide useful information to identify proteins in food matrix, to study protein–protein interactions in raw and processed foods, as well as interactions between proteins and other food components, or to identify covalently bound constituents that may be produced during processing (Ibáñez et al., 2012).