Journal homepage: www.fia.usv.ro/fiajournal Journal of Faculty of Food Engineering, Ştefan cel Mare University of Suceava, Romania Volume XIX, Issue 1 - 2020, pag. 14 - 24 EFFECT OF SEASON ON THE MAJOR PHYSICO-CHEMICAL PARAMETERS OF HONEY PRODUCT *Destaw ENGIDAW1, Ketema ALEMAYEHU2, Seid MUSTOFA2, Alebachew TILAHUN3 1Department of Chemistry, College of Natural and Computational Science, Debre Markos University, Debre Markos, Ethiopia, P. O. Box 269, [email protected] 2Department of Chemistry, College of Natural and Computational Science, WolaitaSodo University, WolaitaSodo, Ethiopia, P. O. Box 138. 3School of Veterinary Medicine, WolaitaSodo University, WolaitaSodo, Ethiopia, P. O. Box 138. *Corresponding author Received 19th November 2019, accepted 30th March 2020 Abstract The study was conducted to determine the major physic-chemical parameters and to investigate the effects of season on the quality of honey product collected from Dawuro zone, Southern nationalities of people region of Ethiopia. The contents of physic-chemical parameters within the three honey production seasons ranged as: moisture content, 15-18%; electrical conductivity, 0.27-0.31mS/cm; pH, 4.0 - 4.5; free acidity, 18.7 - 24.7meq/kg; lactone acidity, 5.7 - 8.0meq/kg; HMF content, 16.1- 20.3mg/kg; reducing sugars, 70 - 72g/100g and sucrose content from 2.4 - 2.8g/100g. This study showed that there were some significant variations for the contents of the different physicochemical parameters between the different honey production districts and seasons. It was confirmed that the results were below the maximum permissible limit to conform to international standards concerning the good quality of honey. Although, the honey collected in this area should be consumed as fresh to avoid further contamination. Moreover, further studies of other quality parameters of honey are needed. Keywords: Acidity, Dawuro, electrical conductivity, hydroxymethylfural, moisture, sugars and quality 1. Introduction the honeycomb and use for different usages without further purification and the Honey is a thick, golden liquid produced quality of honey is unknown. Different by industrious bees and saved inside the factors such as nectar source of the plant, beehive for eating during times of the variety of bee, seasonal variation and scarcity[1, 2].It is an ingredient of several improper handling and harvesting may industrial products and has been used for a contaminate and reduce honey quality[8- long time because of its antioxidant and 11]. There are different types of honey antibacterial properties[3-5]. quality parameters, but in this study The major ingredients of honey include a moisture content, electrical conductivity, mixture of carbohydrates, organic acids, pH and acidity, the content of 5- amino acids, proteins, minerals, vitamins hydroxymethyl-2-furaldehyde (HMF), and and lipids [1, 6,7]. The presence of these reducing sugars and sucrose contents were major food ingredients in honey made considered. human beings to use it as food sweetening Carbohydrates are the primary components and other human health care. As a result, of honey especially for blossom honey human beings remove and collect it from glucose and fructose concentrations must 14 Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefancel Mare University - Suceava Volume XIX, Issue 1 – 2020 be ≥ 60g/100g and sucrose concentration Nation Nationalities and People Region; ≤5g/100g[2, 6, 12, 13]. Water is the SD: standard deviation; SPSS: Statistical second-highest component of honey and package for the social sciences low water content is desirable because honey may begin to ferment and lose its fresh quality if it is above 20% [2, 14]. 2. Materials and methods Electrical conductivity is an important 2.1. Description of the study area criterion to determine the botanical origin The study was conducted in Dawuro zone, of honey and depends on the mineral SNNPR, Ethiopia with four woredas content, organic acids and proteins of (districts) namely Loma, Mareka, Tocha honey [15-17]. Naturally, all kinds of and Isara that were selected purposefully honey are acidic generally with the pH depending on the areas where the high values between 3.4 and 6.1[1, 18]. The honey product is available. Dawuro zone free acidity of honey was also mostly due is located in southern nation nationalities to the presence of mineral and organic and people regional (SNNPR) state of acids [19, 20]. Ethiopia with an approximately 500km Honey might also contain 5- from Addis Ababa the capital city of hydroxymethyl-2-furaldehyde (HMF) Ethiopia and it is found between 6o36' to which is a water-soluble heterocyclic 7o21' north latitudes and 36o68' to organic compound derived from the acid- 37o52'east longitudes with an altitude of catalyzed dehydration of hexose sugars 500 to 3000meters above sea level. [21-23]. HMF is only present in trace amount in fresh honey and its 2.2. Sample Collection concentration has been reported to increase The honey samples were collected in the with storage and the prolonged heating of three different honey production seasons in the honey [10, 11, 24,25]. The amount of a year; December (2015), June and HMF present in honey is the reference October (2016) for each woreda. The used as a guide; the higher the HMF value, collected honey samples were labeled and the lower the quality of the honey is transported to WolaitaSodo University and considered. stored at room temperature for 5 - 6 In Dawuro zone there are different months until sampling preparation and apiculture areas with high potential of analysis. honey production in the different season especially during October, December and 2.3. Preparation and analysis of the around June but there was no documented honey sample data concerning the quality of honey which Unwanted materials such as wax, sticks, makes this zone impossible to be dead bees and particles of combs were competent in the honey commercial removed by straining the samples by clean market. Therefore, the main purposes of cloth before analysis. All measurements this study were determining the quality of during each season were carried out in honey and to generate quality information triplicate to determine the physicochemical that can be used as baseline data to create properties of honey. international market linkage. The moisture content of each honey Abbreviations: sample was determined by weighing 5g of EC: electrical conductivity; FA: free acid; the sample on a pre-weighed drying dish HMF: 5-hydroxymethyl-2-furaldehyde; and the samples were dried at 105oC to LA: lactone acidity; SNNPR: Southern Destaw ENGIDAW, Ketema ALEMAYEHU, Seid MUSTOFA, Alebachew TILAHUN, Effect of season on the majorphysicochemicalparameters of honeyproduct, Food and Environment Safety, Volume XIX, Issue 1 – 2020, pag. 14– 24 15 Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefancel Mare University - Suceava Volume XIX, Issue 1 – 2020 constant weight in an oven (DHG-9055A, solution and the same solution after the Yunboshi, Jiangsu, China)[26]. addition of bisulfate was determined. Moisture (%) = 푊1−푊0 푥100 The HMF content was calculated after the 푚 subtraction of the background absorbance where W is the weight of the empty dish, o at 336nm [14]. The HMF content of the W is the weight of dried sample + dish 1 samples was calculated by the following and m mass of sample taken formula: The electrical conductivity of each sample HMF (mg/kg) = (A -A ) x149.7x5xD/w was measured on a solution of 20% honey 284 336 where A = absorbance at 284nm, A dray matter at 20 0C with a previously 284 336 = absorbance at 336nm, 149.7 = factor calibrated conductivity meter (HQ40D, W = weight of sample taken and D= Hach Company, Colorado USA). dilution factor, if dilution is necessary Free acid, lactones, and pH were The apparent reducing sugars and content determined by equivalence point of sucrose were determined by the titration[14, 27]. Five grams of honey [M] modification of Lane-Eynonprocedure were dissolved in a few milliliters of water. involving the reduction of Soxhlet’s The solution was transferred quantitatively modification of Fehling's solution by to a 50 ml volumetric flask and filled to the titration at the boiling point against a mark with water. Twenty-five mL of solution of reducing sugars in a honey solution was dropped into a 250 ml beaker solution using methylene blue as an in the presence of a bar magnet. The initial internal indicator[14, 28]. pH (pHi) was recorded and titrated first Two grams and six decigrams of honey with the sodium hydroxide solution (up to were weighed and transferred to 500mL 10 ml), (free acid determination) then (into volumetric flask. Five milliliters of the same beaker) with the sulphuric acid standardized Fehling A and B solutions solution (up to the second equivalence were transferred to a 250mL Erlenmeyer, point) for lactone determination. The free with 7mL of water and 15mL of honey acidity (FA) is expressed in solution. The Erlenmeyer was heated and milliequivalents of sodium hydroxide 1mL methylene blue (0.2 %) was added. required to neutralize 1 kg of honey. Titration was conducted by adding the F.A. = V x T x (50/25) x (1000/M) diluted honey solution until the indicator The lactone acidity (LA) is expressed in was decolorized. Determination of sucrose the same units: content was carried out by inversion, L.A. = [(10-V) x T - 0.05 x V´] x adding 10mL of diluted HCl, 50mL diluted (50/25) x (1000/M) honey solution and water to a 100mL Note from the curve the free acidity volumetric flask, heating in a water bath, neutralization volume in ml [V] and the then cooling and diluting to mark. Finally, sodium hydroxide excess neutralization the Lane-Enyon method was applied and volume (corresponding to pH 7) in ml sucrose content was obtained by [V´]. difference. The amount of HMF was determined by The percentage of reducing sugar before measuring the UV absorbance of HMF at and after inversion was calculated as 284nm by using UV-visible digital follows; spectrophotometer (Model 371, Electronics 퐶 = 2 푥 1000, India, and New Delhi India).