Chemico-physical characteristics and quality of locally processed honey in Uganda: implications for local and international honey trade

The government of Uganda has embarked on development and promotion of honey production as a strategy for diversifying exports. Throughout the value chain, maintenance of natural honey quality is essential for ensuring a wholesome product and fetching premium prices from local and export markets. We assessed processed honey samples from supermarkets and an open-stall market in Kampala for gross contamination, moisture content, pH and percentage ash as determinates of quality. Mean pH values ranged between 2.5% and 4.3. All samples had moisture content above 20% while percentage ash content ranged between 0.08% and 1.14%. There were no significant differences (P>0.05) in mean pH (t = 0.09), ash (t = 0.76) and moisture (t = -1.23) content values between honey samples from the supermarkets and those from the open-stall market.

In conclusion, vended honey in open-stall consumer markets in Uganda is of poorer quality and grossly contaminated than those sold in the supermarkets. Furthermore, most honey sold in the supermarkets and open-stall markets have higher moisture and lower pH values than prescribed by both the local (Ugandan) and international regulatory standards. Uganda must enforce quality standards at all levels of honey production, processing and marketing in view of attracting higher premium for honey in both local and international markets.

Introduction

Apiculture today is arguably the fastest growing agricultural sector worldwide (Guoda and Chun 2003). Honey, the major product in the apiculture industry is produced and traded nearly in all countries of the world. Generally, honey from African countries is traded locally. However, low volumes of exports are recorded from a few countries including South Africa, Tanzania and Zambia (Gu et al 2002). In spite of the current low export volumes, the organic honey production systems in most African countries present a huge export opportunity for the continent since there is an almost inelastic demand for quality organic foods in the world markets today (Wilson 2006).

In compliance with the quality requirements for exports, Uganda formulated its National Residue Monitoring Plan (NRMP) in 2004. The plan is aimed at guaranteeing sanitary standards during production, handling and processing of food products to meet quality requirements for the different export markets (UEPB 2005). The country has also recently embarked on development of a honey production and exports strategy. It is on this basis that Uganda has since joined South Africa, Kenya, Tanzania and Zambia on the list of countries that can export honey to the lucrative markets within the European Union. Because of its organoleptic features; typified by a characteristic smoky aroma, Ugandan honey is rated amongst the best in the world (Maku 2004). However, the impact of the NRMP standards on the characteristics and quality of honey processed for the local consumer markets in Uganda has not been assessed. Furthermore, anecdotal evidence and results from earlier studies indicate that poor production, handling and processing practices such as gross contamination, adulteration; boiling and use or reuse of non-food grade containers, especially plastic bags or bottles are still rampant in Uganda (Kugonza and Nabakabya 2008). These compromise quality and may discourage a segment of both local and international consumers who are particular about quality standards.

The current study determined the gross contamination, pH, moisture and ash content values as determinates of quality of processed honey in retail outlets in Kampala as compared to local (UNBS 1993) and the international codex alimentarius (Bogdanov et al 2001) standards.

Materials and methods

Study site

Processed honey was bought from two of the largest supermarkets in the Central Business District (CBD) of Kampala, Uganda (Figure 1). Samples were also bought from Owino, the largest open community market also located in Kampala’s CBD.

Honey sampling

Containers of packed honey were picked from the shelves of the two supermarkets. At least two containers of each brand of packed honey found on the shelves of each of the two supermarkets were picked. For confidentiality, each brand was assigned an alphabetical label ranging from A-H for the eight brands that were encountered. Four samples of non-branded honey were also bought from vendors in Owino community market. Samples were kept at room temperature (25-27°C in Kampala) before analysis. The samples were however, analyzed on the same day of collection.

Analysis of honey characteristics and quality

Each sample was analyzed for type of packaging material, presence of gross contaminants, pH, moisture and ash content as determinants of honey characteristics and quality in accordance with standards of the Association of Official Analytical Chemist (AOAC) operating manual (AOAC 1990).

Assessing gross contamination

Gross contaminants such as dead bees, pollen, grass, soil and other debris were ascertained by careful visual observation.

Determination of moisture and ash content

For determination of moisture content, 10 grams of each honey sample was put in a pre-heated silica crucible. The crucible was then placed in a hot air oven (Memmert 845, Memmert GmbH & Co. KG, Germany) and heated at 105°C for 4 hours. Dry matter content was computed by subtracting the weight of the beaker and its contents after heating from the weight of the beaker and its contents before heating. After determining the moisture content, the sample was further heated in a muffle furnace (Nabertherm, Germany) at 600°C for six hours. The weight in grams of the resultant dry matter was taken as the ash content.

Determination of pH

A bout 10 milliliters of each honey sample was placed in a glass beaker and its pH measured using a pH meter (IQ240, IQ Scientific equipments, China).

Data analysis

Descriptive statistics were generated using the frequency procedures of the statistical programme GENSTAT (GENSTAT®, Version 13). T-tests were used to compare mean values of the different honey quality parameters and p-values less than 0.05 were considered significant.

Results

Honey branding in Uganda

All (100%) honey samples bought from the supermarkets had brand names labeled on the packages. All (100%) of them were local (Ugandan) brand names. All branded honey also had expiry dates inscribed but only one brand (12%) had batch numbers. Samples from venders in the open community market had no brand labels (Table 1).

Table 1: Honey Branding in Uganda
Assigned Brand Label	Brand features
Assigned Brand Label	Brand label present	Brand Registration	Expiry dates on labels	Batch numbers seen on labels	Source of sample
A (n =4)	Yes	Uganda	Yes	No	Supermarket
B(n =4)	Yes	Uganda	Yes	No	Supermarket
C(n =4)	Yes	Uganda	Yes	No	Supermarket
D(n =4)	Yes	Uganda	Yes	No	Supermarket
E(n =4)	Yes	Uganda	Yes	Yes	Supermarket
F(n =4)	Yes	Uganda	Yes	No	Supermarket
G(n =4)	Yes	Uganda	Yes	No	Supermarket
H(n =4)	Yes	Uganda	Yes	No	Supermarket
Not labeled(n =4)	No	Not branded	Not there	No	Venders

Honey contamination

No gross contaminants were seen in branded honey. Contaminants were however, seen in all samples of honey obtained from venders in the open community market (Owino), with pollen (75%) being the most prevalent contaminant (Figure 2).

Honey packaging for consumer markets in Kampala, Uganda

Most (87.5%) branded honey was packaged in airtight plastic containers (Table 2). Only 12.5% of samples with brand names were packaged in airtight food-grade glass containers. All (100%) of the non-branded honey were packaged in reused water or medicine bottles (Photo 1).

Table 2: Honey packaging for consumer markets in Kampala, Uganda
Type of package	Percentage of Honey sampled (%)
Type of package	Branded	Not Branded
Air tight plastic container	87.5%	0%
Air tight glass container	12.5%	0%
Reused plastic water bottle	0%	50%
Reused medicine glass bottle	0%	50%

The pH, Ash and Moisture content of honey samples from consumer markets in Kampala

The values for mean pH, percentage ash and moisture content of the different brands of honey marketed in Kampala are shown in Figure 3. Mean pH values for different honey brands in consumer markets in Kampala ranged from 2.5 (lowest) to 4.3 (highest). Only three (38%) out of the eight brands had mean pH above 3.5. None of the samples had a moisture content below 20%; the mean percentage moisture content of the different brands were in the range of 22.1 (lowest) to 30.7% (highest). Percentage ash content means ranged between 0.08 (least) and 1.14 (highest). As shown in Table 3, there were no significant differences (P>0.05) in mean pH (t = 0.09), percentage ash (t = 0.76) and percentage moisture (t = -1.23) content values between honey from the supermarkets and those from the open community market.

Table 3: Differences in mean pH, Ash and Moisture content of honey samples
Honey property	Source of honey	Mean	t-Statistic	P-Value
pH	Supermarket	3.35
	Open markets	3.30	0.09	0.93
Moisture content	Supermarkets	24.60
	Open markets	26.27	-1.23	0.25
Ash	Supermarkets	0.57
	Open markets	0.72	0.76	0.46

Discussion

All samples from the supermarkets had local brand names. This is a strong indication that most, if not all honey consumed in Uganda today is locally produced and not imported. Although Uganda has traditionally been a net importer of honey, recent official statistics indicate that the trends in import figures have been drastically declining. For instance, Uganda imported 122 tons of honey in 2005 compared to only 54 tons, a year later (in 2006). This further declined to as low as 22 tons in 2007 (UEPB 2009). It is apparent from the present study that Uganda today does not import honey at all. However, since official records indicate that the country actually imports honey, it is likely that most importers are product processors, body care manufacturers and up market hotels but not consumer retail markets.

Samples obtained from open market venders in addition to not being branded (labeled) were also heavily contaminated with pollen, dead bees and soil. This finding strongly supports an earlier observation by Leow (2010), who had this to say about Ugandan honey “Honey producers can target local, regional and global markets. The local market can be sub-divided into two segments. The first such segment is almost purely price-driven. Quality here is not an issue. Honey catering for this market is promoted by street vendors, selling it in all sorts of reused packaging, ranging from soda bottles to used cooking oil containers. Some foreigners or tourists are actually enticed by these vendors in the villages, as they believe honey sold in rural areas is natural and unadulterated. To prove that the honey is pure, the vendors have a practice of dropping a dead bee inside the bottle! The other local segment caters to the retail market such as supermarkets and sundry shops in and around all major districts. In this segment, there is a small group of consumers that go for higher quality honey that has fewer impurities. However, the bigger local demand is still for low priced honey, as most consumers are not particular or have little knowledge about honey standards”.

In this study, only 38% of branded honey and all (100%) non-branded honey sampled from venders in open market stalls, had pH above 3.5. Most of the honey from consumer markets in Uganda therefore do not meet recommended pH values for both local (UNBS 1993) and international standards (FAO 1986; Bogdanov et al 2001). This also agrees with a related study by Kugonza and Nabakabya (2008) who concluded that low pH (high acidity value) could be a significant hindrance to wider acceptance of Ugandan honey. They attributed the low pH of Ugandan honey to heavy yeast contamination due to poor hygiene during handling across the value chain. Yeast contamination leads to increased fermentation with organic acids as major products. Our study however, did not ascertain the fungal load of the samples. It is however worth noting that the PH does not necessarily reflect the acidity values, but rather a buffering action between organic and inorganic acids (Williams et al 2009).

High percentage moisture content (22.1%-30.7%) was observed in all samples of honey. Quality honey will have a moisture content of not more than 18% (Rodruiguez et al 2009). The amount of water contained in honey is critical to its quality and to its stability. Honey with lower moisture levels contains more sugar, and is much less likely to begin fermentation during storage. This is because osmosis draws moisture from any wild yeast cells that may be present and helps to keep the yeast in a dormant state. Conversely, honey with higher moisture levels can become unstable if wild yeasts are present, and spontaneous fermentation will occur, often with a drop in pH (Rodruiguez et al 2009). Honey will also draw moisture from the air, so proper storage should always be an important consideration. We note that, since branded honey were all packed in apparently airtight containers; it is probable that they are often packed with an already high content of moisture. This is what Leow (2010) again had to say in this respect “Packers are normally not beekeepers themselves. Middlemen will travel to villages to buy from various sources and resell at some centralized market in town. Most packers purchase from these middlemen, filter some of the impurities from the honey, pack and label for retail sales. Little or no testing and minimal quality control of the honey is involved. The packers only need to invest in simple filtering equipment, plastic jars and labels”.

Of all honey parameters tested, we observed that, only the ash content (0.01%-1.1%) was comparable to recommended national (UNBS 1993) and international (FAO 1986) values. Only 10% (all from venders in the open stall markets) had ash content exceeding 1.1%. With respect to mineral content, Ugandan honey is hence of high quality albeit quantitatively. The quality of the minerals makes honey valuable for dietetic use. Dark colored honey contains more minerals, mainly iron, copper and manganese which makes it especially fit for medicinal purposes (Gonzalez et al 2000; Buldini et al 2001). Ugandan honey is generally characterized as dark colored, a feature most likely derived from its rich mineral composition (Maku 2004).

We conclude that, honey vended in open-stall consumer markets in Uganda is of poorer quality and grossly contaminated than those sold in the supermarkets. That, except for the ash content, most of the honey sold in the supermarkets and open-stall markets have higher moisture and lower pH values than prescribed by local (Ugandan) and international regulatory standards. Uganda hence, needs to enforce quality standards at all levels of honey production, processing and marketing in view of attracting higher premium for honey in both local and international markets.

Acknowledgments

We are grateful and acknowledge the technical assistance provided by Ms Margaret Nabulime and staff of Nutrition Laboratory, School of Veterinary Medicine, Makerere University, Kampala.

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