Assessment of Quality of Tanzanian Honey based on Physicochemical Properties

Quality of Tanzanian honey based on physicochemical parameters namely water content, sugar content, pH, ash content, hydroxymethyl furfural (HMF) and honey colour was studied using 26 honey samples collected from ten popular honey producing regions. Analyses were carried out in triplicates using standard methods. Data was analysed using averages, correlation and ANOVA tests. Majority of the honeybees’ honey samples were light coloured while all stingless bees honey samples were dark coloured. Dark coloured honeys contained more minerals; mainly iron, copper and manganese which make them especially fit for medicinal purposes. pH values ranged from 2.61±0.12 to 4.37±0.08, stingless bees honey samples were more acidic than honeybees’ honey samples.  Total sugar content values (64.16-84.84 g/100g) were all above the minimum requirement of the national and international standards of not less than 60g/100g. HMF values ranged from 5.0 – 26.4 mg/kg honey, an indication of good quality, being far below the maximum limit allowed by national and international standards of 40mg/kg or 80mg/kg for honeys from the tropics. Of the 26 honey samples studied, all 5 honey samples from stingless bees and 3 from honeybees had moisture content levels above 21%, the maximum limit allowed by national and international standards.. With the exception of two samples from stingless bees, all honeybees honey samples met the minimum requirements of national and international quality standards of maximum allowable ash content of 0.6 %. ANOVA results showed significant differences in the studied physicochemical parameters between groups of honey samples, namely processed honey raw honey and stingless bees’ honey at P<0.05. Pearson correlation analysis showed strong correlation coefficients at P<0.05 between some parameters studied. In conclusion honey colour and moisture content are two important physicochemical parameters that may be used to assess quality of honey. Keywords: Honey quality, Physicochemical parameters, Honey colour, HMF, sugar content, Moisture conten

Evaluation of Antioxidant and Iron Chelating Activities of A Wild Edible Oyster Mushroom Pleurotus Cystidiosus from Tanzania

This study was conducted in order to assess the levels, activities and establish the influence of postharvest storage methods on antioxidants of the giant wild edible mushroom Pleurotus cystidiosus. Standard analytical methods were employed to determine the level and activities of antioxidants. It was followed by comparing the results in order to establish the influence of postharvest storage methods namely heat drying, freezing, sun drying, refrigeration, salt drenching and dehydration using silica gel beads. The mushroom caps and stipes were treated separately. Results showed that irrespective of the preservation method and portion of the mushroom used, P. cystidiosus exhibited very high values of the number of antiradical activity units in 1 mg of extract (EAU515), ranging from EAU515 3.25 to 17.00. The mushroom also portrayed very high 1,1-diphenyl–2picryhydrazyl (DPPH) free radical scavenging ability recorded at very low concentrations of crude extracts (0.0125 to 0.800 mg/ml) and the EC50 values ranging from 0.035 to 0.150 mg/ml. Likewise the highest ferrous iron chelating ability of 98.3% was recorded at a low concentration of 0.80 mg/ml. With respect to the antioxidant activities in relation to the fruiting body portions, there were consistently higher antioxidant levels and antioxidant activities in the cap portion than in the stipe of the mushroom. Preservation method also influenced the antioxidants activities whereby the highest radical scavenging and iron chelating activities were found in the oven dried, silica gel dried and refrigerated mushrooms while, salt drenched mushrooms performed the least. These results suggest that P. cystidiosus contain antioxidant levels and activities which are useful properties for a valuable food source of nutraceutics potential; however, salt drenching method of preservation should be avoided. This giant mushroom is recorded for the first time in the country thus, isolation of its germplasm for spawn production, and subsequent domestication remains to be investigated. Keywords: Antiradical scavenging, iron chelating, antioxidant, wild  Pleurotus cystidiosu

Bioactivity of crude extracts of Ascomycetes isolated from Tanzanian traditionally fermented milk, Mtindi

In an attempt to find potential functional foods in Tanzania, a study was conducted to assess bioactivity of 18 ethyl acetate extracts from nine (9)  Ascomycetes strains. Namely; Candida tropicalis, C. pararugosa, Clavispora lusitaniae, Issatchenkia orientalis, Pichia kudriavzevii, Pichia guilliermondii, Galactomyces geotricum, Debaryomyces hansenii and Yarrowia lipolytica isolated from traditional fermented milk “mtindi”. Lethality test of the extracts was determined using Artemia salina naupalii in a Brine Shrimp Test (BST). The lethal concentration (LC50) obtained ranged from 89.7µg/ml to over 1000 µg/ml.  Bioactivity results showed that, one of the 18 extracts had exhibited a strong antibacterial activity against Staphylococcus aureus, Pseudomonas aureginosa and Vibrio cholera having minimum inhibitory concentration (MIC) values of 0.1653mg/ml on each account. More than 40% of extracts exhibited strong to moderate antifungal activity against Cryptococcus neoformans (MIC 0.16 mg/ml – 1.25 mg/ml). In conclusion, these results suggest that yeasts found in traditional fermented milk have potential biological activity that could be used for treatment of some diarrhoeal and fungal infections and possibly tuberculosis. Key words: Yeasts, Brine Shrimp Test, Antimicrobial Activity, Traditional Fermented mil

Assessment of Antioxidant Properties of Honeys from Tanzania

In this study, levels and properties of antioxidants, antiradical and iron chelating activities of honeybee and stingless bee honeys were determined using standard methods. The relationship between honey colour and the studied antioxidants was also explored. Phenolic content of stingless bees honey samples (mean value 847.6 mgGAE/100g) was significantly higher (P<0.0001) than that of raw (412.6 mgGAE/100g) and processed (218.4 mgGAE/100g) honeybee honey samples, respectively. Mean value of flavonoid content was 84.96 mgRE/100g for stingless bee honeys, 44.82 mgRE/100g for processed honeybee honeys and 41.60 mgRE/100g for raw honeybee honeys. ?-Carotene and lycopene content varied among the three honey categories studied. Honey from stingless bees exhibited higher levels of the two antioxidants than honey bee honeys. Vitamin C content ranged from 20.4 – 66.7 mg/100g in processed honey, 42.5 – 61.6 mg/100g in raw honeybees honey and from 56.2 – 67.6 mg/100g in stingless bee honeys. The number of antiradical activity units in 1 mg of honey (EAU515) varied significantly between the honey categories (P<0.0001). The mean values were 5.21 mg/100g for processed honeybee honeys, 6.8 mg/100g for raw honeybee honeys and 10.6 mg/100g for stingless bee honeys. DPPH radical scavenging and iron chelating activities were highest (lowest EC50) in stingless bee honeys compared to honeybee honeys. EC50 mean value for DPPH was lowest (4.19 mg/ml) in stingless bee honeys, 12.93 mg/ml for raw honeybees honey and 18.03 for processed honeybees’ honey.  Similarly, iron chelating activity was highest in stingless bee honeys (EC50 0.04 mg/ml) followed by raw honeybee honeys (EC50 0.057 mg/ml) and processes honeybee honeys (EC50 0.158). A diversity of honey colours ranging from light coloured to dark honeys was recorded in the samples studied. Majority of honeybee honey colours were described as white and light amber, while all the stingless bee honeys were between light amber and amber colours. There were strong positive correlations among the antioxidants studied (r ? 0.5 at P<0.01). Honey colour intensity was found to correlate positively with all antioxidants studied. Consistently darker honeys were found to contain higher levels of antioxidants than lighter honeys. In overall, Tanzanian honeys studied contains high levels of antioxidants, depicting good quality characteristics for use as food and as medicine. Key words: Antioxidants, DPPH, Antiradical activity, Phenolics, Flavonoid

Program 7 : Educational Material for Reduction of the Effects of Floods and Storm Surges in Coastal Cities: A Case Study of Dar es Salaam City in Tanzania

Appendix 3: Technology-Education Linkage Through Disaster Reduction Hyperbase -Ideas from GCOE-ARS Classroom 2012

Identification of mushroom mycelia using DNA techniques

The suitability of using DNA techniques in the determination of relatedness of mushroom fruiting bodies to isolated mycelia was examined. Nine isolates of edible mushroom mycelia of general Oudemansiella, Coprinus and Pleurotus were identified using fruiting bodies as references. Polymerase Chain Reaction (PCR) in conbination with Restriction Fragment Length Polymorphism (RLFP) analyses were carried out on fruiting bodies and mycelia of the isolates. The internally transcribed spacer region (ITS) and ribosomal RNA gene (rDNA) was amplified using ITS1 and ITS4 primers. The RLFP analysis was carried out on the regions amplified by PCR from fruiting bodies and the mycelia was established by looking at DNA fragment band sizes and patterns. Banding patterns and fragment sizes of DNA obtained from mycelia and their corresponding fruiting bodies were identical and characteristic for the species. Using this technique, it was possible to sort out a case of mistaken identity of Oudemansiella fruiting bodies, which were interchanged with another mushroom specimen during packing. The method is fast, accurate, and could be used for routine screening of edible mushrooms of Tanzania for taxonomical purposes. For the latter purpose, it is required that the RFLP database of taxonomically known species is in place. Tanzanian Journal of Science Vol. 28(1) 2002: 115-12

Discrimination of honeys produced by Tanzanian stingless bees (Hymenoptera, Apidae, Meliponini) based on physicochemical properties and sugar profiles

Honey composition vary according to floral origin and bee species from which it is produced. Understanding the composition of honey is essential for guaranteeing its quality and authenticity, and revealing its potential benefits. Studies on honeys produced by Afrotropical stingless bees are scarce resulting into limited understanding and underutilization. The current study investigated the physicochemical properties and sugar profiles of honeys produced by six stingless bee species (Dactylurina schmidti, Hypotrigona gribodoi, Meliponula beccarii, Meliponula ferruginea, Meliponula togoensis and Plebeina armata) from different vegetation zones of Tanzania. Permutation analysis of variance (PERMANOVA) and Kruskal-Wallis tests were conducted to assess how bee species and vegetation influenced the studied parameters. Furthermore, we employed principal component analysis (PCA) and linear discriminant analysis (LDA) to discriminate honey samples according to bee species and vegetation zones. Our findings show that honey composition was greatly influenced by the identity of bee species which affected 84.6 % of the studied parameters, compared to vegetation zones which affected only 23.1 % of the studied parameters. Stingless bee honey showed significant variation from the international quality standards established for Apis mellifera honey. Also, the levels of free acidity (32.05–99.95 meq/Kg), ash content (0.09–0.81 % w/w) and reducing sugars (43.79–50.82 g/100 g) in some honey samples deviated from the East African Community standards for stingless bee honey. PCA and LDA revealed that the physicochemical properties and sugar profiles can be used to classify stingless bee honeys according to their bee species origin. We recommend further studies to elucidate essential markers that can be used in identifying the entomological source of stingless bee honey

Production of lactic acid from waste sisal stems using a Lactobacillus isolate

No Abstract. Discovery and Innovation Vol. 18(1) 2006: 5-1

The effects of bee species and vegetation on the antioxidant properties of honeys produced by Afrotropical stingless bees (Hymenoptera, Apidae, Meliponini)

Stingless bee honey is widely utilized as a traditional medicine in tropical and subtropical regions. The rich diversity of stingless bees and floral resources in the African tropics presents an opportunity for the production of honeys with diverse therapeutic properties. This study investigated the influence of bee species and vegetation on the antioxidant properties of stingless bee honey. Honey samples were collected from six species of Afrotropical stingless bees in six different vegetation zones of Tanzania, and tested for phytochemical composition and antioxidant activity. Our findings demonstrate that the antioxidant properties of stingless bee honey were influenced by both bee species and vegetation, with the former exhibiting a stronger effect. Honeys produced by different stingless bee species varied significantly in all of the assayed parameters, whereas honey samples from different vegetation zones differed in 80% of the parameters. Further, there was a clear separation of honey samples based on bee species on the non-metric multidimensional scaling (NMDS) and principal component analysis (PCA) plots which suggests that the antioxidant properties can be used as markers for discriminating honeys produced by different bee species. The studied stingless bee species across different vegetation zones produced honeys with remarkable phenolic content (46.80–365.17 mg GAE/100 g), flavonoid content (27.49–210.83 mg QE/100 g), vitamin C (7.42–60.50 mg/100 g), radical scavenging activity (32.75–92.50%) and ferric reducing antioxidant power (68.11–221.23 μmol Fe (II)/100 g). Stingless bee honey presents a promising niche for pharmaceutical research and innovation, particularly for Dactylurina schmidti honey which demonstrated exceptional levels of phytochemicals and antioxidant activity. We encourage future studies to investigate the biologically active components in honeys produced by Afrotropical stingless bees, paving the way for potential applications of stingless bee honey in clinical therapy