Nutritive value of masau (Ziziphus mauritiana) fruits from Zambezi Valley in Zimbabwe.

Ziziphus mauritiana (masau) fruits are consumed by many people in Zimbabwe. The fruits contribute significantly to people's diet when they are in season. The objective of this study was to determine the nutritional content of the fruits and, hence, quantify their contribution to the diet. Samples of masau were collected in two seasons (August 2006 and August 2007). Both macronutrients and micronutrients were determined using standard AOAC methods of analysis. Dry matter content ranged from 21.1±0.2 to 24.1±0.3 g 100 g(-1) of edible portion of the sweet and sour fruits, and 84.8±0.2 to 87.2±0.2 g 100 g(-1) for the dried fruit. Crude protein per 100g edible portion of dry weight ranged between 7.9±0.0 and 8.7±0.0 g, crude fat from 0.8±0.0 to 1.5±0.0 g, crude fibre from 4.9±0.0 to 7.3±0.0 g, ash between 3.0±0.0 and 4.3±0.0 g and carbohydrate between 79.5±0.0 and 83.2±0.0 g. The fruits were rich in vitamin C (15.0±0.0-43.8±0.02 mg 100 g(-1)) and the energy values ranged between 1516.0±1.73 and 1575.0±2.3 kJ 100 g(-1). Furthermore, the fruits contained (mg 100 g(-1) of dry weight) potassium from 1865.0±1.3 to 2441.0±1.1, calcium from 160.0±0.3 to 254.0±0.1, sodium between 185.0±0.1 and 223.0±0.2, magnesium between 83.0±0.0 and 150.0±0.13 and phosphorous from 87.0±0.1 to 148.0±0.5. Manganese and copper contents ranged between 0.7±0.03 and 1.6±0.03, while iron and zinc ranged between 2.1±0.43 and 4.3±0.1, and 0.6±0.0-0.9±0.0 mg 100 g(-1) of dry weight, respectively. The masau fruit is therefore a good potential source of carbohydrates, proteins and micronutrients, such as calcium, potassium, sodium, phosphorous, copper, iron, Vitamin C and zinc.

Yellow maize with high ß-carotene is an effective source of vitamin A in healthy Zimbabwean men.

BACKGROUND: The bioconversion efficiency of yellow maize ß-carotene to retinol in humans is unknown. OBJECTIVE: The objective of this study was to determine the vitamin A value of yellow maize ß-carotene in humans. DESIGN: High ß-carotene-containing yellow maize was grown in a hydroponic medium with 23 atom% (2)H(2)O during grain development. Yellow maize ß-carotene showed the highest abundance of enrichment as [(2)H(9)]ß-carotene. Eight healthy Zimbabwean men volunteered for the study. On day 1 after a fasting blood draw, subjects consumed 300 g yellow maize porridge containing 1.2 mg ß-carotene, 20 g butter, and a 0.5-g corn oil capsule. On day 8, fasting blood was drawn, and subjects consumed 1 mg [(13)C(10)]retinyl acetate in a 0.5-g corn oil capsule and 300 g white maize porridge with 20 g butter. Thirty-six blood samples were collected from each subject over 36 d. Concentrations and enrichments of retinol and ß-carotene in labeled doses and serum were determined with the use of HPLC, gas chromatography-mass spectrometry, and liquid chromatography-mass spectrometry. RESULTS: The area under the curve (AUC) of retinol from 1.2 mg yellow maize ß-carotene was 72.9 nmol · d, and the AUC of retinol from 1 mg retinyl acetate (13)C(10) was 161.1 nmol · d. The conversion factor of yellow maize ß-carotene to retinol by weight was 3.2 ± 1.5 to 1. CONCLUSION: In 8 healthy Zimbabwean men, 300 g cooked yellow maize containing 1.2 mg ß-carotene that was consumed with 20.5 g fat showed the same vitamin A activity as 0.38 mg retinol and provided 40-50% of the adult vitamin A Recommended Dietary Allowance. This trial was registered at clinicaltrials.gov as NCT00636038.

Yeasts and lactic acid bacteria microbiota from masau (Ziziphus mauritiana) fruits and their fermented fruit pulp in Zimbabwe.

Masau are Zimbabwean wild fruits, which are usually eaten raw and/ or processed into products such as porridge, traditional cakes, mahewu and jam. Yeasts, yeast-like fungi, and lactic acid bacteria present on the unripe, ripe and dried fruits, and in the fermented masau fruits collected from Muzarabani district in Zimbabwe were isolated and identified using physiological and molecular methods. The predominant species were identified as Saccharomyces cerevisiae, Issatchenkia orientalis, Pichia fabianii and Aureobasidium pullulans. A. pullulans was the dominant species on the unripe fruits but was not isolated from the fermented fruit pulp. S. cerevisiae and I. orientalis were predominant in the fermented fruit pulp but were not detected in the unripe fruits. S. cerevisiae, I. orientalis, P. fabianii and S. fibuligera are fermentative yeasts and these might be used in the future development of starter cultures to produce better quality fermented products from masau fruit. Lactic acid bacteria were preliminary identified and the predominant strains found were Lactobacillus agilis and L. plantarum. Other species identified included L. bifermentans, L. minor, L. divergens, L. confusus, L. hilgardii, L. fructosus, L. fermentum and Streptococcus spp. Some of the strains of LAB could also potentially be used in a mixed-starter culture with yeasts and might contribute positively in the production of fermented masau fruit products.