A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of
Doctor of Philosophy in Life Sciences of the Nelson Mandela African Institution of Science
and Technology
Avocado and mango seed kernels are considered as wastes although they are rich in essential
nutrients and bioactive compounds for human health. Lack of commercial application, presence
of anti-nutrients, difficulty in processing and little information on nutritional and functional
values contribute significantly to their underutilization. These factors underscore the need for
processing these seeds into consumable products to utilize them as functional foods. The aim of
this study was to optimize a processing technique capable of reducing antinutrients to acceptable
levels (above 50%), retain nutrients and functional values, and improve sensory qualities of
avocado and mango seeds-based composite flour for functional foods. Different processing
conditions for probiotic fermentation, boiling and soaking techniques were studied to optimize
processing conditions for the seeds. The antinutrients, antioxidant activity, total phenolics and
selected nutrients of the seeds were analyzed using standard analytical methods. Furthermore,
avocado and mango seeds-based composite flour was formulated using Nutrasheets integrated
with the USDA National Nutrient Database for Standard Reference. The formulated composite
flour was assessed for safety and quality parameters for a period of 84 days under different
storage temperatures. The results showed that all processing techniques significantly (p < 0.05)
reduced the antinutrients by over 50% for processed avocado and mango seed kernels. The
highest total phenolics and antioxidant activity (IC50) for both seeds were observed at a
fermentation temperature of 37oC with Lactobacillus plantarum. Soaking and boiling reduced
the analyzed minerals in both avocado and mango seed kernel except for potassium and zinc on
soaked mango seeds, whereas probiotic fermentation retained 100 % or increased the
concentration of the analyzed minerals, ascorbic acid and α-tocopherol. In contrast, boiling and
soaking reduced the contents of ascorbic acid and antioxidant activity of the analyzed samples.
The Nutrasheets analysis showed that the formulated composite flour can achieve the nutritional
and functional values for the functional foods. The shelf life analysis showed that 115 days (4
months) is the maximum shelf life for the flour where all the assessed safety and quality
parameters can still be within the maximum recommended tolerable limits for human
consumption. Therefore, the results of this study indicate that unlike boiling and soaking
methods, the probiotic fermentation is an optimized processing method which can significantly
reduce the antinutrients to acceptable levels, retain nutrients and bioactive compounds, and
improved sensory attributes of avocado and mango seeds-based composite flour for functional
foods.