Abstract:
Marula fruit is one of the most underutilized fruits in South Africa, and it has been
reported to contain a high amount of vitamin C which is regarded as the cheapest
antioxidant. The fruit pulp is traditionally extracted and boiled into juice, a process
that adversely affects the vitamin C and bioactive phenolic profile of the resulting
juice. This study evaluated the effects of boiling and steaming on the physicochemical
properties of marula fruit juice. The pH, percentage yield, total titratable acidity (TTA),
total soluble solids (TSS), total phenolic content (TPC), radical scavenging capacity,
and vitamin C content of the fruit juice were examined. The study also investigated
the total carotene, color, and sensory properties of the fruit juice. The results showed
that boiling and steaming significantly decreased the Vit C content of the juice (75.67
and 60.05 mg/100 g) compared to control sample (95.11 mg/100 g). The TPC, radical
scavenging capacity, and total carotene content of the fruit juice increase because the
heating processes softened the matrix of the fruit increasing the extractability of the
phenolics and carotene content of the samples. The color of the marula fruit juice was
increased by both boiling and steaming, while the sensory properties of the marula
fruit juice extracted from steamed marula fruit had the highest scores in all the measured
parameters. Steaming of marula fruit before juice extraction improved the nutritional
composition, antioxidant activities, and sensory properties of marula fruit juice.
