TITLE:
Effects of Processing on Antioxidant Capacity and Metabolizing Enzyme Inhibition of Tiger Nut Tubers
AUTHORS:
Shantrell Willis, Cydney Jackson, Martha Verghese
KEYWORDS:
Antioxidant, Tuber, Enzyme
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.10 No.9,
September
27,
2019
ABSTRACT: Tiger
nut (Cyperus esculentus), commonly referred to as chufa, is a “nut-like” tuber, native to
tropical and Mediterranean regions. It is often consumed in the form of a
beverage (horchata de chufa). Health benefits of tiger nut have been attributed
to presence of phytochemicals and their antioxidant potential. Tiger nut is
often processed in order to enhance sensory characteristics. The objective of study was to determine effects of processing on antioxidant
content, potential and inhibition of metabolizing enzyme activities of tiger
nuts. Total phenolic content (TPC), total
flavonoid content (TFC), free radical scavenging activity by
1,1-diphenyl-2-picryhydrazyl (DPPH), trolox equivalent antioxidant capacity
(TEAC), ferric reducing antioxidant power (FRAP) and inhibition of lipase and α-amylase were evaluated in raw tiger
nuts extracted with water (TRWA) and methanol (TRWM) and roasted (110°C – 115°C for 10 mins) tiger nuts extracted
with water (TRA) and methanol (TRM). Highest phenolic content was observed in
TRWA (1186.68 GAE/100g) and TRWM had lowest (43.77 GAE/100g). TRWA also
exhibited highest ferric reducing ability with a FRAP value of 169.83 mm Fe2+/100g).
TRWM had a higher flavonoid content (220.68 CAE/100g) compared to all other
extracts. At a concentration of 0.02 mg/ml,
all extracts reached at least 50% inhibition of DPPH, while highest scavenging
activity was observed in TRM (58%). Highest TEAC was observed in TRM with
55.66% of ABTS radical scavenged. TRA had a significantly higher ability to
inhibit α-amylase and lipase compared to other extracts. Results suggest that
processing had an effect on the antioxidant potential of tiger nut, and this
tuber may benefit consumers by improving their antioxidant status.