Functional Components in Peanuts

Abstract

Peanut is one of the most widely used legumes due to its nutrition and taste. The fact that is has been recognized recently as a functional food, its evaluation for its role in a heart-healthy diet has received tremendous attention. Functional compounds have been isolated, identified, quantified, and even enhanced to maximize the amount for adequate health benefits. The peanut industry's byproducts such as peanut hulls and shells, skins, and even leaves and roots have also been identified as possible sources of bioactive compounds. New uses for these underutilized renewable sources can create new market opportunities and increase the value of agricultural residues.

Keywords:

• peanuts
• Arachis hypogaea
• functional foods
• flavonoids
• phenolic acids
• plant sterols
• stilbenes
• antioxidants

Notes

^a A denotes A-type linkage between polymers; B denotes B-type linkage between polymers.

^b Af, C and GC represent constituent units (epi)afzelechin, (epi)catechin, and (epi)gallocatechin.

* Denotes the presence of 3-O-gallate.

^c The “1-5” or “1-P” in column “DP values” indicated that monomers through pentamers or polymers were detected. The average DP determined by thiolysis for selected foods is presented in parentheses.

^d Expressed as mg/100 g on the basis of wet weight.

^e Proportion of the polymers calculated based upon weight.

^a tr – present in trace amounts

^b nd – not detected

¹Compounds highlighted are present in peanuts.

²Measured as the TEAC (Trolox equivalent antioxidant activity) – the concentration of Trolox with the equivalent antioxidant activity of a 1 mM concentration of the experimental substance.

³Antioxidant activity expressed as VCEAC (Vitamin C equivalent antioxidant capacity) – the ABTS radical scavenging activity expressed as mg/L vitamin C equivalents at 10 min; nd - no data.

¹ Compounds highlighted are present in peanuts.

² Measured as the TEAC (Trolox equivalent antioxidant activity) – the concentration of Trolox with the equivalent antioxidant activity of a 1 mM concentration of the experimental substance.

³Designated Ep/2. An Ep/2 of < 0.2 indicates a chemical that is readily oxidized and therefore an efficient free radical scavenger.

¹Raw peanuts were sliced to 2 mm, exposed to ultrasound for 4 min at 25°C, and incubated for 36 h at 25°C.

²Raw peanuts were stressed by slicing and ultrasound and incubated at 25°C.

^aORAC–Oxygen radical absorbance capacity; TRAP–Total radical trapping parameter assay; FRAP–Ferric reducing antioxidant power; CUPRAC–copper reduction assay; TEAC–Trolox equivalent antioxidant capacity assay; TOSC–Total oxidant scavenging capacity; PHOTOCHEM–Photochemiluminescence

^b+, ++, +++ = desirable to highly desired characteristic

^c−, − −, − − − = less desirable to highly undesirable based upon this characteristic

^dHAT = hydrogen atom transfer; SET = single electron transfer

^eThe lipophilic assay is quantified by AUC measured over a defined measuring time, and the hydrophilic assay is quantified based upon the lag phase.

^fInterassay coefficient of variation.

¹AA, Antioxidant activity (thiocyanate method), calculated as percentage of inhibition of peroxidation of linoleic acid; BHA, butylated hydroxyanisole; BHT, butylated hydroxytoluene; DDPH, α,α -diphenyl-β -picrylhydrazyl; IC₅₀, Inhibitory concentration for 50% inhibition in the reduction of oxidation; L-ORAC_FL, Lipophilic ORAC assay with fluorescein; H-ORAC_FL, Hydrophilic ORAC assay with fluorescein; OS, Oxidative stability; I, percent inhibition; A, absorbance, for measuring reducing power; TEAC, Trolox equivalent antioxidant activity.