The Effect of Microwaves on Essential oils of White and Black Pepper (Piper nigrumL.) and their Antioxidant Activities

Abstract

White and black peppers were subjected to conventional roasting as well as microwave heating in order to study the effects of such techniques on the volatile constituents of each spice oil and its antioxidative activity. Hydrodistillation oil of each spice was analyzed using Gas Chromatography (GC) and Gas chromatography-Mass spectrometry (GC-MS). Twenty six compounds were identified in essential oil of white pepper, whereas, twenty compounds were detected in black pepper essential oil. δ-Carene, limonene, αand β-pinene and β-caryophyllene were the major components in both. Due to heating treatments, increase in sesquiterpenes and drastic increase in oxygenated terpenes were observed in comparison to the raw samples. Such changes affected the antioxidant activity of the treated samples using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging as well as β-carotene bleaching test against tert-Butylhydroquinone (TBHQ).The strongest effect for reduction of DPPH radical was by white pepper microwave heated sample which exhibit 78.2 % ± 2.1), followed by conventionally roasted black pepper sample, (75.2 % ± 1.9) compared to TBHQ (98.8 % ± 2.1) at the same concentration 400 μg/ml. However, conventionally roasted black pepper recorded the highest inhibiting effect for the oxidation of linoleic acid and the subsequent bleaching of βcarotene (78.2 % ± 2.3), followed by white pepper microwave heated sample (76.2 % ± 1.9) in comparison to TBHQ (98.8 % ± 2.1).

Effect of Microwaves on Essential Oils of Coriander and Cumin Seeds and on their Antioxidant and Antimicrobial Activities

“…3). In our previous study we proved that microwave heated samples of HD oregano leaves essential oil have the stronger antioxidant effect for reduction of DPPH radical and bleaching of β-carotene than conventionally roasted samples due to the higher percentages of two major isomeric phenols carvacrol and thymol and their biosynthetic precursors γ-terpinene and p-cymene in microwave heated sample (44.5 %) than in conventionally roasted sample (33.7 %) 46 , also we proved that α and β-pinene, compher and camphene may attribute to antioxidant activity of black pepper oil 47 . In our previous study we proved that microwave heated samples of HD oregano leaves essential oil have the stronger antioxidant effect for reduction of DPPH radical and bleaching of β-carotene than conventionally roasted samples due to the higher percentages of two major isomeric phenols carvacrol and thymol and their biosynthetic precursors γ-terpinene and p-cymene in microwave heated sample (44.5 %) than in conventionally roasted sample (33.7 %) 46 , also we proved that α and β-pinene, compher and camphene may attribute to antioxidant activity of black pepper oil 47 .…”

Antimicrobial effect of black pepper petroleum ether extract for the morphology of Listeria monocytogenes and Salmonella typhimurium

“…Plant extracts and secondary metabolites possessed antifungal, antiviral, or antimicrobial activities. The main constituents of black pepper were piperine and volatile oils (Abd El Mageed et al 2011). High Performance Liquid Chromatography analysis revealed that piperine, piperidine, eugenol, and catechin were constituents of Piper nigrum crude extract (Jin et al 2013).…”

Effect of Microwave Treatment on the Profile of Volatile Compounds and Characteristics of White Pepper (Piper nigrum L.) Essential Oil

“…Piperine is the main component that causes edible flavor in pepper (Nitin et al 2012). Pepper essential oils have potential for biopesticide agent (Abdullah et al 2020), antibacterial agent (Abdallah & Abdalla 2018), analgesic (Costa et al 2016), and natural insecticide (Chaubey, 2017), as well as antioxidant activity (Gülçin, 2005;Abd El Mageed et al 2011).…”