Green Extraction Methods for Isolation of Bioactive Substances from Coffee Seed and Spent

ABSTRACT

Coffee is recognized worldwide as a top beverage owing to its several associated health benefits mediated by a complex mixture of unique bioactive substances. Chlorogenic acids are the key components of the phenolic fraction in green coffee seeds, accounting for up to 14% of the dry matter. The manufacturing of decaffeinated coffee demands efficient caffeine extraction from seeds and spent without solvent history effect for safety considerations. This has prompted researchers to investigate eco-friendly and cost-effective extraction technologies. Current extraction processes are not environmentally sustainable and have harmful consequences on humans. To date, developing a single standard method for effective extraction of certain complex compounds from coffee seeds remained a challenging procedure. The current review aims to give updated technical information regarding coffee plant green extraction methods, their advantages and disadvantages, and factors affecting efficacies for the recovery of bioactive compounds in coffee seeds and coffee spent. A comparative review of the uses of innovative green extraction techniques for coffee bioactive substances is introduced to present alternatives to conventional extraction methods. The most interesting finding was that the maximum total extractions of catechin (50.6 g/100 g) and caffeine (46.2 g/100 g) were achieved with enzymes in pressurized liquid extraction (PLE), and PLE-assisted with enzymes exhibited an enhancement in total phenolics and overall antioxidant compared to 50% hydro-ethanolic solutions. In addition, it has been claimed that the ultrasonic extraction can cut extraction time by 37% and temperature by 13%. These green extraction techniques represent favorable approaches to the exploitation of coffee chemicals as bioactives to explore their wide-reaching applications at an industrial level and for their valorization.

KEYWORDS:

• Microwave-assisted extraction
• caffeine
• polyphenol
• pressurized liquid extraction
• supercritical fluid extraction
• ultrasound-assisted extraction

List of abbreviations

ABTS: 2,2 -azino-bis(3 ethylbenzothiazoline-6-sulfonic acid

CDOA: caffeoyl-2,7-anhydro-3-deoxy-2-octulopyranosic acid

CGA: chlorogenic acids

CGL: chlorogenic acid lactones

pCoFQA: p-coumaroylferuloylquinic acids

pCoQA; p-coumaroylquinic acids

dipCoQA: di-p-coumaroylquinic acids

pCoCQA: p-coumaroylcaffeoylquinic acids

pCoDQA: p-coumaroyldimethoxycinnamoylquinic acids

CQA: caffeoylquinic acids

diCQA: dicaffeoylquinic acids

CQL: caffeoylquinic-1,5-lactone

DPPH: 2,2-diphenyl-1-picrylhydrazyl

DCQA: dimethoxycinnamoylcaffeoylquinic acid

DFQA: dimethoxycinnamoylferuloylquinic acid

DQA: dimethoxycinnamoylquinic acids

FCQA: feruloylcaffeoylquinic acids

FQA: feruloylquinic acids

diFQA: diferuloylquinic acids

GAE: gallic acid equivalent

GRAS: generally recognized as safe

HBA: hydrogen bond acceptor

HBD: hydrogen bond donor

MAE: microwave-assisted extraction

MIC: minimum inhibition concentration

NADES: natural deep eutectic solvent

OHC: oil holding capacity

PCE: powdered curcuminoid-rich extract

PHWE: pressurized hot water extraction

PLE: pressurized liquid extraction

SAS: supercritical antisolvent processes

SCG: spent coffee ground

SCQA: sinapoylcaffeoylquinic acid

SFE: supercritical fluid extraction

SWE: subcritical water extraction

TEO: turmeric essential oil

TFC: total flavonoid content

TPC: total phenolic content

UAE: ultrasonic-assisted extraction

UMAE: ultrasonic-microwave-assisted extraction

WHC: water holding capacity

Disclosure statement

No potential conflict of interest was reported by the author(s)..