Insoluble-Bound Phenolics in Food

Abstract

Abstract:This contribution provides a review of the topic of insoluble-bound phenolics, especially their localization, synthesis, transfer and formation in plant cells, as well as their metabolism in the human digestive system and corresponding bioactivities. In addition, their release from the food matrix during food processing and extraction methods are discussed. The synthesis of phenolics takes place mainly at the endoplasmic reticulum and they are then transferred to each organ through transport proteins such as the ATP-binding cassette (ABC) and multidrug and toxic compound extrusion (MATE) transporter at the organ's compartment membrane or via transport vesicles such as cytoplasmic and Golgi vesicles, leading to the formation of soluble and insoluble-bound phenolics at the vacuole and cell wall matrix, respectively. This part has not been adequately discussed in the food science literature, especially regarding the synthesis site and their transfer at the cellular level, thus this contribution provides valuable information to the involved scientists. The bound phenolics cannot be absorbed at the small intestine as the soluble phenolics do (5%-10%), thus passing into the large intestine and undergoing fermentation by a number of microorganisms, partially released from cell wall matrix of foods. Bound phenolics such as phenolic acids and flavonoids display strong bioactivities such as anticancer, anti-inflammation and cardiovascular disease ameliorating effects. They can be extracted by several methods such as acid, alkali and enzymatic hydrolysis to quantify their contents in foods. In addition, they can also be released from the cell wall matrix during food processing procedures such as fermentation, germination, roasting, extrusion cooking and boiling. This review provides critical information for better understanding the insoluble-bound phenolics in food and fills an existing gap in the literature.

Phenolic Composition and Evaluation of the Antimicrobial Activity of Free and Bound Phenolic Fractions from a Peruvian Purple Corn (Zea mays L.) Accession

“…Bound phenolic compounds are not absorbed in the small intestine because they are ester‐linked to cell wall polysaccharides; they then enter the colon where they undergo fermentation by the colon microbiota giving rise to potentially absorbable metabolites (Shahidi and Yeo ). An in vivo animal study has shown that rat colonic microflora exhibit esterase activity that releases certain ferulic acid derivatives from dietary cereal bran which is later partially absorbed and then enters the circulatory system (Andreansen and others ).…”

“…In general, the predominant phenolic acids in cereal grains such as corn are mostly hydroxycinnamic acid derivatives, which are found in insoluble bound forms linked to cell wall polysaccharides (Dewanto and others ; Guo and Beta ). This bound phenolic fraction is not absorbed in the small intestine and it reaches the colon where it is partially released by colon microbiota leading to a myriad of health benefits (Shahidi and Yeo ). In our previous study, the Peruvian purple corn accession AREQ‐084 had the highest total phenolic contents in its free and bound forms along with high total anthocyanin contents among different purple corn accessions (Huaman‐Alvino and others ).…”

Efeito do déficit hí­drico e CO₂ elevado sobre substâncias fenólicas e ligninas do sorgo var. 'BRS 330'

“…Os ácidos fenólicos solúveis ocorrem no vacúolo, conjugados ou não conjugados a outras substâncias. Existem também ácidos fenólicos insolúveis, que se encontram ligados à parede celular (Acosta-Estrada et al, 2014;Shahidi & Yeo, 2016). As concentrações dos ácidos fenólicos variam no mesmo órgão da planta e entre órgãos de uma mesma espécie.…”

“…A biossíntese de ácidos fenólicos solúveis e insolúveis se realiza no retículo endoplasmático; em seguida, são transferidos por vesículas de membranas para o vacúolo ou parede celular (Shahidi & Yeo, 2016). Os ácidos p-cumárico e ferúlico são os ácidos fenólicos majoritários da parede celular primária das gramíneas, o maior grupo do clado Commelinídea.…”

“…Em geral, a proporção de H é menor que a de G e S; nas gramíneas, H ocorre em proporção ligeiramente maior (Miedes et al, 2014). A lignina e os carboidratos estruturais representam importante defesa química de resistência a danos de raios UV e ataques de enzimas de patógenos e herbívoros, contribuindo para a recalcitrância da parede celular (Shahidi & Yeo, 2016).…”