Protein hydrophobic dressing on seeds aiming at the delay of undesirable germination

Abstract

Polymer seed-coatings have been largely tested as an alternative method for preventing diseases and have the potential to be used to control undesirable germination and thereby increasing seed storage. Amongst these, the protein-based coatings can be applied with advantage of forming stable biodegradable and hydrophobic films. Due to their chemical structure, protein dressings act as efficient barriers for water uptake, even when seeds are unavoidable exposed to a moist environment. In this work, the effect of hydrophobic dressings was tested on the germination rate of sugar beet (Beta vulgaris L.) and broccolis (Brassica oleraceae var italic L.) seeds under laboratorial condition. Zein, natural maize (Zea mays L.) proteins extracted from gluten meal, was used as precursor polymers to form the coatings. Seeds were dressed by direct submersion into a zein/ethanol formulation of zein concentration of 3.0 g L -1 , followed by natural air drying. The resultant coating has elevated the hydrophobic feature due to the high content amino acids present in the structure of the zein. For both types of seeds an overall delay in sprouting and germination was observed, with a more accentuated reduction on sugar beet germination percentage after eleven days of measurements. The effect on germination rates is understood as the efficiency of the zein coating to form a physical barrier preventing water permeation into the seeds. Key words: seed dressing, undesirable germination control, protein coating, seed storage COBERTURA HIDROFÓBICA A BASE DE PROTEÍNAS SOBRE SEMENTES VISANDO A REDUÇÃO DE GERMINAÇÕES INDESEJÁVEISRESUMO: Filmes com características hidrofóbicas baseados em proteínas foram avaliados como revestimento em sementes de beterraba e brócolis, com o objetivo de prevenir germinações prematuras pela redução na absorção de água. Zeínas, proteínas naturais extraídas do glúten de milho, foram empregados como polímeros precursores na elaboração das soluções de cobertura. Os revestimentos se deram pela completa imersão das sementes em formulação zeínas/etanol na concentração de 3,0 g L -1, seguidos de secagem ao ar. Os filmes resultantes apresentam elevada natureza hidrofóbica como resultado do alto teor de amino ácidos presentes na estrutura dessas proteínas. Para ambas as sementes testadas, os resultados apontam um atraso no período de geminação, sendo mais acentuado na porcentagem medida para a beterraba após o período de 11 dias. As diferenças entre as taxas de germinação são discutidas em termos da ação do filme como barreira física reduzindo a permeação de água para o interior das sementes. O estudo demonstra potencial aplicação de zeínas como substrato na redução de germinações indesejáveis durante estocagem em substituição a polímeros usualmente empregados para este fim. Palavras-chave: revestimento de sementes, controle de germinações indesejáveis, coberturas de proteínas, conservação de sementes.

REVIEW: Zein Extraction from Corn, Corn Products, and Coproducts and Modifications for Various Applications: A Review

“…Being mostly nonpolar in nature, zein films have been explored for coatings in numerous food applications. Broccoli and sugar beet seeds germinated later and more slowly when dressed with a light zein coating (Assis and Leoni 2009. Both the zein film and polyethylene films allowed retention of broccoli firmness and color after six days in refrigerated storage; broccoli in zein-only films lacked off-smells.…”

“…Zein coatings have even been considered as a means to control undesirable seed germination. Broccoli and sugar beet seeds germinated later and more slowly when dressed with a light zein coating (Assis and Leoni 2009. The slow germination was attributed to the coating preventing moisture permeation.…”

1h NMR Investigation of Oil Oxidation in Macadamia Nuts Coated With Zein-Based Films

“…Among these proteins, the maize ( Zea mays ) storage‐protein zein is suitable for formulating shiny edible coatings. Zein coatings have previously been used to delay undesirable germination in crops (Assis and Leoni 2009) and to extend the storage life of tomatoes (Park et al . 1994), broccoli (Rakotonirainy et al .…”

“…Among these proteins, the maize (Zea mays) storage-protein zein is suitable for formulating shiny edible coatings. Zein coatings have previously been used to delay undesirable germination in crops (Assis and Leoni 2009) and to extend the storage life of tomatoes (Park et al 1994), broccoli (Rakotonirainy et al 2001) and apples (Bai et al 2003). Others have suggested using the coatings as a grease barrier on nuts (Andres 1984;Trezza and Krochta 2002;Wambura et al 2008).…”

Extraction of zein from corn co-products

“…Zein coatings have even been considered as a means to control the undesirable germination of seeds. Broccoli and sugar beet seeds germinated later and more slowly when dressed with a light zein coating (Assis and Leoni 2009). The slow germination was attributed to the coating preventing moisture permeation.…”