Study on volatile compounds formed by thermal reactions of enzymatically hydrolyzed proteins of mung bean, pea and soybean with reducing sugars

Abstract

The demand for plant-based proteins as substitutes for animal proteins is rapidly increasing. Notably, enzymatically hydrolyzed vegetable protein (EVP) has been reported to exhibit enhanced functional properties, such as gel-forming ability and water retention, along with antioxidant and antimicrobial effects. In this study, the characteristics of three types of EVP, including mung bean, soybean, and pea, were analyzed, and the volatile compounds resulting from the Maillard reaction were explored based on the type of EVP and the reducing sugar. To elucidate the generation pathways of volatile compounds, mung bean, soybean, and pea were hydrolyzed using the enzymes alcalase and flavourzyme. The degree of hydrolysis of each EVP was measured using the Formol titration method. Molecular weight distribution was analyzed via gel permeation chromatography, and free amino acid analysis was conducted using high-performance liquid chromatography. Volatile compounds were extracted using solid-phase microextraction and analyzed by gas chromatography-mass spectrometry. Principal component analysis revealed that the type of EVP and reducing sugar contributed to the differentiation of the samples. In terms of the influence of sugars, the glucose model contributed to the formation of aldehydes and ketones, while the fructose model tended to generate pyrazine compounds. The amino acid composition of each EVP varied, affecting the formation of volatile compounds. Mung bean and pea, which had high amino acid contents, produced significant amounts of Strecker aldehydes and heterocyclic compounds, such as 3-methylbutanal, 2-methylpyrazine, 2-acetylpyridine and 1-(1H- pyrrol-2-yl)ethenone, whereas soybean predominantly generated furan compounds, including furan-2-carbaldehyde and 5-(hydroxymethyl)furan-2-carbaldehyde. This study provides insights into the degree of hydrolysis and molecular weight distribution of the three EVPs, elucidating how the differences in amino acid composition among the samples influence the generation of flavor compounds. These findings can serve as fundamental data for the application of plant-based materials in the processed food industry.;식물성 단백질은 동물성 단백질의 대체제로 점점 더 수요가 증가하고 있다. 특 히, 효소를 이용하여 가수분해한 Enzymatically hydrolyzed vegetable protein(식 물성 효소 가수분해물, EVP)은 젤 형성능이나 보수력 등 기능적 특성이 향상되고 항산화 및 항균 효과를 가진다고 알려져 있다. 본 연구에서는 3가지 EVP(녹두, 대두, 완두)의 특성을 분석하고 Maillard reaction에서 amino group을 제공하는 EVP의 종류와 carbonyl group을 제공하는 환원당의 종류(Glucose, Fructose)에 따른 향미 변화를 탐구하고자 하였다. 휘발성 향기 성분의 생성 경로를 밝히고자 Alcalase와 Flavourzyme 효소를 이용하여 녹두, 대두, 완두를 가수 분해 한 후, Formol titration method를 사용하 여 각 EVP의 Degree of Hydrolysis (DH)를 측정하였다. Gel permeation chromatography (GPC)를 이용하여 분자량 분포를 분석하였으며, High performance liquid chromatography (HPLC)를 이용하여 유리 아미노산 분석을 진행하였다. 휘발성 화합물 분석은 Solid-phase microextraction (SPME)를 사용 하여 추출하였으며 Gas chromatography-mass spectrometry (GC-MS)를 이용하 여 분석하였다. 주성분 분석 결과 EVP의 종류와 환원당의 종류에 따라 각 시료가 구분되었다. 당 영향에 있어 glucose 모델은 aldehyde 및 ketone류 화합물 구분에 기여하였 으며, fructose 모델은 pyrazine류 화합물에 기여하는 경향을 보였다. 각 EVP의 아미노산 조성은 다른 경향성을 보였으며 이는 휘발성 향미 화합물을 생성하는데 영향을 미쳤다. 아미노산 함량이 높은 녹두와 완두에서는 3-Methylbutanal, 3- methylsulfanylpropanal, 2-methylpyrazine, 2-acetylpyridine, 1-(1H-pyrrol-2- yl)ethenone 등 Maillard reaction의 주요 향미 성분인 Strecker aldehyde와 heterocyclic 화합물이 많이 생성된 반면, 대두에서는 furan-2-carbaldehyde, 5- (hydroxymethyl)furan-2-carbaldehyde 등의 furan류 화합물 생성이 우세하였다. 본 연구는 3가지 EVP의 가수분해율과 분자량 분포에 대한 특징을 밝히고 각 시료에 함유된 아미노산 차이가 향미 물질 생성에 주는 영향을 설명하여 식물성 소재를 응용하는 가공제품 분야의 기초 연구 자료로 활용될 수 있다.