PROBLEM TO BE SOLVED: To provide novel food materials derived from plant secondary cell walls.SOLUTION: A plant cell in which a primary cell wall is removed or crushed with cellulase is heated in an environment of pH 2.5 to 3.5. Then, an insoluble matter is removed by centrifugation or the like to obtain a solution which is a solubilized product according to the present invention. Furthermore, after removing the insoluble matter, it may be recovered as a precipitate by cooling, thawing after freezing, salt precipitation or the like to obtain a solubilized product according to the present invention. The solubilized product has excellent emulsifying action and foaming property and can be used as an emulsifying agent. In addition, since it is also a solubilized product of pectin, it can be used as various food materials as prebiotics.SELECTED DRAWING: Figure 6【課題】植物二次細胞壁由来の新規食品素材を提供する。【解決手段】一次細胞壁をセルラーゼで除去し又は破砕した植物細胞を、pH2.5~3.5の環境下で加熱する。その後、不溶物を遠心分離などにより除去した溶液を本発明に係る可溶化物とする。また、さらに、不溶物を除去した後に、冷却や凍結後の解凍、塩析などの方法により沈殿物として回収し、本発明に係る可溶化物としてもよい。当該可溶化物は優れた乳化作用や起泡性を有し乳化剤として利用できる。また、ペクチンの可溶化物でもあるため、プレバイオティクスとして種々の食品素材としても利用できる。【選択図】図6