Influence of four different coagulants on the physicochemical properties, textural characteristics and flavour of tofu

Abstract

Summary The coagulation mechanism and quality characteristics of tofu depend on the choice of coagulant. The effects of using magnesium chloride (MgCl2), calcium sulphate (CaSO4), glucono‐δ‐lactone (GDL) and fermented soybean whey (FSW) as coagulants for tofu were investigated using solid‐phase microextraction (SPME), two‐dimensional gas chromatography coupled with mass spectrometry (GC×GC‐MS), scanning electron microscopy (SEM) and analysis of textural characteristics and physicochemical properties. Results showed that GDL tofu exhibited the highest yield (202 g 100 g−1) and moisture content (76.3%). FSW tofu had the highest protein content (18.5%), amino acid content (15.85%) and textural properties. GC×GC‐MS analysis revealed the number of 49, 44, 55 and 63 flavour substances, respectively. In sensory evaluation tests, GDL tofu was reported to possess a smooth surface and white colour. The microstructure of FSW tofu was dense and uniform. Through the above technical researches, the study suggested FSW gave tofu the best quality, more unique flavour and more potential popular among consumers.

Grape Pomace as a New Coagulant for Tofu Production: Physicochemical and Sensory Effects

“…There are two major steps in tofu production: heating soymilk and coagulation of soymilk to obtain a curd [1,6].…”

“…The physical, textural, and sensory properties of the obtained tofu are affected by multiple factors that can be classified as intrinsic (i.e., composition of soya seeds) and extrinsic (i.e., processing conditions and packaging) factors [11][12][13]. The most critical step in the processing is the coagulation phase, which involves the selection of a coagulant [6,[14][15][16]. At present, common coagulants are divided into three main groups: acids, salts, and enzymes [6,13].…”

“…The most critical step in the processing is the coagulation phase, which involves the selection of a coagulant [6,[14][15][16]. At present, common coagulants are divided into three main groups: acids, salts, and enzymes [6,13]. The driving forces behind the acid gelation of soy proteins are isoelectric precipitation, including salt bridging, and direct interactions, such as hydrogen bonding and van der Waals forces [8,16].…”

“…The driving forces behind the acid gelation of soy proteins are isoelectric precipitation, including salt bridging, and direct interactions, such as hydrogen bonding and van der Waals forces [8,16]. With salts, a three-dimensional network structure is formed by forming salt bridges to cross-connect protein molecules [6]. In particular, phytic acids interact with Ca 2+ to form non-ionising products that allow interactions between Ca 2+ and proteins.…”

“…Enzyme coagulants such as transglutaminase can assemble proteins with the help of isopeptide bonds that are formed from the amine group in the glutamine residue and the ξ-amino group in the lysine residue [11]. Fermented soy whey, glucose-delta-lactone (GDL), and citric acid are commonly used acidic coagulants [6,14,16,18], while calcium sulphate, calcium chloride, calcium acetate, calcium lactate, and magnesium chloride are commonly used salt coagulants [5,19]. Magnesium chloride allows the taste of soybean to be retained and creates a more natural flavour for tofu; however, it is a quick-acting coagulant with a lower yield, forming a harder and non-uniform tofu [5].…”