A tragic tofu tale?
By Amen Seo
Whether you love it or hate it (like my partner's mum who silently shifted all the tofu pieces to the side of her plate the first time I cooked her a meal), global tofu consumption is rising. In fact, driven by veganism/vegetarianism on both sides of the Atlantic, tofu has found a growing role as meat substitute. (Much to the disgust of the omnivores who think the pseudo similarities between real meat and tofu variants are deceptive and evil). However, it’s a shame tofu has been unfairly pigeon-holed in the West in this way, because tofu has been enjoyed as a food in its own right, in endless varieties and forms, as a staple of East Asian diets for millennia. Low in calories, dense in protein and iron-rich, its subtle flavour and variations of texture lend infinite versatility to both sweet and savoury dishes.
Not to mention the lower carbon footprint of soybeans 'per kg produced', when compared to meats. More than 25% of global greenhouse gas emissions come from food production, with over half (16.5%) coming from animal agriculture. While there is some controversy on the environmental impact of soybeans - for instance, the de-forestation of Brazil driven by growing soybean demand, the picture is further complicated when it is taken into account that approximately 75% of all global soya produced is used to feed livestock.
Regardless of polarised opinions about tofu, some are predicting that the global tofu market will increase 5% annually in the next few years, with Europe being the fastest growing market, inversely related to its declining meat consumption. With the climate emergency hot on our heels, we think the rise of tofu is no bad thing.
Tofu is bean curd, made by coagulating soy milk from ground soybeans. The curds can be pressed into blocks of varying firmness – extra soft, soft/silken, firm, extra firm, and further processed into many other forms, by pickling, freeze drying, etc.
The flavour, quality, and texture of tofu is significantly influenced by the processing parameters, and coagulation which emulsifies the protein and oil suspended in the boiled soy milk, and is the most crucial step in tofu production.
Magnesium or calcium salts are added as coagulants: magnesium chloride (also called Nigari, used in Japanese-style tofu), calcium sulphate (also known as gypsum, used in Chinese-style tofu) or calcium chloride (mostly used in the US). Coagulants typically make up 1.5-5% of the soy milk quantity, and the mixture is heated to between 60-90°C.
The coagulation process is affected by many variables which must be carefully controlled: which coagulant is used, the variety of the soybeans, the pre-treatment of soybeans, the percentage of protein in the soybeans, slurry cooking temperature, coagulation temperature, stirring time after adding the coagulant, and moulding of tofu.