114 S. Bolwig et al.
6.4 Technical options for spent grain use
Organic waste is defined here as ‘biodegradable waste from gardens and parks,
food and kitchen waste from households, restaurants, caterers, hotels and
retail premises and similar waste from food processing’ (Jürgensen & Confalonieri, 2016, p. 3). However, brewers’ spent grain is not a waste product but
the main side- stream from the beer brewing process and represents approximately 85% of all organic by- products from brewing. A large volume of spent
grain is generated by the brewing process, around 20 kg per hectolitre of beer
produced (Aliyu & Bala, 2011; Mussatto, Dragone & Roberto, 2006), and it
is available all year round and at a low cost (Buffington, 2014).
In the wider context of sustainable production, these properties, together
with its biophysical and nutritional attributes, have stimulated interest in
adding value to spent grain, and numerous laboratory experiments have been
performed with this objective in mind. These studies have been recently
reviewed (Aliyu & Bala, 2011; Mussatto, 2014; Thomas & Rahman, 2006),
revealing a great diversity in potential processes and products. Figure 6.1
shows the technical processes through which spent grain can be transformed
into different product types (marked in bold), i.e. human food, animal feed,
Figure 6.1 Technical processes and products based on spent grain.
Source: Adapted from Buffington (2014) and van Wyk (2001)