Later this spring, Professor David Mabberley, the authority behind botanical bible Mabberley’s Plant Book, is running a two-day short course linked to the Santos Museum of Economic Botany in Adelaide Botanic Garden. The topic is Economic Botany Today: A study of practical ecological biochemistry for humans. The topic is hardly an esoteric one; as we take our daily close encounters with the plant kingdom for granted, you might miss the basic premise. Plants harvest sunlight and utilise the harvested chemical energy to metabolise the substrates of our food, textiles, medicines, drugs, dyes, pesticides and perfumes. The exploration of this relationship is a rich field and Mabberley one of the world’s great guides.
While photosynthesis and plant biochemistry provide the foundations, human manipulation of these biochemicals demonstrates remarkable ingenuity. Perhaps the outstanding exemplar to explore the astonishing sophistication of our manipulation is beer. Beer’s ingredients are simple – water, barley, hops and yeast. Indeed, in Germany, a beer purity law dating from 1516, Reinheitsgebot, requires beer to be made only from water, malt and hops. The rider to this is the recognition of yeast – an essential ingredient in beer-making utilised effectively but unknown 500 years ago. The finessing of beer production over the past 500 years illustrates some remarkable advances in biotechnology. Nick Sterenberg, Coopers’ operations manager, argues that beer has actually driven advances in biotechnology, especially over the past century – and there’s strong evidence behind Sterenberg’s claim. (I’ll see if I can get Nick to guest in this column – or maybe even better, for me, to ghost!)
The first step in beer making is selecting and growing the grain. Adelaide Botanic Garden’s Navigator barley crop represented the talents of barley breeder Jason Eglinton (University of Adelaide’s Waite Campus) and Rob Wheeler (SARDI) in sowing, growing and harvesting. Barley, Hordeum vulgare, is singularly fashioned for brewing – strains such as Navigator take that fashioning to a molecular level. Barley has three layers of aleurone cells underneath the seed coat (wheat and maize have only one) – the aleurone layer plays an active role in germination. This contributes to rapid germination and facilitates synchronous malting and to the breakdown of cell walls.
The Gardens’ barley was malted by Joe White Maltings – a generous favour as our quantity was too small for commercial malting and too large for the lab bench. The high temperatures required for kilning to stop germination to complete the malting process, and required again for the mashing process, mean that the amylases (the enzymes that break down the starch in the seed endosperm into sugars) must be heat tolerant. Remarkably, barley amylases survive kilning and mashing to break down starch into sugars – a critical step in brewing. Further, while the barley protein content must be low for decent beer, there needs to be just enough protein to support colour and foam, and to feed the yeast.
So far, we’ve selected and grown a malting barley, and malted and mashed the grain to prepare the wort – a sugar-rich substance whose flavours are essentially derived from a very sophisticated manipulation of barley. The wort is sterilised and the remaining enzymes inactivated by boiling. At this stage, hops are added for flavour, bitterness and aroma, and as a preservative. While ale and beer are now largely synonymous, historically beer was ale made with hops – the superiority of hops to alternative bitter herbs for both taste and preserving beer has been apparent since at least the 1516 Reinheitsgebot. So superior that I’m not even going to discuss the alternatives.
Botanically, hops, Humulus lupulus, are exceptional. Hops are dioecious – with separate male and female plants; only the latter produce the catkins (‘hop cones’) that are utilised in brewing. In spring, the roots of the hops send up bines around a support commonly trellised up to eight metres. Bines are climbing plants that grow by extending as a helix, contrasting with vines that utilise tendrils or suckers. Hop bines insist on wrapping clockwise. The plants themselves used to be grown in the Adelaide Hills (Lobethal Bierhaus’s Alistair Turnbull lives in a retired oast house near his brewery). Today commercial hop production in Australia is restricted to Tasmania and north east Victoria. Harvest requires the bines to be pulled down and the flowers dried and then pressed (take a look at the Horst Ranch hop films from the 1900s to illustrate the mechanisation of this process here). Hops contain over 250 named compounds including oils such as the yellowish waxy oleoresin lupulin that give flavour and aroma, and the antibiotic priorities that suppress bacteria and favour brewer’s yeast.
The final stage of beer making is the introduction of brewer’s yeast for fermenting – converting carbohydrates to alcohol and carbon dioxide. The yeast is commonly Saccharomyces cerevisiae – the official state microbe for Oregon in the United States. S. pastorianus is commonly utilised for lager beers. The Carlsberg Laboratory, founded by the Carlsberg Brewery in 1875, has made, and continues to make, major contributions to biochemistry and biotechnology (but we’re leaving that arena for Nick).
To understand the sophistication of our relationship with plants, you should sign up for Professor Mabberley’s course and endeavour to try the Botanic Ale that’s currently being brewed from the Adelaide Botanic Garden barley crop. The support of Coopers and Lobethal Bierhaus has made Botanic Ale possible – so if you can’t get Botanic Ale, their beers will more than suffice. You just have to think about the series of genetic miracles and the sophisticated craft that make them possible.
Originally published in The Adelaide Review on 1 September 2014.