FACULTY OFAGRICULTURE & ENVIRONMENT

Sorghum Malting for Future Foods

Department of Plant and Food Sciences

Tom Roberts, Senior Lecturer

Acknowledgements

› Dr Meredith Wilkes (former Lecturer now at Baiada Poultry)

› Briony Young (former BScAgr 4th-year student)

› Ali Khoddami (PhD student)

› Assoc. Prof. Peter Selle (Faculty of Veterinary Science)

Thanks to:

› O’Brien beers made from sorghum and millet.

› http://lactosesintolerances.blogspot.com.au/2014/01/gluten-free-beers.html

Sorghum Grain as a Food Ingredient in Australia

› Whole grain cereals (73%) [wheat (39%), rye (12%), sorghum (11%), oats (11%)], sugar, rice (7%), puffed wheat, barley malt extract, wheaten cornflour, coconut (1.5%), salt, honey (0.5%), vegetable oils, vitamins [niacin, thiamin, riboflavin, folate, vitamin E (contains soy)], mineral (iron).

Sanitarium Multi-Grain Weet-Bix.

http://www.sanitarium.com.au/products/breakfast/weet-bix/multi-grain

A tiny proportion of sorghum grown in Australia is used in human food.

Sorghum as a Crop

› Sorghum bicolor is one of the most important food and animal feed crops in arid and semi-arid regions of the world.

› There are many potential economic, environmental and social benefits if utilised as a food grain in the Western world.

› Starch digestibility is limited – attractive for obesity sufferers.

› Gluten-free; i.e. safe for consumption by sufferers of Coeliac disease.

Sorghum grain head.

http://www.plantzafrica.com/plantqrs/sorghum.htm

Sorghum grain: a vital food for millions across parts of Africa and Asia.

Sorghum-based Foods in the Developing World

› Breads

› Porridge

› Couscous

› Tortillas

› Cookies

› Kunun-zaki (non-alcoholic Nigerian beverage)

› + Beer (of course) – a food?

Sorghum porridge.

http://www.zimbokitchen.com/mabela-sorghum-porridge-mapfunde/

Foods made primarily from sorghum are uncommon in the Western world.

Sorghum as a Australian Commodity

In Australia, sorghum ranks 7th in production but not in top 20 in value.

Sorghum in Australian Crop Production

Sorghum is a relatively low-value crop in Australian agriculture.

Australian Bureau of Statistics.http://www.abs.gov.au/ausstats/

Physiological Advantages of the Sorghum Plant

› Sorghum has Kranz anatomy.

› Compared to other cereals (C3), such as barley, sorghum has:

- excellent drought tolerance

- excellent heat resistance

- excellent water-use efficiency

Transverse section of sorghum leaf.http://hdl.handle.net/102.100.100/2680

Sorghum is a C4 plant adapted to tropical conditions.

The Genetic Diversity of Sorghum

› 17 of the 25 recognised Sorghum species are native to Australia.

Sorghum halepense, Pers. "Evergreen Millet"

Maiden, Joseph Henry (1898). Manual of Grasses New South Wales

Australia is the natural centre of diversity for the Sorghum genus.

Worldwide distribution of sorghum taxa

http://www.cwrdiversity.org/conservation-gaps/

Sorghum vs Barley Grain Anatomy

The storage proteins of sorghum grain (kafirins) are more hydrophobic than other cereal prolamins.

- Thus the endosperm is relatively impermeable to water and therefore resistant to breakdown by hydrolytic enzymes released from the aleurone.

Young, B. (2011). BScAgr 4th-year thesis.

The Basics of Malting

› Malting is the process of steeping, germinating and drying (kilning) cereal grains to promote the development of hydrolytic enzymes that are otherwise absent in ungerminated grains.

› Malting produces grains with a profoundly different flavour compared to unmalted grain.

Bamforth (1998). Beer: Tap into the Art and Science of Brewing. Prenum Press (New York)

Malting involves steeping, germinating and kilning.

Malt as a Food Ingredient

› Dough leavening

› Softening and moisture retention of bakery crumb

› Browning of bakery crust

› Addition of colour

› Aroma and flavour enhancement

› Texture improvement and nutrition enrichment

Western food and beverage products containing barley malt.

Malt has multiple functions as a food ingredient.

Sorghum Malting: Adding Value

› Enzyme levels, particularly amylase activities, are low.

› Starch gelatinisation temperatures are high (compared to those of barley).

› As a result, malt extract (fermentable sugar) levels are frequently low.

Well-established barley malting protocols cannot be directly applied to sorghum.

Sorghumpeak viscosity = 1331 cP

Wheatpeak viscosity = 996 cP

Properties of Sorghum Malt

› It’s no good producing sorghum malt if it is unpalatable!

› We want the health advantages of the phenolics without excessively bitter taste (mainly due to tannin).

› The development of white and yellow sorghum varieties has helped in the production of flours which do not develop unwanted colours and flavours in food products.

› Overall, sorghum should be considered as a functional food ingredient.

What is the flavour of sorghum malt?

Phytochemicals in Sorghum Grain

› Sorghum grain contains phenolic acids and flavonoids.

› Australian sorghums do not contain condensed tannins (made via the condensation of flavans). Thus they do not have a pigmented testa and are classified as Type I sorghums.

Phytochemicals in sorghum grain are dominated by phenolics.

Phytochemicals in Sorghum Grain

› Epidemiological evidence suggests that sorghum consumption reduces the risk of certain types of human cancers compared to other cereals (Awika & Rooney, 2004).

- The high concentration of phytochemicals in sorghum may be partly responsible.

› Sorghum phytochemicals promote cardiovascular health in animals.

Gluten-free malt extract.

http://www.love2brew.com/Sorghum-Liquid-Malt-Extract-3-3-lb-Briess-p/lme012.htm

Some phytochemicals in sorghum may have benefits to human health.

Phytochemicals in Sorghum Grain

› From Taylor and Duogo (2014) J Sci Food Agric:

“The food-processing operations applied to these grains, i.e. dehulling and decortication, malting, fermentation and thermal processing, drammatically affect the quantity of phenolics present, most generally lowering them.”

› Ali Khoddami’s work shows that malting of Australian cultivars of sorghum increases (a lot!) the concentrations of various classes of phenolic compounds.

What happens to sorghum phytochemicals upon malting?

Ali Khoddami’s PhD Research - Poster

› Four Australian sorghum cultivars:

- Dominator (Nuseed)

- G22 (Pioneer)

- G99 (Pioneer)

- G56 (Pioneer)

› Compared unmalted and malted grain:

› Total phenolics

- Spectrophotometric method

› Antioxidant activity

- DPPH and ABTS methods

› Specific phenolics

- HPLC and mass spectrometry

- Anthocyanins

- Flavan-4-ols

- 3-deoxyanthocyanins

Effect of malting on anthocyanin compounds and antioxidant activity in Australian sorghums.

Potential of Sorghum Malting

› A commercial sorghum malting industry is yet to be developed in Australia.

› Malting of sorghum on a commercial scale will help to develop a sustainable demand for a hardy summer crop.

› With greater diversity of sorghum products, a reliable income stream may be retained during periods where production of less hardy crops may not be feasible.

Malting of Sorghum has Potential to Produce Food Ingredients

A Future for Australian Sorghum Malting

Several important aspects need to be considered in the screening of sorghum varieties for quality malt production.

Young, Briony. (2011). BScAgr 4th-year thesis.

Ideas for Western Food Products Containing Sorghum

› Snacks (e.g. muesli bars) - whole grains

› Infant foods - increase antioxidant levels

› Multi-grain porridges – where sorghum would not act as a thickening agent (c.f. oats)

- Based on high gelatinization temperature of sorghum

› Puffed (popped?) sorghum

› Fractured grain (not flour) in breadPuffed sorghum (produced by Woods Foods).

http://www.woodsfoods.com.au/puffed-sorghum/

The functionality and low cost of sorghum are its advantages.

Thank you!

Questions? Comments?

https://www.agric.wa.gov.au/waterlogging/summer-crops-reduce-waterlogging