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An average day (or how near infrared spectroscopy affects daily life)

Peter Flinn (Kelspec Services Pty Ltd, Dunkeld, Victoria, Australia)

Let me introduce you to Mr Jack Average. However, dear reader, in this age of political correctness I had better assure you that this story could equally be about Ms Jane Average.

Anyway, Jack is a just an ordinary bloke, living an ordinary life in the suburbs. Like many citizens, he knows little about science in general and NIR in particular, and cares less. What he does not realise is that nearly every activity in his daily life is touched in some way by the extraordinary analytical technique of NIR. Like Big Brother (but in a more tasteful and unobtrusive manner), let us “tag along” with Jack for a day and see how many applications of NIR he takes for granted.

It is the weekend, and Jack rises a little later than usual, enjoying a leisurely breakfast. He knows he should have more fibre in his diet, so he starts off with a plate of muesli. Measurement of protein, fat and fibre in processed cereal foods is a routine NIR application.1

Next, he cuts a slice of brown bread and spreads some honey on it. He gives no thought to the fact that his daily bread is made from flour, which in turn comes from wheat. Measurement of protein and moisture in wheat (and other grains) is probably the most widespread and successful NIR application in the world.2

For example, one major Australian grain handling authority, CBH Pty Ltd has almost 200 grain receival points in Western Australia alone, and owns the largest network of NIR instruments in the world. Wheatgrowers are paid on a protein-based system, possible only with the adoption of NIR. Many other grain quality indicators are routinely measured or researched using NIR, including hardness, flour yield, colour and water absorption (wheat) and malting quality (barley).3 Jack’s honey could well have been checked by NIR for quality, adulteration or botanical origin.4 He rounds off his breakfast with a cup of freshly brewed coffee, and adds a spoonful of sugar. NIR is used to measure caffeine content of coffee5 (and other beverages), and for discrimination between the two major cultivars Arabica and Robusta.6 Despite the challenges of working with a material like sugarcane, the sugar industry is now a significant user of NIR for estimating moisture, fibre and sugar (°Brix) content.7

While Jack finishes his breakfast, he reads his daily newspaper. Whilst he should not be surprised that paper is manufactured from pulped wood, he certainly would not realise that NIR research is underway to assess quality, physical and mechanical properties and even the ageing process of wood.8 Ash and dry matter content of recovered paper are important criteria in newspaper production, and on-line NIR determination of these properties is being investigated.9

Jack decides to escape suburbia for the day and take a drive in the country to visit his brother. First, he has to fill his car with fuel at his local service station, and like all motorists curses the ever-increasing price of petrol (or gas, if he is American!). Jack’s car is his pride and joy, and he worries about media reports concerning sub-standard fuel. He is also concerned about the environment, and wonders why those mad scientists don’t invent fuels from alternative (and hopefully cheaper) sources. Well, he may be interested to know that NIR is increasingly being used to monitor chemical and physical properties, such as octane number, benzene, density and sulphur, in the refining and petrochemical industries.10 There is much research in progress on the development of “biofuels” to reduce our reliance on fossil fuels, but quality control is a big issue and NIR is starting to play an important role here. NIR can also detect the level of biodiesel fuel (from vegetable oils) added to diesel. Jack Average is glad to leave the rat-race behind as he heads for the peace and fresh air of the countryside. While thinking of the environment we should remember the subject of recycling,11 where NIR has an important role to play. Parts of Jack’s car are made from recycled plastics. Jack’s brother Fred owns a dairy farm, and Jack always enjoys visiting, although he probably would not want to milk cows twice a day, every day. He arrives just as Fred is feeding out hay to his cows, and immediately is conscripted into the process. Fred is a progressive dairy farmer and would not dream of buying in hay without it being first tested for quality—naturally by NIR.12

Assessment of energy, fibre, protein, sugars and other indicators of animal performance in forage, grain and mixed feed using NIR is now firmly established across extensive and intensive livestock industries in many countries.13 It is a vital tool for the domestic and export hay market, especially in the USA and Australia. There is an increasing focus on “functional” or in vivo measurements, such as intake, preference, digestibility and even an index to indicate the danger of acidosis in ruminants fed high grain diets. NIR is also used to estimate fermentation characteristics of silage, such as pH, ammonia nitrogen and volatile fatty acids.14 Much effort is being expended to improve standardisation of feed testing methods between laboratories, and NIR is proving helpful in this challenge. Following the BSE crisis, detection of ingredients in mixed feeds, especially meat and bone meal, is a major issue, especially in Europe, and a large study has found NIR to be an important tool in discriminating between acceptable and unacceptable ingredients.15

Having fed the cows, it is now time for Fred to feed his brother. Lunch consists of barbequed steak and sausages, pasta, salad and a variety of fresh fruit, all washed down with green tea (Fred is more trendy than many dairy farmers!). Probably neither Jack nor Fred would appreciate that NIR has an important role in monitoring meat quality, not just fat, protein and water but also in screening for authenticity.16

There is some evidence that NIR can predict the tenderness of beef,17 but challenges remain, especially in sampling and sample presentation due to the heterogeneous nature of the product. Colour and cooking quality of fresh pasta can be estimated by NIR,18 and a major application is the quality assessment of intact fruit. Soluble solids (mainly sugars measured as °Brix), starch, acidity, detection of internal defects and sensory properties can be determined,19 and on-line quality sorting of fruit is being adopted.20 Green tea, common in Asia and increasingly popular in western countries, has also been analysed successfully by NIR for several components, including caffeine, amino acids, polyphenols, alkaloids and organoleptic properties.

After lunch, the two brothers embark upon a farm walk, Fred explaining to Jack all about his soils, pastures, crops and fertiliser strategies. Soil analysis by NIR, particularly for carbon, nitrogen and anions is becoming more common,21 but NIR soil mapping and discrimination of soil types have also been attempted.22

Interest is growing in in-field pasture monitoring, with a potential role for portable NIR instruments. Grass and crop on-site analysis for dry matter and nutrients, particularly in breeding trials, is a major new field of NIR research, with NIR sensors mounted on forage or grain harvesters.23 Prediction of nitrogen fertiliser requirements of crops, particularly rice and wheat, via NIR leaf tissue analysis, represents an important advance in cost-efficient application of fertiliser and has environmental benefits.24 Quality assessment and pro- cess management of organic fertilisers and compost by NIR is also gaining interest. Environmental applications in general, involving the sampling and testing of manure, slurries, sewage, lake sediments and other biosolids for nitrogen, other nutrients and even metals are an important new field for NIR.25

Fred checks his watch, but he doesn’t really need to—the cows let him know it is time for milking! Jack lends a hand, and together they relieve the cows of their precious white liquid which is the foundation of an important industry now closely monitored by NIR.26 Milk composition can now be tested on-line during milking, for fat and protein, and dairy products such as powdered milk, butter and cheese are routinely analysed on-line in dairy factories—not just for gross composition but also for sensory properties, texture, ripening and process control.27

As the afternoon wears on, Jack feels a little chilly, and dons his jacket—made, of course, from pure Australian wool! Estimation of wool quality was one of the first NIR applications ever attempted,28 but there have been many problems, especially with raw or greasy wool—again mostly due to sampling such a heterogeneous product. The New Zealanders have conducted a lot of research on scoured wool, and measurements of properties like residual grease and colour are now routine. Some studies have shown that NIR prediction of fibre diameter and yield in greasy wool is possible. Discrimination of components of wool-textile blends has also been found to be successful.29

It is now time for Jack Average to bid farewell to his brother after a pleasant day on the farm. He heads for home, but falls victim to temptation as he passes a winery, recalling that his cellar is rather depleted. He spends a good half-hour conducting his own personal experiment on sensory analysis. The wine and grape industry, although steeped in tradition, is increasingly embracing NIR as a tool to test the quality of both the grapes and the final product. Measurements of sugars, acidity, colour and pH of grapes are now frequently performed by NIR.30 Discrimination of various white and red wines has been conducted, as well as estimation of alcohol, glycerol and identification of wine yeast strains. Some studies have shown it is possible to use NIR to assess wine composition through the bottle.

Returning to the city, Jack calls his wife Jane, who has spent all day scrubbing floors, cooking and digging the garden. He proposes dinner in a nice restaurant, and even agrees to wait while she changes into her good clothes.31 Jack is a gentleman! They start off with crusty bread rolls, accompanied by extra virgin olive oil. Jane chooses Atlantic salmon on a bed of rice, and Jack has roast chicken, spuds and vegies. Jack has trouble choosing between an Australian Chardonnay and a New Zealand Sauvignon Blanc. They reach the obvious conclusion—both! The waiter (a part-time NIR technician) is disappointed to note that neither Jack nor Jane takes any interest in the fact that NIR is firmly established as a reliable method to assess the quality of olives and detect adulteration of olive oil.32 HE knows of the study that used NIR to measure pigmentation in live farmed salmon,33 and the important food safety development in which hyperspectral imaging was used to detect faecal contamination of poultry carcasses on the killing chain.34

Jane’s rice was probably tested by NIR; protein, amylose, gelatinisation temperature, cooking kinetics and discrimination between aromatic and non-aromatic varieties are some of the quality indicators of rice being estimated by NIR.35

And so... Jack and Jane drive home, Jack keeping an eye open for a dreaded “booze bus”. Unfortunately the traffic is awful, and they are seriously delayed. By this time Jack is tired and irritable after his big day, and the stress levels inside the car are gradually building up. The question is asked as to why some people complain about being tired after a pleasant day socialising, while others, who have been slaving at home, never complain. That does it—she can damn well drive! The result of all this is that Jack and Jane both have splitting headaches when they arrive home, and go straight to the medicine cupboard. Where would we be without pharmaceuticals? And where would the pharmaceutical industry be without NIR? This is one of the most important and expanding fields for NIR, but of necessity is subject to very strict quality control. NIR is ideal for this purpose, and is used to identify and monitor incoming raw materials,36 analyse for active ingredients,37 measure dissolution properties38 and mechanical performance of tablets—much of this on-line (process analytical technology, PAT). Another application is screening for fake and counterfeit drugs.

Jack is lucky he only has a headache. It could be worse. He may need to go to hospital one day—for a blood test, to be poked and prodded by an overworked and harassed doctor or even to have an operation. And what of NIR?39,40

Considerable research is going on in the medical field, and the potential in particular for non-invasive testing procedures and monitoring of patients during surgery41 is quite exciting. Investigations are continuing on non-invasive blood tests, such as glucose. This has been the “philosopher’s stone” for NIR for many years,42 but is not yet within reach. One day perhaps—who knows?

So much for a day in the life of Mr Jack Average. He really is a fairly boring sort of chap. If you asked him what NIR was, you would receive a blank stare. However, he is a citizen, a consumer and a voter. He has expectations about his quality of life which his grandfather would describe as unnecessary, wasteful and opulent. However, he has the luxury of better health (even if overweight), a much more varied diet and in many ways a far easier life than his grandfather had, although he reckons he has more stress, and he does live in a terrifying world. Via the internet, Jack has immediate access to information on everything from product quality to the weather, something his grandfather would never even have dreamed of. He is also more conscious of the effect of his activities on the environment, and should now realise that there is not an infinite supply of all the resources at his disposal. Whether overall he is more knowledgeable, community-minded and pleasant than his grandfather is, however, open to question.

One thing is certain. Although Jack Average is probably ignorant of it, the analytical technique of NIR spectroscopy has transformed the quality assessment of a huge array of natural and synthetic materials, products and processes; neither Jack nor even brother Fred realise that NIR is widely used in industry, petroleum43 and polymers44–46 being some recent examples. Whilst it is not perfect, and cannot measure everything, it is a vital tool in our modern armoury, and deserves to have a higher profile in the community—in industry, academia and government.

Maybe we should make more of an effort to educate our friend Jack—after all, I am told his second cousin, by marriage, is the brother-in-law of the Prime Minister.

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