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J C Andrews Address 2023: John D Brooks
Keep flaming the loop
This award is in memory of Dr John Clark "Jack" Andrews who proposed the establishment of the Chair in Food Technology at the University of New Zealand in the 1960s. It is largely through him that we are all gathered here today.
I never met Jack, but I had tea with him every morning, as his portrait hung in the staff common room in the Riddett Building. It’s a great honour to be joining the previous recipients of this award. Dr. Garth Wallace was the first recipient – he helped me when I joined the Food Technology Department at Massey in 1977. Professor Mary Earle, who became my mentor, was also an awardee. “Come on Brooks, get that PhD written.” Without her, I would never have completed the PhD write-up. My supervisor at Sydney University had abandoned five PhD students and I found it difficult to write up my work without supervision while writing lectures at Massey. When Wendy informed me of this award, she said the winner presents a keynote address on a topic of their choice at the NZIFST annual conference. Not an easy choice – Flying Gliders? Flying UAVs in Antarctica? Perhaps a lecture on food microbiology? Many of you will have already suffered my Food Micro lectures. Spoiler alert – you don’t get off scot-free. So, I’m going to pick out some aspects of my career – I have never worked in the food industry, but thinking back, it has always featured.
Continuous change
First I’d like to discuss briefly the changes that have occurred in the food industry over the last 70 years. Initially, it was very simple, most production was exported. Now our food has a much greater variety, comes from many sources and the storage, packaging, transportation and distribution have become much more complex. Who would have thought that oats grown in New Zealand would be exported and processed into oak milk overseas and then imported back here? Even food produced and sold here is considerably more complex, and central distribution hubs mean that supply chains are longer. Our diet has changed – 70 years ago, meat might have been eaten three times a day, particularly in rural areas, but now much less meat is consumed and some of us rely largely on plant-based foods.
Consumer expectations have also changed dramatically – they want a wide variety of foods, either fresh or processed and, with perfect reason, they want the food to be safe. This has led to increased legislation and regulation, such as the requirement for HACCPbased food safety plans. This is a worldwide phenomenon. In some cases, it leads to strange consequences. In Arkansas farmers’ markets, you can buy Non-TCS Foods, defined as “food that does not require time or temperature control for safety to limit pathogenic microorganism growth or toxin production and as defined in the rules of the Department of Health”. “Uncut fresh fruits and vegetables” are explicitly named as falling under the non-TCS foods category. The rules named “Ready-to-eat foods” as foods that are covered under the non-TCS foods. “Any ready–to-eat food that is prepared on-site or any food that is provided to the consumer in a non-prepackaged form can only be sold or served from an ADH-permitted and inspected facility. Any establishment preparing, selling, or serving any of these food items must fully comply with the Arkansas Department of Health’s Rules and Regulations.” Therefore, a tomato is a non-TCS food, however, a cut tomato may be considered a ready-to-eat food, so if the seller shows traditional southern generosity and cuts the tomato and offers a taste to the consumer, they are in contravention of the regulations. A similar situation arose here some years ago with the shelling of walnuts in the orchard or under a simple shelter, which was required to comply with the rules for a processing facility. The requirements of our trading partners have also become more stringent.
Lately, gene editing, ‘lab-grown meat’, and insect consumption have become hot topics. I’m going to leave it there as these ideas potentially open up new cans of worms if you will.
Finally, I think that we need to take more notice of our food consumers. The questions I receive from readers of my food safety blog and my own observations suggest that many people still don’t understand how to avoid food poisoning, and we don’t teach young people the basics of food safety.
Connections
It occurred to me that my career was a reflection of James Burke’s TV series “Connections”. He demonstrated how various discoveries, scientific achievements, and historical world events were built from one another successively in an interconnected but unpredictable way to bring about particular aspects of modern technology. Of course, the inventor of an accurate escapement mechanism for a clock probably didn’t realise that this would lead to more precise ship navigation. Some of the material I was taught as an undergraduate seemed to
have no relevance for me, but 50 years later, I find myself applying it. I don’t believe in fate, but it does seem that stuff just comes together in unexpected ways.
Student days
My journey started at Queen Elizabeth College, University of London, with a so-called Special Microbiology Degree. The Head of Department was S. John Pirt and there were 24 undergraduates. There were courses in Physical Optics, Surface Chemistry, Organic and Inorganic Chemistry, Maths, Calculus, and Electronic Circuit Theory. Somewhere, there was one course on Introductory Microbiology, and two years later, one on food microbiology, which didn’t particularly impress me.
Pirt had been a microbiologist at Porton Down, a science and defence technology campus in England, and had written a seminal text, Principles of Microbe and Cell Cultivation. He introduced us to a controlled environment culture apparatus of his own design and we conducted an experiment to measure a growth curve and set up a steady state.
We attended Intercol, a short series of lectures at various London colleges, on thermophiles and their enzymes, Again, this became relevant only much later when we studied thermophiles in the New Zealand dairy industry.
John Norris, author of “Methods in Microbiology” from Shell Sittingbourne, Kent came in to give lectures and run practical classes, introducing the concept of Single Cell Protein (SCP). (Remember, this was in the 1960s.) He encouraged me to spend a summer holiday at Sandoz in Switzerland, working on tissue culture.
Unexpectedly, the cells in the fermenter were alternately in carbon excess and then starved, over a period of 170 seconds.
Commercial SCP production
Immediately on graduation, encouraged by Pirt, (I don’t think he wanted me in his PhD student programme) I went to ICI to work on the SCP process. The initial substrate was methane, but that can be exciting, as it is explosive with oxygen, so methanol was substituted. ICI had ready access to methane and owned the low-pressure catalytic process to make methanol. Because of the huge energy requirements to stir a culture vessel capable of making 50,000 tonne/yr of SCP, it was decided to use an air-lift fermenter. Because of some concerns with the “pressure cycle fermenter”, I was tasked with modelling this device, so developed a modification of a lab fermenter. (The pressure in the culture fluid varied from 1 to 6.5 atm over the circulation period).
What we didn’t expect was that the cells would alternately be in carbon excess and then starved, over a period of 170 seconds. I found that with increasing cycle time, the cell yield dropped dramatically and carbon dioxide production increased proportionally. (See Fig. 1) I showed that this was caused by the energy-wasteful shuttling of glutamine and glutamate in an attempt to readjust their enzyme and key intermediate levels. The end result was that the process was modified by injection of methanol and air in the downcomer to prevent cyclic starvation.
A PhD in Sydney
After being told that I had reached my career maximum at age 24, I left ICI and went to Sydney to do a PhD, still working on C1 metabolism, with a grant from ICI. I studied the determinants of yield and attempted to find a predictive measure. This turned out to be the number of electrons available for oxidation in the substrate molecule. I wanted to find the number of sites of oxidative phosphorylation in the cells and grew them on methanol, formaldehyde and formic acid, the sequence of oxidation in the cell. Thus, I have the dubious honour of being the first person in the world successfully to grow bacteria in steady-state on formaldehyde. The basis for this came from a study of Pirt’s book – in steady-state, the residual concentration of substrate is practically zero. This study can’t be done in shake flask culture.
…and on to New Zealand
After the PhD, I couldn’t get a job in Australia – nobody wanted a fermentation engineer at that time, and the prospect of making paper bags or canning kangaroos for pet food didn’t appeal. I applied for and got the job of Lecturer in Food Microbiology at Massey University. I arrived in New Zealand on a Wednesday and gave my first lecture on the following Tuesday. I was terrified. I had 13 students in my class and they were only six years younger than I.
I stayed there for 30 years and perhaps my greatest achievement was to teach food microbiology to 940 undergraduates and some hundreds of Dairy Diploma students. I get great satisfaction from seeing those graduates in senior positions in the New Zealand and overseas food industries. Later, I spent a year teaching at Hong Kong University, where I had 360 undergraduates, and eventually was appointed Professor of Food Microbiology at AUT, where I developed and taught a course “Frontiers of Food Microbiology to 180 postgraduates.
At Massey, I was greatly influenced by a paper by A.N. Sharpe “Germ of a New Food Microbiology” in which he claimed that the true tragedy of agar is that it stimulated the development of a whole science around a unique type of analysis – The Plate Count. By its nature, it provides data so unique that they can be related to no other analytical data than those from other plate counts. Problems include whether the bacteria clumped, how vigorously the dilutions are prepared, whether they are viable but non-culturable or sublethally injured and whether they can grow on selective media. I studied many different automated analytical techniques that could speed up analysis and potentially provide more information on the microbiological safety and stability of foods, predominantly based on activity, but to this day, our microbiological specifications for food are still given in terms of plate counts. The number of specific bacterial cells in the food at point of production takes no account of handling in the supermarket or home. Will the numbers increase to hazardous levels or will they produce toxins? What we really need is to be able to show whether the food will spoil or become hazardous to the consumer and this requires dose-response data. Of course, we have no simple laboratory method of determining viruses in foods.
The biofilm project
Another major event occurred when Steve Flint came into my office in 1996 and asked if I knew anyone who could supervise a PhD on biofilms. I suggested that we could learn together He was at that time employed by the Dairy Research Institute and this gave us access to the industry. We joined with Dr. Phil Bremer and spent about 15 years studying thermophilic biofilms in dairy plants.
Sitting in a meeting of people from NZ Dairy Board, I heard that “Thermophilic bacilli do not form biofilms in milk evaporation and drying plant.” I didn’t believe this, as the residence time in the plant is too short for growth to occur in the flowing milk to the level seen in the finished powder. A calculation on the back of an airline ticket showed that thermophilic bacilli must form biofilms in the plant, growing and shedding both cells and spores into the flowing milk. Very quickly, we were able to show that vegetative cells and even spores can attach to 316 stainless steel in less than 60 seconds and become very difficult to remove fairly soon afterwards. Attachment is a multivariate process and depends on the suspending medium, the substrate's physical characteristics, whether it is clean or dirty, and the bacterial cells' surface. Lifschits-van der Waals forces, hydrogen bonds and electrostatic charge and the production of extracellular polymeric materials are all involved.
Steve and I were able to establish a biofilm research unit at Massey, with support from the “Plant Availability Project” of NZDB. We studied the attachment and growth of thermophiles and thermodurics and also the use of temperature cycling suggested by Geoff Knight in Australia. Our post-doctoral fellow, Shanthi Parkar studied cleaning methods specifically with respect to the materials of construction. We were ultimately able to work for a short time in a brand-new milk powder plant at Clandeboye and suggest minor modifications to the process.
Old microbiologists never stop working
Of course, all good things come to an end and I decided to retire. Initially, I panicked – “What am I going to do all day?” However, I have been a consultant to about 50 companies having problems with microbial contamination here and in Australia and I continue this work. Most recently, I went back to first principles (Thanks Pirt) to show that a shipment of frozen product to China must have been temperature-abused for 145 to 180 hours at one of two different temperatures prior to shipping. There is no software app that can do that. I am lucky to remain in contact with Steve Flint and am called upon to assess Food Technology student HACCP projects. Eventually, I began to wonder how I ever found time to go to work.
I guess old microbiologists never stop working, they just become more cultured.
Note that some illustrations have been removed for this article. The full text is in FNZVol23No4, Aug/Sept 2023