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The Science of Taste

This article by David Owen in National Geographic is chock full of interesting tidbits on the science of taste and flavor.  

For example, why many kids hate broccoli?

The aversion to bitter foods is inborn too, she said, and it also has survival value: It helps us avoid ingesting toxins that plants evolved to keep from being eaten—including by us.

The idea that many of us were taught as kids - that there are taste buds on different parts of the tongue that signal different flavors - is flat wrong:

It’s true that in some people the receptors for particular tastes may be more concentrated in certain areas on the tongue, but all of them are found all over, and a Q-tip dipped in lemon juice will seem sour no matter where you dab it. (The receptors sit on the surface of taste cells, which are bundled together in taste buds.)

and

Although the tongue map doesn’t exist, there may be a taste map in the brain . . .

That is, taste is about more than what hits our tongue.  

Taste receptors alone don’t produce tastes; they have to be connected to taste centers in the brain. In recent decades scientists have discovered receptors identical to some of those on the tongue in other parts of the body, including the pancreas, intestines, lungs, and testes. We don’t “taste” anything with them, but if, for example, we inhale certain undesirable substances, the bitter receptors in our lungs send a signal to our brains, and we cough.

Interestingly, most chefs are taught very little about the science of taste and flavor.

Stuckey teaches a course at the San Francisco Cooking School called “The Fundamentals of Taste.” “Most culinary schools don’t teach students how to taste before they start to cook,” she said. “They jump right in with, like, knife skills. But how can you possibly start an education around food without the building blocks of flavor?” She and her students do an exercise in which they make barbecue sauce. Most of the ingredients she provides are ones you would guess: tomato sauce, tomato paste, sugar, honey, liquid smoke, paprika. But there’s also a tray of ingredients whose predominant taste is bitter: coffee, cocoa, tea, bitters. “It’s not really intuitive, because you don’t think of barbecue sauce as bitter, but if you taste it before and after you add a bitter ingredient, you realize that bitter changes the whole gestalt

All these complex interactions make it tough when we decide to vilify an ingredient - say sugar or fat - because ingredients have complex interactions in term of smell, taste, mouth feel, etc.  In fact,, we can trick our brain into thinking something is sweeter than it actual is:

Bartoshuk told me that increasing the concentration of sweetness-enhancing volatiles in certain foods may make it possible to reduce their sugar content without making them taste less sweet. But she worries about unintended consequences. “As soon as we can produce a sweet experience that has no calories, isn’t toxic, and has no nasty characteristics—what will that mean for the brain?”

The whole thing is interesting.  

 

(HT Bailey Norwood)

Impacts of Agricultural Research and Extension

About a month ago, I posted on some new research suggesting decline rates of productivity growth in agriculture.  Last week at a conference in Amsterdam, I ran into Wally Huffman from Iowa State University, and knowing he's done work in this area, I asked him if he had any thoughts on the issue.  As it turns out, along with Yu Jin he has a new paper forthcoming in the journal Agricultural Economics on agricultural productivity and the impacts of state and federal spending on agricultural research and extension.  

Jin and Huffman also find evidence of a slowdown in productivity growth, writing: 

We find a strong impact of trended factors on state agricultural productivity of 1.1 percent per year. The most likely reason is continued strong growth in private agricultural R&D investments. The size and strength of this trend makes it unlikely for average annual TFP growth for the U.S. as a whole to become negative in the near future. However, for two-thirds of the states, the forecast of the mean ln(TFP) over 2004-2010 is less than trend. The primary reason is under-investment in public agricultural research and extension in the past. For public agricultural research where the lags are long, it will be impossible for these states to exceed the trend rate of growth for TFP in the near future.

They also find large returns to spending on agricultural research, and even larger returns to spending on extension.  They find the following:

For public agricultural research with a productivity focus the estimated real [internal rate of return] is 67%, and for narrowly defined agricultural and natural resource extension is over 100%. Stated another way, these public investment project could pay a very high interest rate (66% for agricultural research and 100% for extension) and still have a positive net present value. Hence, these [internal rate of return] estimates are quite large relative to alternative public investments in programs of education and health. In addition, there is no evidence of a low returns to public agricultural extension in the U.S., or that public funds should be shifted from public agricultural extension to agricultural research. In fact, if any shifting were to be recommended, it would be to shift some funds from public agricultural research to extension.

The paper includes a couple really interesting graphs on research spending and extension employment over time.  First, they show that for four major agricultural states, real spending on agricultural research peaked in the mid 1990s. 

And, while extension staff has declined in some states, it hasn't in others.  

Why we eat better today

Megan McArdle has an excellent post at Bloomberg review that she titled The Economics Behind Grandma's Tuna Casseroles.

McArdle sets out to explain why we eat differently (and in many ways better) than our grandparents.  Here's my favorite passage:

You have a refrigerator full of good-looking fresh ingredients, and a cabinet overflowing with spices, not because you’re a better person with a more refined palate; you have those things because you live in 2015, when they are cheaply and ubiquitously available. Your average housewife in 1950 did not have the food budget to have 40 spices in her cabinets, or fresh green beans in the crisper drawer all winter.

She also notes that food preference were probably similar in the 1950s as compared to today, it's just that our grandparents couldn't afford to eat the way we now do, and technological changes have made what were previously "fancy" foods available to the masses.  Take, Jello for instance:

The foods of today’s lower middle class are the foods of yesterday’s tycoons. Before the 1890s, gelatin was a food that only rich people could regularly have. It had to be laboriously made from irish moss, or calf’s foot jelly (a disgusting process), or primitive gelatin products that were hard to use. The invention of modern powdered gelatin made these things not merely easy, but also cheap. . . . Over time, the ubiquity of these foods made them déclassé. Just as rich people stopped installing wall-to-wall carpeting when it became a standard option in tract homes, they stopped eating so many jello molds and mayonnaise salads when they became the mainstay of every church potluck and school cafeteria. That’s why eating those items now has a strong class connotation.

There is a lot more at the link and the whole thing is worth reading.

Is the growth in agricultural productivity slowing?

Last week I gave a talk at the University of Nebraska, and Julian Alston from UC Davis was also there.  He presented some recent research with Matt Anderson and Phil Pardey about productivity growth in agriculture.  While I have seen some discussions about the possibility of a slowdown in productivity growth in developing countries, Alston's research suggest it is a phenomenon alive and well here at home.  This is important stuff.  Falling productivity growth has important implications for sustainability, food security, and research and development. They write

We detect sizable and significant slowdowns in the rate of productivity growth. Across the 48 contiguous states for which we have very detailed data for 1949– 2007, U.S. multifactor productivity (MFP) growth averaged just 1.18 percent per year during 1990–2007 compared with 2.02 percent per year for the period 1949–1990. MFP in 44 of the 48 states has been growing at a statistically slower rate since 1990. Using a longer-run national series, since 1990 productivity growth has slowed compared with its longer-run growth rate, which averaged 1.52 percent per year for the entire period, 1910–2007. More subtly, the historically rapid rates of MFP growth during the 1960s, 1970s and 1980s can be seen as an aberration relative to the long-run trend. A cubic time-trend model fits the data very well, with an inflection around 1962. We speculate that a wave of technological progress through the middle of the twentieth century—reflecting the progressive adoption of various mechanical innovations, improved crop varieties, synthetic fertilizers and other chemicals, each in a decades long process—contributed to a sustained surge of faster-than-normal productivity growth throughout the third quarter of the century. A particular feature of this process was to move people off farms, a one-time transformation of agriculture that was largely completed by 1980.

Here's a graph from their paper showing the change in proportional growth rate in yields (i.e., the log of yields) over time for 6 crops with the inflection point indicated for when growth rates began decelerating.