Author Archives: madeleinet

The End to Expiration Dates

We have all had the experience of rummaging through the fridge, only to realize that the package of food has passed the expiration date. Or we may even neglect to discover this fact until after eating the food and our taste buds do the job our eyes did not!

There are countless perishable foods part of our daily consumption.
Source: Wikimedia Commons

This may all come to an end, as a colour-coded programmed tag is among the newest technology to detect how fresh perishable products are.  This tag is called a Time-Temperature Indicator (TTI), and a new version has recently been developed by researchers in China.  It is the size of a corn kernel and once placed on a jug of milk or a can of tomatoes, can change colour to indicate whether the product is fresh or already past the optimal edible duration.

Different colours correspond to different magnitudes of bacterial growth.
Source: American Chemical Society

This tag is gel-like and undergoes sharply contrasting colour changes to represent product quality due to temperature change as well as from microbial growth.  Over time, colour changes from red for “fresh”, when there are very few microbes, to green for “spoiled”, after temperature-dependent microbial growth has occurred.

This Time-Temperature Indicator is constructed with nanocrystals, which allow perishable products to be tracked and the deteriorative processes taking place to be mimicked in time with colour change.  The accuracy of its indicator colour to microbe activity has been tested in the study with E.coli growth, with successful results. The “programmable” part of the tag is the adjustment of its chemical properties to be tailored to the energy range that the food processes happens in.

The green colour of the tag shows that the contents of the bottle are spoiled.
Source: American Chemical Society

This video from the American Chemical Society (ACS) shows how the tag is used:

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The Time-Temperature Indicator is not a new invention, but low cost (less than one cent!) and increased sensitivity of nanocrystal technology in this version may lead to its availability to the general public in the near future.

By identifying when products are nearing or past the safe consumption period, TTIs can benefit society by reducing the amount of food waste if marketed for widespread use.  Food waste is a major issue in developed countries and the top reasons for throwing away food are all associated with food spoilage.  Sometimes shelf-life of perishable food is not accurate if there is improper handling, so this marker can minimize such risks to public health. On the flip-side, food may still be edible past the expiration date marked on the container, and the tag would be able to tell that.

Despite its small size, simple technological advances like this Time-Temperature Indicator can prove to have a large impact on our daily life, or at least help us eat our food in time.

Madeleine Tsoi


Is Obesity Caused By Pollutants Around Us?

If you are trying earnestly to maintain your weight, you may have the phrase “watch what you eat” in mind.  Junk food and sweets are out, but the question you forgot to ask is: should you be wary of other foods on your plate as well? The answer is yes.  

Studies have revealed that Persistent Organic Pollutants (POPs) play an indirect role in adding fat mass to the body.  People are affected by the environment because all our needs ultimately come from the surroundings and these very pollutants are able to enter your diet to alter the endocrine system, organ function, tissues, as well as fat cells.

Where Persistent Organic Pollutants (POPs) Come From

Predominantly used as pesticides, Persistent Organic Pollutants (POPs) are now under restricted usageThese chemicals were created for industrial processes and were also released as by-products. 

Smog filled with pollutants created from factories easily reach neighbouring crop fields.
Source: Gustavo Madico, Flickr

Once exposed to the environment, POPs travel far and wide, made possible by its resistance to most chemical and biological processes in normal degradation.  Naturally, animals consume available POPs, leading to its bioaccumulation  in tissues.  The problem is then amplified with biomagnification in food webs, and humans are, of course, at the top of the food chain.

This video by Sustainable Consumption and Production Regional Activity Centre summarizes the impact of POPs:

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The Link to Obesity

Since POPs accumulate in fatty tissues of animals, we consume them when our meal includes fatty fish, meat, and dairy products.

Fatty fish are victims of POP bioaccumulation.
Source: Ivan Walsh, Flickr

An increasing number of studies are finding a strong link between POPs and body weight.  POPs have been shown to affect key endocrine pathways in the human fatty tissue and there is a strong correlation between the expression of obesity marker genes (determinants of obesity) and POP concentrations.  In another study, a group of mice tested with a high-fat diet containing high POP levels gained more visceral body fat then the group of mice with a low-fat diet.   This indicated that metabolic processes were altered, leading to obesity and insulin resistance, which can progress to Type 2 Diabetes.  In fact, diabetes poses a possibly even more harmful health problem than obesity itself!

Possible Solutions

Despite the fact that POPs are highly regulated to limit its toxic effects, they can still be found in many environments because of the movement within food chains.  Does this mean you should lose all faith in the foods you eat? Hopefully not! As further research gives more evidence to support the causal role of POPs, awareness will increase and perhaps POPs will no longer be put in use.

It may be helpful to eat food grown with fewer pesticides, but a normal, balanced diet without excessive amounts of fatty fish and meat should be fine.

Post by Madeleine Tsoi

The Memory Game: Does Caffeine Help?

It is the night before that dreaded exam; the question surely revolving within your head is whether or not to chug down a cup of coffee.  If the goal is not to merely stay awake and finish reading those last few chapters but to keep your optimal level of memory up, then the following information is your key to success.

A variety of beverages contain caffeine, such as energy drinks.
Source: Daniel Jurena, Flickr

The Bad:

Caffeine has a half-life of approximately 6 hours which implies after a full 12 hour day, 25% of the original caffeine dose will still be present in your bloodstream.  Depending on dose, varying levels of sleep disruption or insomnia may follow.  In addition to not being able to sleep (which certainly will not aid your memory), the side of the coin people often overlook about caffeine is after its intake, as research has shown, the REM (Rapid Eye-Movement) phase and slow-wave deep sleep are affected.  REM sleep is believed to be the stage of the regular sleep cycle when memory is consolidated, thus it is critical that it remains undisturbed.

The Good:

Fortunately for coffee drinkers, there is new light shed on the beneficial effects of caffeine. Recently, a study conducted by undergraduate student Daniel Borota and a research team at John Hopkins University marked the first time direct results of caffeine stimulating the improvement of memory were recorded.  In the study, participants observed a series of simple everyday images including an office chair, a duck, and a saxophone.  To control for variances of individuals’ conditions, all participants viewed the images first, before half of the group was given a 200mg dose of caffeine while the other half was subject to a placebo.  The next day, the participants viewed another series of similar images and the group with caffeine intake the previous day was found to identify slight image differences with greater accuracy than the placebo group.  This differentiation is called pattern separation in neuroscience and leads to the conclusion that caffeine does indeed enhance memory consolidation in humans.

Dr. Michael Yassa from John Hopkins University further explains the study:

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There is a fine line between over-caffeinating yourself to cram for exams and taking a healthy dose of it to help with alertness.  This new research shows that perhaps, the recommended amount of caffeine to optimize memory may be 200mg- just about one strong cup of coffee.

Blog post by Madeleine Tsoi