Acrylamide in potatoes (and other starchy foods) and what to do about it

[opsec]

http://www.sciencedaily.com/releases/2008/02/080229142817.htm

ScienceDaily (Mar. 4, 2008) — Several animal tests have shown acrylamide to be a carcinogen, and a recent study conducted by the National Food Institute, Technical University of Denmark, has shown a positive association between acrylamide and breast cancer in humans

.

The addition of rosemary to dough prior to baking a portion of wheat buns at 225°C reduced the acrylamide content by up to 60 per cent. Even rosemary in small quantities – in one per cent of the dough – was enough to reduce the acrylamide content significantly.

Flavonoids are another type of antioxidant found, among other things, in vegetables, chocolate and tea. Tests also showed that the addition of the flavonoids epicatechin and epigallocatechin from green tea considerably reduced the acrylamide content.

http://www.sciencedaily.com/releases/2008/03/080306075222.htm

ScienceDaily (Mar. 9, 2008) — Good news for chips lovers everywhere -- new research in the journal Science of Food and Agriculture shows that pre-soaking potatoes in water before frying can reduce levels of acrylamide.

Acrylamide is a naturally occurring chemical that occurs when starch rich foods are cooked at high temperatures, such as frying, baking, grilling or roasting.

The study found that washing raw French fries, soaking them for 30 minutes and soaking them for 2 hours reduced the formation of acrylamide by up to 23%, 38% and 48% respectively but only if they were fried to a lighter colour.

[Atash Hagmahani]

Potato chips aren't good for you anyway, Bud. Eat those spuds boiled or baked. 

[opsec]

I don't eat any kind of a fried potato, be it chips, fries or anything in between.

[Tom Wagner]

Acrylamide in potatoes (and other starchy foods) and what to do about it

I don't know how many times I have to be dismayed with scare tactics that reduce the consumption of potatoes and makes a potato breeder out to be an evil, really evil person just because he likes and admires potatoes in all ways.  I understand that Acrylamide can be a danger but not in the way the press, newpapers and the internet portrays it. I don't know how many times I run into people who brag, "I don't eat potatoes...I don't eat potato chips.....potatoes are fattening.....etc."  People read the newspapers, books, and internet news and naturally think they are informed about potatoes among other things. 

Twain was right.
"If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed."
— Mark Twain

Acrylamide is akin to the Global Warming debauchery, and the "what to do about it" is to destroy fuel sources, and that is not a slip of the tongue either.  The Acrylamide debauchery makes people give up on good food, tasty food, and I include potato chips in that category and their what to do about it is to give up on potatoes since they know not what really to do about it.  Opsec offers the tea and rosemary solutions....that is fine, I like that.  But what I want to offer is a plant breeder's solution...and that solution is predicated on knowing the pros and cons of the argument.  I am prefacing my arguments with a bit of copy/paste which barely covers what I am leading up to.

http://www.foxnews.com/story/0,2933,51186,00.html
This 2002 article more or less debunked the scare of….. acrylamide

The researchers claim that a single potato chip may contain as much as one-millionth of a gram (a microgram) of acrylamide.
Assuming for the sake of argument that the lab animal tests are relevant to humans, the lowest dose in lab animals at which a slight increase in cancer incidence was reported is 500 micrograms per kilogram of rodent bodyweight per day, according to the EPA.
For the average 70 kilogram adult (about 154 lbs.), that would be an equivalent dose of acrylamide of 35,000 micrograms. To get an equivalent daily dose of acrylamide as the lab animals, someone of average bodyweight would have to eat 35,000 potato chips (about 62.5 pounds) per day for life.
Referring to the chart below for the amount of acrylamide in foods, in a single day, the child can eat 13 kg (29 lb) of French fried potatoes, the woman can drink 86 kg (~86 L, or 23 US gal) of prune juice, and the man can eat 29 kg (64 lb) of oven baked potatoes, and each of them will have ingested less than 50 percent of the NOAEL of acrylamide. http://en.wikipedia.org/wiki/Acrylamide#Safe_levels_of_acrylamide

Does the ALAR scare mean anything to you?  Those of you who don't eat potato chips...who are you kidding in all due respect?  I can eat 35 chips if I am a real glutton but I would have to eat 1,000 times that every day to reach the projected toxic level of Acrylamide....I think other features of eating 35,000 chips in a day might kick in first....salt overload, too full, gassing out people, enough oil to pollute the Gulf of Mexico, exceeding my caloric intake...oh, good grief!

The Scientist today (2005) reports how a German study claiming that levels of acrylamide in the body might not be so strongly affected by consumption of acrylamide-containing fried foods as earlier research implied has come under heavy criticism from the team’s peers. Quite ironically, the magazine describes the disagreements as “bitter”.

Teratogenicity
http://www.inchem.org/documents/pims/chemical/pim652.htm
             

Administration of acrylamide to pregnant rats has been
             shown to produce neurotoxic effects (tibial and optic nerve
             degeneration) in neonates at levels that are non-toxic to the
             dams (Dearfield et al., 1988).  The lowest observed effect
             occurred at doses of 20 mg/kg/day.
   
             Edwards (1976) dosed pregnant rats with cumulative doses up
             to 400 mg/kg between days 0 and 20 of gestation and found no
             evidence of developmental or neurological abnormality in
             weanling rats despite evidence of neuropathy in the dams.
   
             No human data are available.

http://www.hc-sc.gc.ca/fn-an/securit/chem-chim/food-aliment/acrylamide/major_pathway-voie_09_mar_05-eng.php

Establishing the principal pathway of formation of acrylamide in foods allowed investigation of the effect of some parameters for reducing concentrations of acrylamide in potato-based products (chips, fries, etc.) Preliminary results indicate that the overall reduction of acrylamide formation can be achieved by:
•   reducing the concentrations of reactants needed for acrylamide formation - notably reducing sugars;
•   increasing the concentrations of reactants (e.g. other amino acids) competing with asparagine in the Maillard reaction;
•   changing processing conditions (lower pH, lower temperature, shorter heating times), thus altering the rate of formation of acrylamide;
•   scavenging already-formed acrylamide by other chemical compounds (via addition to the double bond).
Dietary Sources
Asparagine is not an essential amino acid, which means that it can be synthesized from central metabolic pathway intermediates in humans and is not required in the diet. Asparagine is found in:
•   Animal sources: dairy, whey, beef, poultry, eggs, fish, lactalbumin, seafood
•   Plant sources: asparagus, potatoes, legumes, nuts, seeds, soy, whole grains
[edit] Biosynthesis
The precursor to asparagine is oxaloacetate

http://www.i-sis.org.uk/acrylamide.php

The glyphosate (ie Roundup) herbicides of Monsanto Corporation are of particular concern because the herbicide interacts with the polymer [2-4]. Experiments showed that heat and light contribute to the release of acrylamide from polyacrylamide, and glyphosate was found to influence the solubility of polyacrylamide, so care was advised in mixing the two.
The evidence seems compelling, therefore, that acrylamide is being released from polyacrylamide in the environment, one of the main sources of which is in glyphosate herbicide formulations. Cooking vegetables that had been exposed to the glyphosate herbicide used with herbicide-tolerant crops, or used during soil preparation for normal crops would result in the releasing more acrylamide. Worse yet, additives such as polyacrylamide are designated ‘trade secrets’ in North America and information on the contents of herbicide preparations are not available to the public.

http://ddr.nal.usda.gov/dspace/handle/10113/1810

The free amino acid asparagine and the reducing sugars glucose and fructose has been reported to serve as precursors for the heat-induced formation of potentially toxic acrylamide in a variety of plant-based food. To contribute to our knowledge about the levels of these precursors, we used ion-exchange chromatography to measure free asparagine and high-performance liquid chromatography (HPLC) to measure free glucose, fructose, and sucrose in 9 potato varieties sold at retail in Italy and in 22 varieties sold in the United States.

 Asparagine levels (in mmol/kg of fresh wt) ranged from 1.17 for the Agata potatoes to 57.65 Russet potatoes, a 49.3-fold variation from lowest to highest value.
The corresponding levels for fructose ranged from 1.73 (Fingerling Ozette) to 33.63 (Red), a 19.4-fold variation from the lowest to the highest value.

For glucose, the concentration ranged from 1.11 (Jelli) to 34.73 (Yukon Gold B) potatoes, a 31.3-fold variation from lowest to highest value.

The corresponding values for sucrose ranged from 1.16 (Fingerling Ozette) to 40.61 (Marabel) potatoes, a 35-fold variation.

The American potato varieties Kennebec, White, and Fingerling Ozette and the Italian potato varieties Agria, Merit, and Marabel had very low levels of both asparagine and reducing sugars.

The results may enable consumers, restaurants, and processors to select commercial potatoes with low levels of acrylamide precursors for baking or frying.

http://www.ethlife.ethz.ch/archive_articles/070920-acrylamid/index_EN
shows that even dried pears and prunes can have higher levels of acrylamide.

http://en.wikipedia.org/wiki/Acrylamide

In the case of potatoes, for instance, the storage temperature should not drop below 8 °C (46 °F). When the temperature is as low as 4 °C (39 °F) the fructose content rises sharply, so that the acrylamide formation during baking or deep-frying will be higher. [citation needed]
New varieties of potatoes that produce less or no acrylamide are being bred.

I am my own worst enemy....I don't have the time to make myself informed, much less make the argument to inform anyone else.  But try I must.

If you notice some of the links about potato breeding and storage, reducing sugars, the projection of lowering the acrylamide by lowering the precursors such as the asparagine, and sucrose, glucose etc., and the reconditioning of potatoes stored at cold temps, or not putting them down at low temps to begin with.

Notice that three of the potato varieties that we eat are high in the measurements that might lead to the accumulation of acrylamide.  Russets, reds, and Yukon Gold...oh, great...are culprits.  How about someone like me who uses Ozettes, Kennebecs, Agria, and some of the other "good" potatoes in breeding schemes.   The hope is to combine the right combination that yet does not exist to lower all levels of the culprit catalysis   How about my Skagit Valley Gold that cooks in less time than conventional potatoes...less cooking and lower temps means you just might be able to eat 350,000 potato chips a day without ill effects.

Like I said, I don't have the time, the energy, the wherewithal to fully address this topic.  Nevertheless, I think I may have some partial information that allows me to offer a few more what to do about its to the industry.

Sorry about my soap box, I should use whatever soap is left and wash out my mouth.. Tom Wagner

[opsec]

Acrylimide is not a threat then. Cool. I still don't eat fried potatoes just because that's unhealthy for other reasons, but it's nice to know there's one less thing out there that's going to kill me.

[Lady Lilya]

From Wikipedia:

Acrylamide levels appear to rise as food is heated for longer periods of time. Though researchers are still unsure of the precise mechanisms by which acrylamide forms in foods, many believe it is a byproduct of the Maillard reaction. In fried or baked goods, acrylamide may be produced by the reaction between asparagine and reducing sugars (fructose, glucose, etc.) or reactive carbonyls at temperatures above 120 °C (248 °F).[10][11]
A study by the U.S. Food and Drug Administration (FDA) proposed a mechanism that involves asparagine, which, when heated in the presence of glucose, forms acrylamide.
Based on current stage of knowledge, acrylamide is a natural byproduct that forms when certain carbohydrate-rich foods are fried, baked, or roasted at high temperatures above 120 °C. Acrylamide causes cancer in rats when administered orally in high dose experiments, increasing tumors in the nervous system, oral cavity, peritoneum, thyroid gland, mammary gland, uterus, and clitoris.[12] There is a margin of 900-fold between the dose that gave cancer to 10% of rats and human exposure to acrylamide in the diet.[13]

Sounds to me like it has always been in cooked starchy foods, and always will be in cooked starchy foods.  So, I am not going to worry about it much.  (I eat a low-carb diet and a low-grain diet.  If I have a carb, it would likely be either fruit, rice, or potato.)

Interesting that the green tea flavinoids reduce it.  I drink a lot of that. 

[Atash Hagmahani]

I didn't tell him not to eat potatoes--just suggested baking or boiling them. You know I am pro-potato. Surprisingly nutritious compared to how easy-to-grow and productive they are. As discussed the only thing they seem to really be lacking are essential fatty acids. Not all that much protein but what is there is good quality--just don't peel them, or carefully pull only the outermost layer off after they're cooked (the protein is concentrated in that yellowish layer right under the skin, that gets peeled off if you peel them--that's why Grampa told you to "eat the peels it's the best part").

Instead of being defensive, maybe we need to be proactive. Openly promote potatoes. Potato-recipe-of-the-month. How about "featured variety of the month", Tom? Complete with pictures of skin, raw flesh, and final cooked product. Cross-post both on the forum, and on your blog.

[Tom Wagner]

I have never been organized enough to be overly diet conscious.  Omnivorous to a fault, perhaps.  But in regards to my breeding efforts, I try to concentrate on the healthful aspects of my work more so than in practice of eating healthy.  Seems the jury is still out on so many issues of what truly constitutes the positive and negative, without being swayed by public opinion that may in fact be totally wrong.  I do believe Atash is right about featuring potato varieties that have merit and could be increased as a clone or from hybrids of related lines of beneficial traits.

I mentioned a few potato varieties that would be good to work with, Kennebec, Agria, Ozette, etc., that in combinations of crosses could result in low asparagine and low reducing sugars...and then crossed with Skagit Valley Gold types that require very little time to cook, in fact are good raw.  The combination of these varieties could be a win/win deal because of the flavors, nutrients, etc., leading to even better varieties for our health and enjoyment.

More on these terms:  Asparagine, Fructose, Glucose, and Sucrose in Potatoes

Abstract http://www.ncbi.nlm.nih.gov/pubmed/17687697

Progress in developing genetic and agronomic approaches for reducing the levels of the principal precursors of acrylamide, asparagine and sugars in crop plants is reviewed. The factors that affect asparagine and sugar accumulation, particularly in cereal seeds and potato tubers, are described. Asparagine levels appear to be the key parameter in determining acrylamide formation in processed wheat flour and agronomic strategies for reducing asparagine accumulation in wheat grain are reviewed. Sulphur availability has been shown to be particularly important, with sulphur deprivation causing a dramatic increase in grain asparagine levels and acrylamide risk. Nitrogen availability is also a factor, with increasing nitrogen availability causing grain asparagine levels and acrylamide risk to rise. In potato, attention has been focused on sugars, and there has been some success in reducing sugar accumulation in stored potatoes by genetic modification, with a resultant reduction in acrylamide formation. However, the wisdom or otherwise of this dogma is discussed. Other possible genetic targets for manipulation or development as genetic markers in breeding programmes are reviewed. Plant breeders and farmers are encouraged to exploit the varietal differences in acrylamide risk that have already been identified and to develop good agronomic practice to reduce the levels of acrylamide precursors in cereals and potato.

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T6R-5004R4N-C&_user=10&_coverDate=05%2F01%2F2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1378218963&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=d3f2a9ab51da00e5fd24c1dccfc35dca

In this manuscript a sub-set of clonal progeny from a specific tetraploid potato breeding population has been assessed for acrylamide forming potential in stored tubers processed into crisps. The clone with the lowest acrylamide content in crisps had both low reducing sugars and asparagine contents. Our data show that, in the segregating breeding population used, both asparagine and reducing sugars levels needed to be taken into account to explain most of the variation in acrylamide and that selection for low levels of both metabolites should be targeted for crop improvement.
Keywords: Acrylamide; Asparagine; Plant breeding; Potato; Maillard reaction; Reducing sugars

1982   http://www.springerlink.com/content/y3r67352330ltj55/

Abstract  Low sugar accumulation during low temperature holding is a most sought after characteristic in a potato cultivar utilized for processing. Although this property is largely inherited, the lack of a reliable biochemical test capable of screening large numbers of new breeding lines with low sugar accumulating ability has hampered present selection procedures of plant breeders.

http://www.genetics.org/cgi/content/abstract/162/3/1423

Diploid potato breeding work indicates …QTL analysis revealed that QTL for glucose, fructose, and sucrose content were located on all potato chromosomes. Most QTL for glucose content mapped to the same positions as QTL for fructose content. QTL explaining >10% of the variability for reducing sugars were located on linkage groups I, III, VII, VIII, IX, and XI. QTL consistent across populations and/or environments were identified. QTL were linked to genes encoding invertase, sucrose synthase 3, sucrose phosphate synthase, ADP-glucose pyrophosphorylase, sucrose transporter 1, and a putative sucrose sensor. The results suggest that allelic variants of enzymes operating in carbohydrate metabolic pathways contribute to the genetic variation in cold sweetening.
Potato (Solanum tuberosum L.) breeders are interested in developing chipping cultivars that can be stored at cold temperatures to reduce storage losses and increase profitability for potato producers. Commercial cultivars accumulate reducing sugars during cold storage, resulting in unacceptably dark chips when processed. In this study, we have identified diploid wild Solanum species accessions that are resistant to cold-induced sweetening at very low storage temperatures (2°C). Selected accessions were crossed as males to haploids (2n = 2x) of S. tuberosum to produce adapted hybrids, some of which produce acceptable chips following 3 mo of storage at 2°C. Reconditioning for 6 d at 20 to 22°C increased the number of clones with acceptable chip scores by threefold. The best wild species parents were S. raphanifolium 296126, 310998, and 210048. While parental chip scores help to predict offspring performance, progeny testing is important to identify the best cross combinations. The best hybrids have been introgressed into diploid and tetraploid breeding clones. These hybrids produce good tuber type and low levels of reducing sugars under extremely low storage temperatures.
Abbreviations: chc, Solanum chacoense • oka, Solanum okadae • QTL, quantitative trait locus • rap, Solanum raphanifolium • spl, Solanum sparsipilum • stn, Stenotonum Group

http://crop.scijournals.org/cgi/content/abstract/47/Supplement_3/S-106

Potatoes (Solanum tuberosum L.) and humans (Homo sapiens L.) are both outcrossing species. The phenotypic variation of both is controlled by environmental factors and by natural DNA polymorphisms between individuals. Therefore we adopt similar approaches as used in human population genetics, such as association mapping, to identify loci and their alleles that are causal for complex agronomic characters such as quantitative resistance to pathogens or tuber sugar content.

ABSTRACT
Cold sweetening, the accumulation of reducing sugars in potatoes stored at low temperatures, results in dark chips unacceptable to the consumer. Developing potato cultivars that can chip directly from cooler temperatures (i.e., 3 to 4 C) requires the identification and use of new germplasm with cold-chipping resistance. Individuals from 16 haploid x wild species hybrid families were grown at two sites and their harvested tubers stored at 3 C for 15 wk. Following storage, individuals were evaluated for cold-chipping ability by (1) direct chipping, and (2) reconditioning for 2 wk at 18 C prior to chipping. At both sites, approximately 1% of progeny had good chip color
(1990) reported that two clones with S. phureja in their background, ND860-2 and ND2221-6, accumulated low levels of reducing sugars following 4 C cold storage for 100 days. ND860-2 is a parent of NorValley, a chipping cultivar with cold-- sweetening resistance (Novy et al. 1998)

I have used ND860 for many years in my crossing program.  Fully one half of the progeny are cold tolerant in that they don't develop the sweetness that is a major culprit in the Acrylamide production.

Lady Claire an Agria cross …. Lady Claire is a specialist crisping variety, with medium dry matters and very low, stable reducing sugars, ideally suited to long tem storage for late crisp production. It will produce moderate to high yields of round uniform tubers with low outgrades,
I am working with a series of Agria crosses this Summer..will test them for sugars.

Newer releases such as....

Premier Russet
(A93157-6LS)
A87149-4 X
A88108-7
1.0
Average yield, maintains low levels of
reducing sugars even after extended
storage, Med to late maturity, dual
purpose usage, PVY resistant, high
specific gravity

I have TPS of the Premier Russet and the F-1 family group had good flavor to boot.  It would be nice to save the genes for low levels of reducing sugars.

http://pubs.acs.org/doi/abs/10.1021/jf0706631

A recently developed intragenic potato plant is silenced for the polyphenol oxidase, dikinase R1, and phosphorylase-L genes in a tuber-specific manner. French fries derived from these tubers lack discolorations, display an enhanced potato flavor, and produce greatly reduced amounts of the suspected carcinogen acrylamide. It is argued that intragenic modification is unlikely to trigger phenotypic, biochemical, or physiological variation that is new to the species. Similarly, the targeted traits are similar to those that breeders select for and often have a history of domestication and reduced fitness. For these reasons, an updated regulatory system is proposed whereby intragenic crops are considered as low risk and should be cleared for commercial release in a timely and cost-effective manner. By using modern techniques to modify the same genetic material that is used by breeders, intragenic approaches may be perceived as an acceptable extension of traditional methods in crop improvement.

As I learn about the opportunities here for further breeding work, I will feature outstanding clones for testing by the readership.
Tom Wagner

[opsec]

I didn't mean to leave the wrong impression. I am far from being anti-potato in heart, mind, and deed. It's good to find out that acrylimide is a non-issue. I'm going to celebrate with a double order of hashbrowns.