Measure starch content in foods.

quas · #1 by **quas** » Jan 26, 2012 2:17 am

How do you measure starch contents in foods? Is there a meter for that?

quas · #2 by **quas** » Jan 30, 2012 6:43 am

Anyone knows?

Mazille · #3 by **Mazille** » Jan 30, 2012 6:52 am

Most likely in g per 100 g, I'd say.

Rumraket · #4 by **Rumraket** » Jan 30, 2012 9:24 am

Through some enzymatic analysis combined with Thin Layer Chromatography, for example.
There's a method:
http://www.akademiai.com/content/jh3w3j6403461113/fulltext.pdf

Summary
Starch is widely distributed in diverse plant organs as a reserve carbohydrate; it is also a major source of carbohydrates in human food. Because of its importance, different methods have been developed to measure the starch content of food and feed. Planar chromatography has been used to measure starch content of cereal products. The starch was hydrolyzed using α-amylase and amyloglucosidase and the resulting glucose was separated on silica gel 60 HPTLC plates and quantified at λ = 520 nm after derivatization. The glucose calibration plot was linear between 100 and 300 ng per spot with a coefficient of determination (r2) of 0.9959. The limits of detection (LOD) and quantification (LOQ) for starch as glucose
were 0.26 and 0.51 (g per 100 g), respectively. The mean concentrations of starch in wheat flour and in starch premix (an industrial product) were 74.56 ± 2.58% and 84.85 ± 1.96%, respectively. The proposed method was shown to be a precise, selective, and sensitive means of measuring starch in cereal products.

Rumraket · #5 by **Rumraket** » Jan 30, 2012 9:27 am

quas wrote:How do you measure starch contents in foods? Is there a meter for that?

There is no "meter" for something like this. You usually have to prepare your samples in a way that extracts the analytic(starch in this case) from the rest of the contents of the sample(fibre, fats, etc.), so you can determine how much there is.
Yes, the content is usually given in w/w %, e.g. g/100g.

quas · #6 by **quas** » Jan 31, 2012 3:26 pm

What about using a refractometer to measure Brix (sugar content)? Since starch is converted to sugar, then surely this could be an easier means of reliably measuring starch contents? Maybe not measuring the exact amount of starch, but just knowing which fruit contains more starch.

Rumraket · #7 by **Rumraket** » Jan 31, 2012 6:20 pm

quas wrote:What about using a refractometer to measure Brix (sugar content)? Since starch is converted to sugar, then surely this could be an easier means of reliably measuring starch contents? Maybe not measuring the exact amount of starch, but just knowing which fruit contains more starch.

I guess it depends on how precisely you want to determine it, and whether you want to know it's "truly" starch, as in amylose/Amylopectin and similar, or just any type of sucrose and other sugars.

Mazille · #8 by **Mazille** » Jan 31, 2012 7:11 pm

Oh, you meant a procedure to measure it. :oops:

Sorry.

quas · #9 by **quas** » Feb 05, 2012 3:47 pm

Rumraket wrote:I guess it depends on how precisely you want to determine it, and whether you want to know it's "truly" starch, as in amylose/Amylopectin and similar, or just any type of sucrose and other sugars.

Well, I just want to know whether my fruit is ripe enough to my liking.

DavidMcC · **#10** by **DavidMcC** » Feb 07, 2012 1:46 pm

Why not just take a test bite? Or is that too easy? :-)

quas · **#11** by **quas** » Feb 07, 2012 2:01 pm

It's too problematic. Can't get it the same all the time. If you could just take a bite to determine the consistency of food, then you wouldn't need all sorts of devices to measure ripeness of fruits, tenderness of meat, etc.

DavidMcC · **#12** by **DavidMcC** » Feb 07, 2012 3:49 pm

Oh, I take it you're a farmer. When you used the phrase "to MY liking" as opposed to PEOPLES' liking, I assumed that you were not a farmer, that you were not concerned about markets.

quas · **#13** by **quas** » Feb 08, 2012 2:36 am

Not a farmer, but close. A food producer.