Test if two foods are the same

I would suggest rather than testing it on other people who may not be able to tell the difference to have someone do a blind taste test on you. I would try the pasta without a sauce, or have a very simple sauce so you can really taste the pasta. Cooking it in the same pan at the same time sounds tricky, but if you can figure a way to keep them separated it would eliminate some variables.

If you want to test on a group of people it's best to keep it simple. An A-A and B-B test is never a bad idea, but you'd need to double your sample size in order to get decent results. If you have 8 or 10 guests split them in half and give half A first and the other half B first, that way you have 4 or 5 people trying each.

By the way, De Cecco pasta is available in the states and I'm pretty certain it's only made in Italy. I way prefer it to Barilla, if you can find it that might be the way to go.

This reminds me of a story I heard in statistics involving a claim by a woman that she could tell the difference between the difference between adding milk to tea vs adding tea to milk. A statistician overheard this boost and decided to design an experiment to determine whether her claim was accurate. If you use just two cups, one with milk added and one with tea added, well, even I have a 50% chance of choosing correctly just by picking one at random. It doesn't really tell us anything if she picks out the one with milk added.

It is possible to use statistics to estimate the probability that the observed results could be explained by someone just randomly choosing cups of tea. If that probability is low*, there is a statistically significant chance that there is something else to explain the results (i.e. that the tester can taster can tell the difference). Ideally, the scientist will design experiments before hand so that they know what significance level they can expect at the conclusion of the experiment. Using 2 cups of tea gives us a 50% probability that random chance explains the solution, so is not very meaningful. It turns out that an 8 cup experiment, 4 with milk added and 4 with tea added, makes it much more difficult to correctly identify the 4 cups with milk added if you just select them at random. Indeed, there's only a 1.4% that someone will correctly select the 4 cups. If the lady is successful, there is a high probability that she can actually discern the difference. If she got even one incorrect, however, that claim would not be statistically sound (there's an almost 1 in 4 chance of getting three of four cups correct if you just randomly select them--not terribly impressive).

Your pasta question is almost exactly the same as the question involving tea: can a person tell the difference between food A and food B. Only instead of whether tea is added to milk or milk is added to tea, you examine US pasta versus Italian pasta. The tea experiment required the drinker to correctly pick which ones had milk added. If you are only interested in whether your guests can tell the difference in the, but not necessarily whether they can correctly identify which is US and which is Italian, a similar experiment would only achieve a 2*1.4%=2.8% significance level. Still pretty good.

Of course, preparing 8 dishes per guest may be a bit of work. If you do 6 dishes, with 3 American and 3 Italian, you'd be right at 5% significance if a guest correctly chooses the pastas. Using 4 dishes would give you a 1/6 (16.7%) significance, and 3 dishes would just give a 1/3 (33.3%) significance. Up to you to determine how much confidence you want, and how much work you want to put into it ;).

Note that these numbers are for a single individual testing the dishes. Presuming you have a number of guests, the analysis gets more complicated, since you're adding in an additional variable (each individual is different). Generally, having more guests would help with you confidence that there is a difference in the pastas...if they are all able to pass whatever test you set up. If only a handful are, it's much harder to draw conclusions.

* The choice of the target probability that random chance can explain the observations (the null hypothesis) is arbitrary. A lower probability means you have more confidence in your observations, but requires more work. In many scientific fields, a level of 5% is considered "statistically significant", but there is push-back that a much smaller level should be used, as alluded to by @doneal24 in the comments.

The Barilla website says that different areas use different wheat at different times:

"Where is Barilla pasta made — in the United States or Italy?
Barilla Pasta that is sold in the United States is made in our plants in Ames, IA and Avon, NY, with a few exceptions. Barilla Tortellini and Barilla Oven Ready Lasagne are made in Italy. Our Barilla Italy products state "Product of Italy, Distributed by Barilla America, Inc." on the packaging. We also have product that is made in Canada. Barilla opened the Ames plant in 1998 and our Avon plant in 2007. The Barilla family was very concerned about maintaining Barilla's high quality standards in the new plant. Consequently, the machines used in our Ames and Avon plants are the same as used in our plant in Parma, Italy. The recipe and the wheat blend are the same as that used in Parma, Italy. Barilla purchases its wheat from around the world, ending up with the best wheat available.".

Wikipedia: Barilla:

"... The company markets pasta in the US as being Italian ("An Italian Favorite" marketing) in flavor, but most of the product in the United States is actually made in Iowa or New York and not Italy. The wheat used is mainly local.

Barilla Group has several production plants all over the world: in Italy, Greece, France, Germany, Norway, Russia, Sweden, Turkey, the United States (in Ames, Iowa and Avon, New York), and Mexico. The company also operates mills in Italy, Greece, Sweden, Turkey, and the US. While its central office is in Parma, it has corporate offices in several other countries as well, such as Austria, Belgium, France, Germany, Greece, the Netherlands, Poland, Russia, Slovenia, Sweden, Switzerland, Turkey, the US, Mexico, Brazil, Australia, and Japan. Barilla's Italian production facilities are located at Parma, Foggia, Marcianise, Castiglione delle Stiviere, Cremona, Melfi, Rubbiano, Novara, and Ascoli Piceno. Its plant in Greece (near Thiva) is the third largest in Europe. The plant where the pasta was made is noted on the packaging by a code letter, whereas products made in Italy are explicitly labeled as such. The wheat used to make the final product is purchased from around the world.

The recipe was changed in 2016, and is occasionally updated:

"The company continues to improve the nutritional profile of its products, replacing palm oil in its bakery portfolio and expanding the range of whole grain products.

The new Bio/Organic Pasta is launched on the European and US markets: 100% selected durum wheat from organic farms.".

Grain grown in different fields is transported via various routes to different markets by different train and trucking companies; all wheat isn't identical.

_{Click to zoom in on central USA}

Different countries have different regulations concerning the production of pasta, and there are different species of cultivated wheat. Durum wheat is usually used for pasta, it is ground for its wheat middlings and used to make semolina.

Barilla also changed its source of wheat due to concerns over glyphosate pesticides and contamination from Bayer Monsanto's RoundUp wheat.

That provides a few sources explaining why it tastes different depending on time and place.

I actually think vitamins can change the taste a little. If you try the Nequik cacao in the 1Kg bag vs the 600g plastic case you will taste a difference and the only real difference in the ingredients are vitamins. If it's true for cacao I think it should be true for pasta too