Nutrition label on pork rinds, protein content

[duffer]

I’ve noticed on a few brands of pork rinds and cracklins protein per serving up to 9 grams. But next to that a disclaimer that it’s not a significant source or protein. Don’t see that after the 7g listed for peanut butter. What’s going on?

[kenobi_65]

This blog post, which asks that very question, links to the Wikipedia article on pork rinds, which notes:

However, pork rinds are considered an incomplete source of protein because they contain very low amounts of some essential amino acids, including methionine, tryptophan, and histidine.

So, not all proteins are apparently not created equal.

[Ambivalid]

It’s because it’s an incomplete protein (lacks one or more essential amino acids).

ETA: ninja’ed

[Ruken]

tl;dr – what they said.

If you want more details:
21 CFR § 101.9 (c)(7)
I cut out the parts about food for children and infants.

When the protein in foods represented or purported to be for adults and children 4 or more years of age has a protein quality value that is a protein digestibility-corrected amino acid score of less than 20 expressed as a percent, […] either of the following shall be placed adjacent to the declaration of protein content by weight: The statement “not a significant source of protein,” or a listing aligned under the column headed “Percent Daily Value” of the corrected amount of protein per serving, as determined in paragraph (c)(7)(ii) of this section, calculated as a percentage of the Daily Reference Value (DRV) or Reference Daily Intake (RDI), as appropriate, for protein and expressed as a Percent of Daily Value.

[…]

The protein digestibility-corrected amino acid score shall be determined by methods given in sections 5.4.1, 7.2.1, and 8.00 in “Report of the Joint FAO/WHO Expert Consultation on Protein Quality Evaluation[.]”

That report is here: https://apps.who.int/iris/handle/10665/38133

Amino acid score: Amino acid ratios (mg of an essential amino acid in 1.0 g of test protein/mg of the same amino acid in 1.0 g of reference pattern for 9 essential amino acids plus tyrosine and cystine should be calculated by using the 1985 F AO/WHO/UNU (4) suggested pattern of amino acid requirements for preschool children (2-5 years). This reference pattern, shown in Table 7, contains (mg/g protein): His, 19; Ileu, 28; Leu 66; Lys, 58; Met + Cys, 25; Phe + Tyr, 63; Thr, 34; Trp, 11; and Val35. The lowest amino acid ratio is termed amino acid score. For example, a pinto bean sample contained 30.0, 42.5, 80.4, 69.0, 21.1,90.5,43.7, 8.8, and 50.1 mg/g protein of His, He, Leu, Lys, Met + Cys, Phe + Thy, Thr, Trp, and Val, respectively. The respective amino acid (His, Ile, Leu, Lys, Met + Cys, Phe + Tyr, Thr, Trp and Val) ratios for the bean sample would be 1.58, 1.52, 1.22, 1.19,0.84, 1.44, 1.28,0.80, and 1.43. This would then result in an uncorrected amino acid score of 0.80 with tryptophan as the first limiting amino acid.

d. Protein digestibility: True protein digestibility should be determined using the rat balance method as standardized by McDonough et al. (2) or Eggum (121). Data on fat and total dietary fibre in the test food should be used in adjusting the formulation of test and nitrogen-free (or low nitrogen) diets. They should be equal in levels of total fat and (where possible) fibre. Cellulose should be added to the diet only when the total dietary fibre content of the test food is less than 5%. The diets should also contain approximately equal amounts of moisture and lactose (in testing high lactose foods such as milk powder).

e. Protein digestibility-corrected amino acid score of a test food should then be calculated by multiplying the lowest amino acid ratio x true protein digestibility. In this report, the score is expressed as a decimal, but it may be expressed in percentage terms. In the case of the pinto bean sample having the lowest amino acid ratio of 0.80 and a true protein digestibility of73% [(as shown by McDonough et al (2)], the protein digestibility-corrected score would be 0.80 x 0.73 = 0.58 or 58%. Protein digestibility-corrected amino acid scores above 1.00 would be considered as 1.00 or 100%.

Anyone know if they actually go through this entire process with rats?

[Chronos]

But peanut butter is an incomplete protein, too. Is it still listed as a good source because it’s usually eaten with bread or other grain products, which complete it?

[Ruken]

Complete in that the lowest ratio of an essential AA vs the reference case times digestibility is above some threshold.

[Squink]

IIRC, pork rind amino acids, which make up protein, are mostly glycine, AKA aminoacetic acid, and hydroxyproline. Neither is essential, or very important.
Glycine os just dull, and hydroxyproline gets produced in collagen via post-translational hydroxylation of plain old proline. The hydroxyproline you eat is not going anywhere special.

[TruCelt]

I always thought there was a rule regarding the ratio of overall calories per gram of available protein in a processed food, which pork rinds would almost certainly fail. But I don’t see it in the regulation Ruken cited. Huh - ignorance fought.

[Jackmannii]

Very useful information provided here, thanks.

But I still believe a complete day’s nutrition can be provided by a diet of pork rinds, Slim Jims and Red Bull.

[Ruken]

Silly me for not checking Wikipedia first: Protein Digestibility Corrected Amino Acid Score - Wikipedia

Per this paper, “The limiting amino acid in peanuts varies based on the study i.e. lysine, methionine or threonine[.] The PDCAAS for peanuts has been estimated to be about 0.70 out of 1 where as for whole wheat PDCASS is 0.46 (Table ​(Table33).”