Is there science-based information on long-term white rice storage?

Question

I have some special white rice I picked up while traveling, and am conserving for the right dish because I can't buy it where I live. However, that got me wondering how long rice actually keeps. when stored reasonably, before quality starts to suffer.

After some searches, I am now even more unsure, because every source I look at seems to have a different answer:

• USA Rice: "Indefinitely"
• Minnetonka Orchards: 5 years, or 30 years with an oxygen absorber
• Utah State Univ. Extension: 10 years with an oxygen absorber, otherwise undefined
• Eat By Date: 4-5 years in jar, undefined "longer" when vacuum-sealed, supposedly based on the USU publication, except they have different numbers somehow?
• Numerous "prepper" sites, each of which offers slightly different numbers

The variance here suggests to me that the information available on the internet about long-term rice storage is largely based on hearsay, and not on scientific studies. The USU page has a bibilography that shows there have been several actual studies, but I cannot find any of the studies cited there in the science paper search engines I have access to (they may be only offline).

So, does anyone on SA have science-based information on how long one can store dry white rice at stable room temperature in normal consumer packaging before its quality starts to decline? And how rapid the decline is?

For bonus points:

• does vaccum-packing make a difference, without other oxygen-removal steps?
• does the type of white rice make a difference?

Footnote: I have found two questions on SA about rice storage, but neither one backs up their answers with science.

Answer 1

If you are more interested in the quality degradation rather than long-term storage safety, take a look at this paper on red rice.

It concludes that to maintain desirable quality, the best method is to store it vacuum-packed or at <15° C, but oxidation still begins to occur after 6 months in these conditions.

Important to note that brown and red rice degrade faster in these conditions compared to white rice due to the higher oil content, so these types of rice will begin to develop an off flavor.

https://onlinelibrary.wiley.com/doi/10.1002/jsfa.3976

Even though white rice will last longer before developing an off flavor, 2-acetylpyrroline, a compound that contributes greatly to the favourable character of fragrant rices, will begin to degrade regardless of storage conditions.

"It is thus concluded that, while it was found possible to inhibit the development of off-flavours to some extent, no way was found to assist the preservation of the desirable flavour compound, 2-acetylpyrroline."

https://onlinelibrary.wiley.com/doi/abs/10.1002/%28SICI%291097-0010%28199606%2971%3A2%3C218%3A%3AAID-JSFA570%3E3.0.CO%3B2-5

Answer 2

USDA states 2 years shelf stable for rice and pasta. https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/shelf-stable-food

Answer 3

Here are some additional resources I've found.

Of Interest

Storing White Rice

Additional Resources

Food Storage Guidelines for Consumers

A review on nutritional properties, shelf life, health aspects, and consumption of brown rice in comparison with white rice

Pantry Food Storage

Additional Thoughts

It should be noted that various factors can impact the declared shelf-life of any dry commodity, even for the same exact good between different food processing establishments. It comes down to the decision-making process of the facility QA team's hazard analysis and mitigation planning, the nature of the intended usage (NRTE vs RTE, etc), subsequent processing flow (e.g., CP's or CCP's in place, lethality or not, etc.), processing technology (e.g., high pressure pasteurization, IQF spiral freezing, etc.), local, regulatory, or retailer standards, and many other factors considered, covering the entirety of the supply chain. Then there's also the fact that the declared shelf-life of each product is determined by the senior management or QA; of course, there has to be evidence-based validation for the declared shelf-life, which is typically backed by a shelf-life study conducted by an accredited laboratory, and results may vary based upon many different factors (such as facility SSOP efficacy validation and responsiveness, or employee cGMP / hygiene practices, etc); however, even then, the establishment has some flexibility in what date they actually end up choosing to declare, based upon tolerance for risk, strategic factors, or other such influences. FYI, a commonly applied strategy is to declare a product shelf life that is one half of the actual shelf life as determined from the study. Additional considerations would be qualitative factors, which I won't be getting into; my point is that there is some subjectivity to contend with when speaking about declared shelf-life. The most objective way to determine an accurate, quantitative answer would be to take out representative sampling lots and have a lab conduct a shelf-life study while emulating the same storage conditions as the actual commodity. It would be up to you to define the critical parameters, but here is an example just for a very rough, general reference: