FDA Warns RDM Express Over Sour Cabbage Listeria Controls

On September 11, 2026, FDA's Human Foods Program issued a warning letter to RDM Express Inc. of San Francisco, and FDA posted the letter on October 13, 2026. The agency determined that the firm's ready-to-eat Fermented Cabbage/Sour Cabbage products are adulterated under section 402(a)(4) of the Federal Food, Drug, and Cosmetic Act, and it cited misbranding on several labels. The letter does not state that Listeria monocytogenes was detected in the product, and it mentions no recall or illnesses.

Key takeaways

• FDA's September 11, 2026 letter (CMS #729223, posted October 13, 2026) cites serious CGMP and Preventive Controls violations under 21 CFR Part 117.
• The adulteration finding covers ready-to-eat Fermented Cabbage/Sour Cabbage products and rests on inspection findings and finished-product sample results.
• The letter does not say Listeria monocytogenes was found in the product.
• FDA said relying on finished-product pH alone is insufficient to control C. botulinum and Listeria, and cited pH 4.2 or below as a safety margin.
• Russian Style Kvas Drink, Sour Cabbage, and Half Sour Pickles labels drew misbranding findings under 21 CFR Part 101.

What happened: FDA's September 11, 2026 letter to RDM Express Inc.

FDA's Human Foods Program issued warning letter CMS #729223 to RDM Express Inc., naming CEO Boris Dinerman, at 2000 McKinnon Ave, Bldg 427, Unit #12, San Francisco, CA 94124. The letter is dated September 11, 2026. FDA posted it on its warning letters page on October 13, 2026.

The letter follows an inspection that ran from February 18 to March 10, 2026. FDA reported serious violations of the Current Good Manufacturing Practice and Preventive Controls rule, 21 CFR Part 117, which sets out food safety plan and control requirements for food facilities.

Why did FDA send RDM Express a warning letter?

FDA sent the letter because its inspection found serious violations of the CGMP and Preventive Controls rule under 21 CFR Part 117. Based on those inspection findings and analytical results for finished-product samples, FDA determined that the ready-to-eat Fermented Cabbage/Sour Cabbage products are adulterated under section 402(a)(4), which covers food prepared, packed or held under insanitary conditions. A Form FDA-483 was issued, and at the time of the letter FDA had not received a written response.

What changed: FDA's adulteration and misbranding findings, and what did not change

The letter lists several hazard-control gaps. The firm's food safety plan, dated April 30, 2025, did not identify recontamination with environmental pathogens such as Listeria monocytogenes. Product is packed into pails and containers under ambient conditions with no further lethal step. Sanitation logs did not identify the equipment or who cleaned it, and the firm had no environmental monitoring program. A hygiene checklist was marked non-compliant on dates between October 27, 2025 and February 23, 2026, with no corrective actions recorded.

The plan also did not address Cyclospora, norovirus and hepatitis A in the cranberries used as an ingredient. The letter says those cranberry hazards get no validated kill step, meaning no processing step has been validated to address them.

On labeling, FDA classed the problems as misbranding under 21 CFR Part 101. The findings cover the Russian Style Kvas Drink, the Sour Cabbage product, and Half Sour Pickles, and they are itemized in the labeling section below.

This is a single-firm enforcement action, not a new rule. The letter does not mention a recall.

Who is affected: sour cabbage, Russian Style Kvas Drink, and Half Sour Pickles

The adulteration finding targets the ready-to-eat Fermented Cabbage/Sour Cabbage products. The misbranding findings name the Russian Style Kvas Drink, the Sour Cabbage product, and Half Sour Pickles. The letter names only RDM Express Inc. It does not disclose retail brand names, retailers, or where the products are sold, so a shopper cannot match a package to the letter from the text alone.

What it means for shoppers: reading labels on ready-to-eat fermented products

A warning letter concerns the firm's processes and labels as FDA inspected them. It does not list specific retail packages, so the practical step is to read the label itself and compare it with the issues FDA raised:

• Product name: FDA suggested that 'Russian Style Kvas Drink' may need a more descriptive name conveying that it is a malt-based drink.
• Ingredient name: the kvas label uses an ingredient name that FDA said is not the common or usual name under 21 CFR 101.4(a)(1).
• Net quantity: the Sour Cabbage label showed net quantity by weight, but FDA said it must be a fluid measure.
• Volume format: Half Sour Pickles showed '32 FL OZ', which FDA said must read '32 fl oz (1 qt)'.
• Nutrition Facts: the kvas label lacked added sugars, vitamin D and potassium, as 21 CFR 101.9(c) requires.
• Russian-language text: the kvas label carried Russian text without repeating all required information in Russian, under 21 CFR 101.15(c)(2).

The letter also shows why process controls matter alongside acidity. Shoppers cannot see a plant's sanitation logs or pH records. The parts of a package that can be checked directly are the Nutrition Facts panel, the ingredient list, storage instructions, and net quantity. The label does not show a finished product's pH, so this article does not suggest that packaging alone can settle a safety question.

The background: the February to March 2026 inspection and the 2022 warning letter

The 2026 inspection ran from February 18 to March 10, 2026. The findings described in the letter draw on that inspection, on the firm's written plans and logs, and on an FDA sample collected February 25, 2026 (sample #1319005).

FDA also issued an earlier warning letter to RDM Express Inc. dated December 12, 2022 (CMS #643578). This article does not summarize that letter's findings, so readers who want the history should review FDA's December 12, 2022 letter to RDM Express Inc. directly.

For another recent FDA warning letter involving Listeria, see Dreyer's Ice Cream Plant Gets FDA Warning Letter Over Listeria.

What to watch next: the response to the Form FDA-483 and follow-up action

The letter asks RDM Express to notify FDA in writing within 15 working days of receiving it. It also states that failure to address the violations may result in seizure and/or injunction. The letter does not say whether the firm has responded since it was issued, and that response is not disclosed here.

Three items are worth tracking: whether the firm replies to the warning letter, whether FDA addresses the observations recorded on the Form FDA-483, and whether FDA posts further action on its warning letters page.

FDA's explanation of warning and close-out letters says a warning letter gives the company an opportunity to address FDA's concerns and respond within a set timeframe. Readers can review that process on FDA's page on warning and close-out letters.

Why pH alone did not satisfy FDA: Listeria, C. botulinum, and the 4.2 benchmark

The firm's plan relied on finished-product pH alone to control C. botulinum and Listeria. FDA said that approach is insufficient, because Listeria is acid-tolerant.

Can Listeria survive in fermented cabbage?

The letter says Listeria is acid-tolerant, which is why FDA did not accept finished-product pH alone as a control. The letter does not state that Listeria was found in the product, so the finding rests on the control gaps and the sample results rather than a reported positive test.

An FDA sample collected February 25, 2026 (sample #1319005) had a pH of 4.0 to 4.17 and a water activity of 0.98. The firm tested pH from the barrel after fermentation, not at packaging. The pH meter was calibrated only once a week, and no validation study was provided. The firm's pH critical limit is not disclosed in the letter, so this article cannot say what limit the firm set.

What pH kills Listeria in fermented foods?

The letter does not name a pH that kills Listeria. The only pH benchmark it states is 4.2 or below, which FDA described as a way to add a safety margin against C. botulinum.

Is RDM Express's fermented cabbage safe to eat? What the letter establishes

The letter does not establish that any specific package is unsafe. It does not report a Listeria detection, illnesses, or a recall. What it does establish is FDA's determination that the ready-to-eat Fermented Cabbage/Sour Cabbage products are adulterated under section 402(a)(4), based on the inspection and sample results described.

This distinction matters. An adulteration finding under section 402(a)(4) concerns how a product was prepared, packed or held, so it can rest on process failures such as missing environmental monitoring, incomplete sanitation records, and unaddressed ingredient hazards without a reported positive test.

What is a warning letter, and how does it differ from a recall?

A warning letter is FDA's written notice that it found violations and expects correction. Under this letter, RDM Express must respond within 15 working days, and failure to address the violations may result in seizure and/or injunction.

A recall is a company's removal or correction of a product already on the market. This letter mentions no recall and no illnesses. For a different situation, read Starfish Smoked Salmon Listeria Recall: Check Lot D080-148, which concerns a recall rather than an enforcement letter.

How to spot the labeling issues FDA cited on kvas and Half Sour Pickles

FDA cited the Russian Style Kvas Drink label under 21 CFR 101.4(a)(1) for an ingredient name that is not the common or usual name, under 101.15(c)(2) for Russian-language text that does not repeat all required information, and under 101.9(c) for missing Nutrition Facts content, including added sugars, vitamin D and potassium. One ingredient name on that label is redacted in the letter, so this article cannot say which ingredient it is.

A practical check is to compare each ingredient name with the common names you recognize, confirm that a Nutrition Facts panel is present, and check whether any Russian-language panel carries the same required details as the English panel. For Half Sour Pickles, the volume should read '32 fl oz (1 qt)' under FDA's description, and for Sour Cabbage, the net quantity should appear as a fluid measure.

Fermented vegetables and kvas carry ingredient lists worth reading. Scan the next jar or bottle you buy with the Aurascan app to see what each ingredient is.