Signature Soy NON-GMO Soybeans for Natto 5 Lbs, Fresh Crop Small Size Soybean Review (2026)

Where these soybeans come from

Signature Soy grows identity-preserved, non-GMO soybean varieties on family farms in the Red River Valley of North Dakota and Minnesota, a region the company describes as having especially fertile soil for soybean production. According to the brand, its patented varieties have been chosen by some of the largest soy manufacturing companies for decades, which points to a consistent, food-grade growing operation rather than a generic commodity bean repackaged for home cooks. This particular listing is sized and marketed specifically for natto rather than for tofu or soymilk, which the brand sells as separate products.

Why bean size matters for natto

Natto is traditionally made with small soybeans rather than the larger varieties common in general cooking, because smaller beans ferment more evenly and give the dish its familiar texture once the fermentation coats each bean in the sticky compound natto is known for. Signature Soy markets this bag specifically as a small size soybean suited to natto, which aligns with what dedicated natto makers typically look for when sourcing beans, rather than substituting whatever soybeans happen to be available at a grocery store. Home cooks who have tried natto with mismatched, oversized beans often notice a firmer bite and less of the classic sticky strands, which is the practical reason bean size gets called out specifically in natto recipes.

What is not included

This is a beans-only listing, so no natto starter spores, or Bacillus subtilis culture, come with the order. Anyone without an existing starter needs to source one separately, whether that is a powdered spore product or a small amount of store-bought natto used as an inoculant. The bag also does not include any fermentation equipment, so a way to hold soaked, steamed beans at a warm temperature for roughly a day, such as a yogurt maker or proofing box, still needs to be arranged before a batch can be started.

Preparing the beans before fermenting

Making natto from raw soybeans starts with a long soak, commonly overnight, followed by steaming or pressure cooking until the beans are soft enough to mash between fingers, since undercooked beans will not ferment well and overcooked beans can turn mushy. This preparation step takes real time and planning ahead, unlike starters that arrive with pre-treated or partially processed beans, so buyers should expect a multi-stage process spread across at least two days from soaking to a finished, cooled batch of natto ready to eat or refrigerate. Planning the soak and steam around a weekend, so the long warm fermentation window falls when the kitchen can be left undisturbed, is a common approach among home natto makers.

How far 5 pounds goes

Based on figures reported by other growers in the natto soybean market, roughly one pound of dry soybeans yields a bit over two pounds of finished natto once soaked, steamed and fermented, which means a 5 pound bag can produce a substantial amount of natto across many batches. That makes this a practical size for anyone making natto regularly rather than testing it once, and the beans themselves store well dry in a cool, sealed container between fermenting sessions without needing refrigeration until they are soaked. A household eating natto a few times a month could reasonably stretch a 5 pound bag across several months of regular batches.

Frequently asked questions