Grindstone Bakery was founded in 1999 in a small "garage" in Santa Rosa, California, where we experimented with alternatives to modern wheat and created fermentation cultures for an authentic sourdough process. My father had been a partner at a flour mill. I grew up in Argentina among grain fields and all kinds of flours and breads. I wanted to be a chemist, so my father thought that the natural path for me was to be the mill’s chemist. But during my studies I was captivated by the world of science and decided that just testing flours was not enough of a life. So, I went on pursuing an elusive career in science. Today, I am extremely happy that I have found myself baking once again. Baking is a science that requires the precision and rigor, the experimental and inquisitive skills that are rooted in my scientific background. Baking is also an act of love that now provides meaning to my life.
~Mario Repetto, the Baker


Stone milling is the oldest, slowest, and best method of grinding whole grains. It is a gentle and cool process that preserves every good part of the grain. All the protein, oils, antioxidants and vitamins from the germ; all the sugars and starches from the endosperm, along with the tiny bits of bran rich in antioxidants and fiber are all there. Nothing is added and nothing is taken away. We slowly grind our whole grains using a small, natural, pink granite stone mill that never overheats the flour. We transform it into living dough within hours of being ground.

In today’s completely automated milling process, steel rollers crush the grain at remarkably high speeds, heating it to elevated temperatures and destroying vitamins and antioxidants in the berry. Sifters remove the germ and all bits of bran from the flour. Some of the separated parts can be later mixed back to produce a so-called whole wheat flourl; but the germ is never added back because, exposed to air and heat, it oxidizes and becomes rancid.

Whole grains are seeds coming from plants that, over millions of years, have developed the capacity to synthesize myriad phytochemicals that help them resist pathogens, parasites and predators, or attract beneficial organisms. We call these beneficial phytochemicals antioxidants. Our modern understanding on how they function in plants is helping us to discover the mechanisms by which whole grains benefit human health beyond basic nutrition. More than 8,000 phytochemicals have been identified, but a large number still remains unknown.

More and more convincing evidence suggests that the benefits of antioxidants in fruits, vegetables and whole grains may be even greater than is currently understood. Our body, it turns out, needs this synergistic effect – this teamwork – that is produced by eating a wide variety of plant foods.

Cells in humans and other organisms are constantly exposed to a variety of oxidizing agents, some of which are necessary for life. These agents may be present in air, food, and water, or they may be produced by metabolic activity within cells. Overproduction of oxidants can cause an imbalance, leading to oxidative stress, especially in chronic bacterial, viral, and parasitic infections. Oxidative stress can cause oxidative damage to large biomolecules, such as lipids, proteins and DNA.

To prevent or slow the oxidative stress induced by free radicals, sufficient amounts of antioxidants need to be consumed. The key factor is to maintain a balance between oxidants and antioxidants to sustain optimal physiological conditions. The lactic acid bacteria in our fermentation cultures are capable of unbinding these critical antioxidants from the bran and germ making them immediately bio-available for the protection of our cells.

In addition, lactic acid bacteria, being avid seekers of the amino acids needed for growing and multiplication, generate powerful external enzymes capable of breaking down complex proteins. This action has two positive effects: one that benefits our palate and the other our health.

Very much like in cheese-making, where the fermentation with lactic acid bacteria cultures breaks down complex milk proteins creating peptides (small protein fragments) with delicious flavors and aromas, our fermentation does the same with the proteins in the whole grain, generating flavors, a dense crumb, and a wonderfully satisfying chewiness. Because the complex proteins that form gluten are delightful targets for them, fermentation by lactic acid bacteria has been shown to substantially reduce the gluten content in bread. Ancient civilizations that ate naturally fermented whole grain bread did not suffer gluten intolerance issues.

All this may help explain why traditional cultures eating diets high in naturally fermented whole grains consistently have better health. Short-term clinical trials focused on fiber alone have yielded inconsistent results. So, the explanation for the health benefits of naturally fermented whole grains may arise from the teamwork of nutrients, protective antioxidants and lactic acid bacteria, not just their fiber.

Our fermentation cultures are the result of years of capturing and experimenting with different combinations of the wild lactic acid bacteria naturally present in the Sonoma Wine Country environment. We call them Sonoma Cultures, and each one has a particular ecosystem of several lactic acid bacteria strains, allowing us to create different breads with a relatively lower acid content than most sourdoughs, rich in flavor and color and resistant to spoilage without the use of preservatives.