Marc Wandler, co-founder of Susgrainable and a pioneer in transforming beer waste into sustainable flour, shares his innovative journey. He discusses launching an upcycled barley flour product stemming from a student project, the challenges of sourcing during the COVID-19 pandemic, and the crucial role of consumer feedback in shaping his business. Marc dives into A/B testing methods, partnerships, and his vision for sustainability, all while navigating the unpredictable landscape of food entrepreneurship.