Guest Demonstration: Carlo Di Cristo

Why It Matters

Understanding sourdough’s microbiology lets bakers control flavor, texture, and shelf life, turning a traditional craft into a predictable, scalable process.

Key Takeaways

• Sourdough fermentation relies on natural microbes in flour and water
• pH readings are non‑linear; taste is a better sourness gauge
• Liquid vs. stiff starters produce distinct crumb texture and flavor profiles
• Fermentation variables like water, salt, temperature control dough time
• Bacterial exopolysaccharides improve bread moisture retention and shelf life

Summary

University researcher Carlo Di Cristo took the stage to demystify sourdough, explaining how a simple mixture of flour and water becomes a living ecosystem of bacteria, yeasts and molds that drive bread fermentation.

He emphasized that the spontaneous acidification of the dough is not linear; pH drops rapidly at first and then slows, making pH meters unreliable. Instead, he urged bakers to trust their palate. He also contrasted liquid starters, which are 100 % hydration, with stiff starters (40‑50 % hydration), showing how water content reshapes microbial populations and yields noticeably different crumb structure and chew.

During the live tasting, three loaves—light durum, multigrain, and a middle‑brown loaf—illustrated the impact of starter type on flavor and texture. Di Cristo highlighted that bacteria produce exopolysaccharides that trap moisture, extending shelf life, and that the balance of lactic and acetic acids creates the characteristic sour aroma.

The talk underscores that a scientific grasp of fermentation variables—hydration, salt, temperature, and timing—allows bakers to fine‑tune product quality, reduce waste, and innovate with new textures, a competitive edge for both artisanal and industrial operations.

Original Description

Le Cordon Bleu is delighted to host a guest demonstration with Carlo Di Cristo. Carlo is a baker, biologist, and university researcher from Naples, specialising in fermentation science, sourdough technology, and advanced panettone processes.