Giving New Life to Rusk and Crouton Side Streams

REBREAD'S COLLABORATION WITH BAKERY PRODUCERS

At Rebread, we carry out innovative R&D projects with producers looking for sustainable ways to repurpose production surpluses and side streams.We run an innovation process for producers that reuses raw materials and transforms them into new market-ready products.

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RUSK AND CROUTONS – UPCYCLING POTENTIAL

In 2024, in cooperation with one of the largest Polish bakery manufacturers, Rebread explored the reuse potential of side streams from rusk and crouton production. These by-products often contain additives that are challenging for fermentation processes. Our aim was to verify whether double baked waste could serve as a valuable raw material in fermentation and create new product categories. The project contributes to a broader vision of bakery production aligned with circular economy principles.

RUSK AND CROUTONS AS A BASE FOR FOOD & BEVERAGES

All tests on surplus rusk and croutons were conducted at Rebread’s R&D laboratory in Kraków, Poland. We focused on two fermentation technologies:

1. Solid-state fermentation – new bakery ingredient (CrumbsUp)

• Input material:
  Rusk and croutons with potentially problematic fermentation additives such as oil and pepper.
  
• Technological process:
  Solid-state fermentation using selected filamentous fungi strains.
• Yield:
  100 kg of double baked products generated ~70 kg of CrumbsUp ingredient.
  
• Result:
  A light-colored, mildly sweet, cheese-noted powder ideal for reuse in bakery mixes or bakery snacks.

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2. Liquid Fermentation – New Probiotic Drink

• Input material:
  Surplus rusks.
  
• Technological process:
  Lactic acid fermentation.‍
• Yield:
  More than 1,000 litres of beverage can be obtained from 100 kg of side streams from the production of rusks.‍
• Output:
  A low-calorie, plant-based drink with a creamy color and pleasant, slightly tangy flavor enhanced with natural juices. Application as a base for a functional, lactose-free alternative to traditional fermented beverages, fitting into the growing need for healthy and sugar-free plant-based drinks.

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Tests at Rebread confirmed that the re-use of rusks and croutons makes sense in terms of both performance and sensory qualities.

FEASIBILITY & FUTURE COOPERATION

The final test samples confirmed significant potential for integrating double baked production side streams into new product development. The fermentation results indicate the possibility of reintroducing rusk and crouton side streams as:

1. A functional snack ingredient, improving the macronutrient content of the final product along with the unique umami flavour. Applications include a 10% functional addition to rusk and snack mixes, or use as a umami flavour topping in savory snack products.
2. A probiotic beverage or beverage base – a low-calorie alternative to traditional fermented drinks, ideal for consumers looking for natural, healthy options such as kombucha or sugar-free plant-based beverages.
   
   

The producer we collaborated with expressed particular interest in our functional CrumbsUp ingredient and conducted additional tests in their own production facility. However, after performing profitability analysis and a market viability assessment, the company decided not to proceed with implementation. Nonetheless, they remain open to future cooperation on utiliising these materials in upcoming circular economy projects.

The project clearly demonstrated how double baked waste, which is usually difficult to reprocess, can be transformed into new value-added food products. By repurposing rusks and croutons, we create added value in the food sector through product innovation, upcycling, and sustainable food production.
It serves as a practical example of applying circular economy principles and responsible consumption.
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Current status: Completion of lab-scale formulation tests and pre-commercial testing in relevant environment conditions.