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Unused Bread as Value-Adding Ingredient

11 August 20175 min reading

The use of bread rework in industrial bread production helps minimizing food waste. Tests in the Bühler Bakery Innovation Center have shown that adding rework bread to the recipe can have quite a positive effect on the end product.

- Dr. Markus SCHIRMER  Head of Bakery Innovation Center - Fırıncılık İnovasyon Merkezi Başkanı - Susanne STEGHOEFER Project Manager Nutrition- Beslenme Proje Müdürü  Bühler AG buhlerAccording to current studies, about a third of all food is lost between the field and the table. To ensure more efficient use of resources in the future, this so-called “food waste” must be reduced. Bakery technology can also make a contribution to this objective. One point of approach is the reuse of unused bread.

UP TO 10 PERCENT UNUSED BREAD In the German-language regions, the term “Restbrot” is baked bread which is sorted out immediately after production and not sold. This unused bread consists of rejected sliced bread, errors in production, and overproduction, for example. This portion can make up 3-10 percent of finished goods, which in the case of an average line production of 3-4 tons/hour can mean up to 8 tons of unused bread per day. This unused bread can be put back into the process as a valuable ingredient, however. German law states that it may be reused as up to 6 percent of the ingredients in products primarily made of wheat, and up to 20 percent in products primarily made of rye, both percentages being calculated on the basis of the fresh bread. The residue may not be visibly detectable.

DRY REWORK PROCESS Before being returned to the process, the unused bread is often pulped with water. The resulting slurry, however, is at significant risk of contamination and cannot be stored for long. As a result, the direct use of dried unused bread, also called “dry rework”, is an alternative. However, until now there have been no investigations of the effects of this alternative on product quality. As a result, baking experiments were carried out to examine the difference between slurry and dry rework as well as the effect of different dry rework ratios on wheat breads (type 550 wheat flour, TA 165, 2% salt, 1.3% dry yeast, each relative to 100% flour). The quantity of rework added was deducted from the quantity of flour, so the total solid portion remained constant. Water added to the slurry was deducted from the bulk water quantity. The investigation examined baking loss, specific bread volume (AACCI 10-16.01), maximum hardness (AACCI 74-09.01), and sensory characteristics.

HARDER AND MORE COMPACT There was no difference between unused bread (10% relative to 100% flour) in slurry or dry form on the parameters investigated. Due to the very fine grinding of the dried rework, even without prior pulping there was no detectable residue in the finished bread. As the portion of dry rework rose (5%, 10%, 15%, each relative to 100% flour), the specific bread volume dropped significantly and maximum hardness rose significantly. The reason for this is that the share of functional gluten was reduced and the rework particles - which are similar to pentosanes - could move into the spaces between gluten filaments. These effects reduced the formation of gluten structure and led to a more compact product.

5 PERCENT ADDITION IDEAL The effect is reinforced as the portion of rework increases. On the positive end, it turned out that at 5 percent dry rework (relative to 100% flour) after 2 hours storage, the baking loss was reduced by 4.4 percent in comparison with the standard. This experiment shows that 5 percent rework (relative to 100% flour) is the upper limit for use in wheat breads, since at higher proportions the negative effects on product quality become perceptible. It was also determined that doughs with rework were significantly drier and firmer. As a result, the bulk water volume for 5 percent dry rework (relative to 100% flour) was increased in the final step. It was demonstrated that the reduction in specific bread volume could be partly compensated and the increase in maximum hardness entirely compensated by increasing the water volume by 2 percentage units. The reduction in baking loss remained constant at about 5 percent.

NO LOSS OF QUALITY It was thus determined that the use of dry rework is possible without loss of quality, while simultaneously increasing dough yield by at least 2 percentage points. Baking loss was also reduced by about 5 percent. There is potential for a further increase in dough yield, so that at constant product quality the water content could be increased by up to 10 percent by the use of dry rework.

BÜHLER REWORK TECHNOLOGY Bühler offers a unique rework technology for the reuse of dry unused bread. The freshly produced rejected bread is shredded, dried, and ground into fine particles. The resulting dry rework can be stored separately, then added to the recipe with the other dry components. This process allows unused bread to be converted directly into a storable raw material with low hygienic risk. In the product, dry rework enhances water binding and permits an increase in the quantity of bulk water. In comparison with the standard process, the Bühler process can be used more flexibly, bears less risk of contamination, and permits more efficient use of unused bread.

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