Influence of conching temperature; Maltitol sugar alcohol in prebiotic milk chocolate containing inulin

European Food Research and Technology (Online First™), 2012

Changes in food consumption habits and the developments set forth in the area of health and nutrition also change consumer expectations and demands. Sugar-free foodstuffs and products that have prebiotic activity are among the primary features of such expectations and demands. In the present study, the effects of substituting fine sugar with isomalt and maltitol in milk chocolate

samples that contain inulin (9.0 %w/w), which is a substance with prebiotic activity, and the use of varying conching temperatures (CT) (50, 55 and 60C) in the sample preparation process on their physical (colour, hardness, water activity) and rheological properties were examined. Rheological data were obtained using the Herschel–Bulkley model which showed the best fitting for predicting rheology. It was determined that all properties included within the scope of the study are affected by the use of different bulk sweeteners or varying CT. While colour properties, such as brightness (L*), hue angle (h°), water activity (aw) and rate index properties varied in a narrow range, it was determined that the yield stress and viscosity properties, which are among the important quality parameters of chocolate and can have determining effects on sensory properties, manifest variations within a broad range, depending on the CT and the bulk sweeteners used. It was concluded that maltitol is a more suitable fine sugar substitute in milk chocolates containing inulin.  Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s00217-012-1873-x Authors Nevzat Konar, Ankara University Food Safety Institute, 06110 Diskapi, Ankara, Turkey   Journal European Food Research and Technology Online ISSN 1438-2385 Print 1438-2377

 

About Conching temperature when preparing chocolates

A conche is a surface scraping mixer and agitator that evenly distributes cocoa butter within chocolate, and may act as a ‘polisher’ of the particles.[1] It also promotes flavor development through frictional heat and release of volatiles and acids, and oxidation. There are numerous designs of conches, and food scientists are still studying precisely what happens during conching and why. The name arises from the shape of the vessels initially used, which resembled conch shells.

 

A conche is a surface scraping mixer and agitator that evenly distributes cocoa butter within chocolate, and may act as a ‘polisher’ of the particles.[1] It also promotes flavor development through frictional heat and release of volatiles and acids, and oxidation. There are numerous designs of conches, and food scientists are still studying precisely what happens during conching and why. The name arises from the shape of the vessels initially used, which resembled conch shells.

The conching process redistributes into the fat phase the substances from the dry cocoa that create flavor. Air flowing through the conche removes some unwanted acetic, propionic, and butyric acids from the chocolate and reduces moisture. A small amount of moisture greatly increases viscosity of the finished chocolate, so machinery is cleaned with cocoa butter instead of water.[4] Some of the substances produced in roasting of cocoa beans are oxidized in the conche, mellowing the flavor of the product.

The temperature of the conche is controlled and varies for different types of chocolate. Generally higher temperature leads to a shorter required processing time. Temperature varies from around 49 °C for milk chocolate to up to 82 °C for dark chocolate. The elevated temperature leads to a partially caramelized flavor, and in milk chocolate promotes the Maillard reaction.[1]

The chocolate passes through three phases during conching. In the dry phase, the material is in powdery form, and the mixing coats the particles with fat. Air movement through the conche removes some moisture and volatile substances, which may give an acidic note to the flavor. Moisture balance affects the flavor and texture of the finished product because, after the particles are coated with fat, moisture and volatile chemicals are less likely to escape.[3]

In the pasty phase, more of the particles are coated with the fats from the cocoa. The power required to turn the conche shafts increases at this step.

The final liquid phase allows minor adjustment to the viscosity of the finished product, which may be adjusted depending on the intended use of the chocolate. Fats and emulsifiers are added to adjust the viscosity, and thoroughly mixed.

While most conches are batch process machines, continuous flow conches separate the stages with weirs, over which the product travels through separate parts of the machine.[3] A continuous conche can reduce the conching time for milk chocolate to as little as four hours

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