Temperature control facilitates chocolate quality.The migration of oil from high-oil-content centers into chocolate coatings can change the quality of the chocolate. Such changes in quality may include a loss of texture in the chocolate and filling, and the onset of fat bloom on the chocolate's surface.
Historically, this oil migration has been thought to be primarily diffusion-driven. But recent testing doesn't indicate that the migration is being driven solely by differences in chemical potential. Some believe that capillary capillary (kăp`əlĕr'ē), microscopic blood vessel, smallest unit of the circulatory system. Capillaries form a network of tiny tubes throughout the body, connecting arterioles (smallest arteries) and venules (smallest veins). forces are an important mechanism. The relative importance of capillary forces and diffusion may depend on storage temperatures, since the underlying structure of the solid phase changes dramatically from 20 C to 30 C.
Scientists at the University of California The University of California has a combined student body of more than 191,000 students, over 1,340,000 living alumni, and a combined systemwide and campus endowment of just over $7.3 billion (8th largest in the United States). at Davis examined the effects of temperature on fat migration in a model chocolate-peanut butter system. Their work reinforces the importance of controlling temperature to maintain the quality of filled chocolates.
In experiments, the investigators used a model system that consisted of a 1.25-cm peanut butter filling layer over a 1.25-cm layer of chocolate. Researchers stored three samples at 20 C, 25 C and 30 C. They used magnetic resonance imaging magnetic resonance imaging (MRI), noninvasive diagnostic technique that uses nuclear magnetic resonance to produce cross-sectional images of organs and other internal body structures. to measure liquid oil signal as a function of position over six weeks.
The pattern of oil migration differed significantly as a function of temperature in the three sets of samples. At 20 C, oil migration in the chocolate phase was slight. The dominant migration involved peanut oil peanut oil
The oil pressed from peanuts, used for cooking, in soaps, and as a solvent for pharmaceutical preparations.
Noun 1. separating at the top of the filling layer. At 25 C, oil migration into the chocolate phase exhibited a qualitative profile primarily involving Fickian-based diffusion--the basic relationship used to describe the nonconvective mass flux of a solute solute /so·lute/ (sol´ut) the substance dissolved in solvent to form a solution.
n. in a porous medium A porous medium or a porous material is a solid (often called frame or matrix) permeated by an interconnected network of pores (voids) filled with a fluid (liquid or gas). Usually both the solid matrix and the pore network (also known as the pore space) are assumed to be . A gradual gradient gradient
In mathematics, a differential operator applied to a three-dimensional vector-valued function to yield a vector whose three components are the partial derivatives of the function with respect to its three variables. The symbol for gradient is ∇. of liquid oil formed from the peanut butter into the chocolate.
At 30 C, the gradient in the liquid oil from the peanut butter into the chocolate changed rapidly. The liquid oil fraction in the entire chocolate region increased. This overall increase and the lack of concentration gradient concentration gradient
The graduated difference in concentration of a solute per unit distance through a solution.
Noun 1. are not consistent with a Fickian-based diffusion mechanism.
Higher temperatures do not give better control over oil migration. When two oil-containing layers are next to each other, as in peanut butter cups, the peanut goes into the chocolate faster at 30 C than at 20 C. And generally, consumers agree that the quality is lower with hard peanut butter filling and softer chocolate.
Further information. Kathryn L. McCarthy, Department of Food Science and Technology, University of California, One Shields Ave., Davis, CA 95616; phone: 530-752-1487; fax: 530-752-4759; email: firstname.lastname@example.org.