White Chocolate with Resistant Starch: Impact on Physical Properties, Dietary Fiber Content and Sensory Characteristics

Resistant starch (RS) is a part of insoluble dietary fiber, and it could be recognized as a functional food ingredient in some types of confectionery products that lack dietary fiber. Unlike dark and milk chocolate, white chocolate does not contain fat-free cocoa solids rich in dietary fiber. In the present study, 5%, 10%, and 15% of white chocolate were substituted with RS in order to improve the nutritional value of enriched white chocolate. The influence of RS on rheological, textural, and thermal properties of the chocolate fat phase was firstly investigated, and then further influence on physical properties, dietary fiber content, and sensory characteristics of enriched white chocolates were investigated. The obtained results showed that enriched chocolates had increased content of total dietary fiber and reduced total fats and protein content in accordance with the added amount of RS. At the same time, RS increased viscosity and reduced the hardness and volume mean diameter in enriched chocolates in accordance with the added amount. RS improved the nutritional composition of white chocolate by increasing the content of dietary fiber. At the same time, RS did not impair the color and sensory characteristics of enriched white chocolates.

Characterizing Maillard reaction kinetics and rheological changes in white chocolate over extended heating

Molten white chocolate held at high temperatures for extended periods of time undergoes thickening and nonenzymatic browning reactions. Lactose and milk proteins participate in Maillard browning, which occurs more rapidly at higher temperatures. Crystallization of amorphous lactose and high temperature contribute to rheological changes over heating. In the present study, five white chocolates of varied compositions were sampled over time at different temperatures. White chocolates containing amorphous lactose showed increases in complex viscosity, while chocolates with crystalline or no lactose showed no change in rheological properties. Maillard browning was measured through both colorimetry and spectrophotometric analysis of brown pigments. Both markers showed the greatest browning for Nonfat dry milk (NFDM)-containing systems. Chocolates containing no NFDM (milk protein isolate, MPI, or crystalline lactose) showed no change in absorbance after clarification, but some browning in colorimetry results, likely due to residual amorphous lactose in the MPI or increased mobility of lactose from crystals at high temperatures. The evolution of fluorescent intermediates was visualized using fluorescence spectroscopy, revealing that these intermediates were formed prior to colored end stage products and were consumed as the reaction approaches completion. An excess of lactose in the system meant reducing sugar declines were relatively small throughout. Kinetic models were created to determine the influence of chocolate composition and temperature on thickening as related to complex viscosity (first order) and browning via colorimetry and absorbance (pseudo-zero order). Both thickening rate and Maillard reaction rates were faster in chocolates with greater levels of amorphous lactose and when held at higher temperatures. PRACTICAL APPLICATION: So-called "golden chocolate" is white chocolate that has been held at warm temperatures for a period of time to undergo Maillard browning. However, thickening of the chocolate during heating can cause processing problems. In this study, viscosity changes are correlated with Maillard browning kinetics to help chocolate manufacturers find optimal conditions for creating new products.

Investigation of chocolate types on the content of selected metals and non-metals determined by ICP-OES analytical technique

Chocolate, one of the most popular sweets in the world, is consumed by people of all ages. Available data point to significant increases in consumption and production. However, successful determination of elements in chocolate is still difficult because of the characteristics of the matrix which contains a high content of organic compounds, like hydrogenated vegetable oil, vegetable fats, solids from malt extract, salts, emulsifiers, etc., causing problems with appropriate decomposition or digestion of sample. In this study, chocolate samples were prepared according to two procedures: water bath and microwave-assisted mineralisation. The use of Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) allowed us to determine the elemental composition of dark, milk, and white chocolate bars available on the Polish market as well as a cacao sample (100% cocoa powder). The elements assessed were Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, Ni, P, S, Sr, and Zn. The obtained results were used to compare the effectiveness of sample pre-treatment methods and to assess the correlation between the concentrations of specific elements and type of chocolate by the application of chemometric and statistical tools. The research showed that levels of analysed macro- and microelements are directly connected with the type of chocolate, characterised by the variable contents of cocoa paste and added milk. Data for all samples after mineralisation shown that among macroelements P was the most abundant, followed by Mg, Ca, Na, K, and S. The major essential element with the highest level was Fe, followed by Zn and Cu. In the group of toxic metals the highest content was obtained for Ba, then Al and Sr, but none exceeded permissible values prepared by health benefit organisations.

Physical, sensorial and bioactive characteristics of white chocolate with encapsulated green tea extract

BACKGROUND

Many studies have described cocoa polyphenols as being bioactive compounds with a potential positive effect on human health. Although dark chocolate is a most powerful source of antioxidants, their content is lower in milk chocolate; conversely, in white chocolate the fat-free cocoa solids are omitted. The aim of this study was to increase polyphenol content and antioxidant capacity of white chocolate by adding encapsulated green tea extract (GTE) in amounts of 60, 80 and 100 g kg^-1 .

RESULTS

GTE influenced the particle size parameters, increasing the volume weighted mean from 15.43 μm in white chocolate to 19.34 μm in chocolate with 100 g kg^-1 GTE. At the same time, the viscosity of enriched chocolate also increased owing to the addition of new solid particles. The surface color of enriched chocolates changed in accordance with the amount of encapsulate, where all enriched chocolates had a slightly lighter color after 12 months of storage. Total polyphenol content (mg gallic acid equivalents (GAE) kg^-1 ) increased from 0.41 in white chocolate to 2.73 in chocolate enriched with maximal GTE. This amount of GTE increased antioxidant capacity (mmol Trolox equivalents kg^-1 ) from 1.22 in white chocolate to 16.12. After 12 months of storage, degradation of polyphenols was found to be a maximum of 37.27%, while antioxidant capacity decreased up to 44.14%.

CONCLUSION

In addition to the impact on chocolate viscosity, GTE added value through the polyphenol content and sensorial profile of the new product with an unusual green tea flavor and a shelf life of at least 12 months. © 2019 Society of Chemical Industry.