Effect of Sugar and Milk Powder Addition on the Mechanical Properties and Texture of Chocolate.

In order to investigate how the addition of two common ingredients in chocolate, sugar and milk powder, affects the mechanical properties of solid chocolate, uniaxial compression tests and wedge fracture tests were carried out using four ratios of chocolate as the experimental material. Mechanical properties such as Young's modulus and fracture toughness were directly correlated with textural properties such as hardness, elasticity, and brittleness. The results show that adding sugar increases Young's modulus and fracture toughness of chocolate, while milk powder is the opposite. In equal amounts of both, sugar played a more substantial role. In combination with the properties exhibited by chocolate in the above tests, data from creep tests were collected to improve the classical Bingham model and develop a new constitutive model for predicting the mechanical behaviour of solid chocolate with different ratios of added sugar and milk powder. The new four-component constitutive model allows for a more accurate fit to the creep test data and this work provides some suggestions for making different tasting chocolates by adjusting the addition of ingredients.

Effect of gelatin content and oral processing ability on vitamin C release in gummy jelly.

In order to investigate the factors affecting the release of vitamin C (VC) in gummy jelly during oral processing, four levels of gelatin (3%, 6%, 9% and 12%) were selected and a bionic chewing robot was employed in chewing experiments. Textural profile analysis showed the hardness of gummy jelly increased from 91.7 N to 198.8 N when the gelatin content was raised from 3 to 12%. Single factor chewing experiment showed that the release of VC was positively correlated with chewing frequency (Fchew) and chewing strain (STchew), while negatively correlated with gelatin content, chewing speed (SPchew) and volume of saliva (Vsaliva). Orthogonal chewing experiment showed that the priority of the factors affected the release of VC was following: STchew > Fchew > SPchew > Vsaliva. Multivariate linear regression analysis proposed a model to predict the amount of VC released and the goodness-of-fit of the model was 95.7%. The amount of VC released was the highest under the combination of Fchew 12 times, STchew 100%, Vsaliva 2 ml and SPchew 40 times/min. The optimal amount of gelatin addition was 6%. This study provided an effective reference for the formula design and chewing mode optimization of gummy jelly.

[Study on the synthesis of a new reagent 3-(4'-fluorophenyl)-5-(2'-arsenoxylphenylazo)-rhodanine and the fluoresence determination of bismuth(III)].

A new fluorescence reagent, 3-(4'-fluorophenyl)-5-(2'-arsenoxylphenylazo)-rhodanine, was synthesized. The structure of the reagent was clarified by elemental analysis and IR. At pH 5.4, the reagent can react with trace bismuth (III) to form a chelate which reduces the fluorescence intensity greatly. And when lambdaex/lambdaem = 305/407 nm, the fluorescence is intensive. There is a linear relationship between the decrease of fluorescence intensity and the concentration of bismuth (III) in the range of 0-0.025 microg x mL(-1). The detection limit is 1.2 x 10(-10) g x mL(-1). A new method of fluorescence spectrophotometric determination of bismuth (III) was developed.