Chocolate is characterised by its solid texture at relatively low temperature. However, it will easily melt as the temperature increase. This phenomenon contributes to the low level of chocolate quality in tropical countries. In order to cope with this problem, an innovation in producing thermostable chocolate is highly required. This work investigated the impact of fat content and palm sap sugar proportion on the heat stability of milk chocolate. Hardness of chocolate was used as a parameter to evaluate the chocolate stability against storage temperature. In this study, three levels of fat content, namely 30%, 32%, 34% and five palm sap sugar levels, namely 0%,25%,50%,75%,100% were used. The results showed that fat content, palm sap sugar proportion and their interaction significantly influenced the hardness of milk chocolate. Due to its moisture content, the hardness of chocolate increased as the proportion of palm sap sugar was increased. In contrast, at the same level of palm sap sugar proportion, the increase of fat content decreased the hardness of milk chocolate.

Tempering is one of the most important processes in chocolate making. Tempering is needed to ensure that chocolate has correct melting point, hardness, snap and gloss. After tempering, cocoa butter crystallises in polymorphic form beta V, resulting in chocolate with melting point in the range of 33-34°C. This work investigated the impact of crystal maturation duration and holding time of tempering process on hardness and appearance of dark chocolate. Five durations of crystal maturation, namely 1,3,5,and 7 days and five holding time namely 3,6,9,12,15 and minutes were used as variables. The results showed that hardness of chocolate had propensity to increase as the maturation duration was prolonged. Similar trend was also observed as the holding time increased. With regard to the colour, the L*, a* and b* values tended to decrease as the duration of crystal maturation increased. The use oven method, thus, seemed to have potential for small-scale production of dark chocolate.

Flow properties of chocolate highly determine mouthfeel and consumer acceptance. Aside from these, they are also important factors in determining the incorporation of chocolate in food products. This work investigated the possibility of using viscometer to determine the flow properties of molten chocolate. The data obtained from viscometer was fitted to Casson Model. Afterwards, Casson yield value and Casson viscosity were then derived. To observe the homogeneity of molten chocolate, thixotropy value was also determined. In this study, molten chocolate was produced using a stone melanger as an alternative processing method. Four grinding durations, namely 4, 8, 12, and 16 hours, were used to produce 4 types of dark chocolate. The results showed that viscometer was able to determine the value of Casson Model parameters, eventhough the shear rate reached was only approximately 45 s−1. Using this approach, it can be observed that the Casson Yield Value and Casson Viscosity increased as the grinding durations were increased.

Solanum betaceum Cav. fruit is renowned for having antioxidant activity because it contains phenolic compounds. This study aimed to determine the effect of some condition factor namely solvent composition, maceration time, liquid-solid ratio, and the particle size of S. betaceum Cav fruit to the total phenolic content and antioxidant activity. The fruit was collected from Temanggung, Wonosobo, and Kopeng, Central Java, Indonesia. The research used single-factor experiments and simplex lattice design (SLD) as an optimization method.  Total phenolic content was determined using Folin Ciocalteau reagent, while antioxidant activity was determined using 2,2-diphenyl-1-picrilhidrazil (DPPH) radical scavenger activity. The solvent combination which gave the highest responses was ethanol: water (60:40 v/v) with phenolic content of 7.48% w/w EAG. Maceration for 8 hours will produce an extract with the highest total phenolic content (8.76% w/w EAG). The optimal solvent ratio was at 10:1 v/w with total phenolic content of 7.26 ± 0.20% w/w EAG. The optimum particle size was 600-850 μm with a total phenolic content of 6.07 ± 0.18% w/w EAG. Antioxidant activity with the DPPH free radical scavenger capture method from three regions did not show significant results.