ABSTRACT
Objective was to enhance flavor precursors of unfermented cocoa beans by soaking beans in acetic acid and further heated by microwave. Acetic acid concentration, microwave power, and microwave exposure time were investigated and screened using a one-variable-at-a-time approach. Optimum condition for degree of hydrolysis (DH) was determined by Response Surface Methodology using Box-Behnken Design. Results showed that flavor precursors increased at a higher acetic acid concentration, microwave power, and microwave exposure time. Optimum condition was achieved at acetic acid concentration of 1.21 M, microwave power at 450 W, and microwave exposure time of 4 min. The microwave-assisted cocoa bean had a DH of 38.99% and a reducing sugar of 0.98%. Microwave-assisted heating increased amino acid content, especially hydrophobic amino acids as flavor precursors, and the main volatile compounds, especially aldehyde and pyrazine. Thus, microwave-assisted heating is a promising alternative to improve flavor precursors of unfermented cocoa beans.
ABSTRACT
Probiotic coffee is an alternative to processed coffee that is preferred and can improve the balance of intestinal microflora so that it has a positive impact on health. Cell viability of probiotics may decrease during storage. Factors that can affect viability during storage are storage temperature, packaging, oxygen, and water activity. This study is aimed at evaluating the viability, storage stability, and shelf life of the probiotic instant coffee Lactiplantibacillus plantarum subsp. plantarum Dad-13 in vacuum and nonvacuum aluminium foil packaging and different storage temperatures. This study used a complete randomised design with three replicates of treatments. They were packaged using 90 µm thick aluminium foil in a vacuum and nonvacuum and stored at 4°C and 30°C for 50 days and 37°C for 15 days. Based on the literature, a temperature of 4°C can maintain the viability of probiotics for more than one month, the temperature commonly used to store dry products is room temperature (30°C), so longer storage (50 days) is tried. Meanwhile, to accelerate the prediction of quality degradation, extreme temperatures were used based on the literature that the viability of probiotics decreased drastically after being stored at 37°C for 7 days, then tried for longer storage (15 days). The evaluation of product was carried by sensory testing by comparing commercial instant coffee. The product has been tested for cell viability, water activity, and shelf life. The result showed that the colour attribute was significantly different for all formulations. The bitterness of probiotic instant coffee differed significantly from other formulations. The commercial instant coffee was preferred by panellist in terms of colour and bitterness. The aroma, sweetness, and overall attributes of all formulations were not significantly different. The cell viability in vacuum was higher than nonvacuum treatment, and it was higher in 4°C. However, cell viability for all treatments and during storage was still above 107 log CFU/g. Water activity in probiotic instant coffee with vacuum packaging is lower than in nonvacuum and stored at 4°C lower than in other temperatures. However, all treatments were still below 0.60. The shelf life of products reaches two years when they are stored in vacuum packaging at 4°C while a temperature of 30°C reaches 3 months. So, the panellists accepted probiotic instant coffee, vacuum packaging, and low temperature could maintain viability, stability, and longer shelf life.
