Optimization and coffee production from apricot kernel in various forms (liquid, powder and instant)

In this study, the possibilities of producing liquid, powdered and soluble coffee from apricot kernels of the Hacıhaliloğlu variety were investigated, using both the whole kernel and the press cake obtained by cold pressing. The Response Surface Methodology (RSM) was used to determine the optimum roasting temperature and time for coffee production from whole apricot kernels and press cake. This method was used to produce coffees in powder and liquid form at two different temperatures. During the production process, the kernels and press cakes were roasted at 176(±4) °C and 165(±4) °C for 10 min and then ground with suitable grinders to obtain liquid and powdered coffee forms. Instant coffee was produced from powdered coffee and liquid coffee by freeze-drying and spray-drying methods. The following values were determined in the coffee samples: Moisture 0.76–3.30%, water activity 0.079–0.213, fat 3.53–53.32%, protein 25.41–53.55%, ash 2.61–9.70%, amygdalin 167.70–559.24 mg/kg, acrylamide 1.46–7.28 mg/kg and HMF 2.98–15.60 mg/kg. For the instant coffees, a bulk density was identified between 0.184–0.250 g/cm³, tapped bulk density 0.220–0.377 g/cm³, a Carr index 16.96–24.03 %, a Hausner ratio 1.20–1.32, a solubility ratio 45.15–63.15 % and a wettability within 5.33–84.67 s were determined. In addition, some minerals Ca, Mg, Na, K, Zn, Fe, Cu and Al were quantitatively determined in the instant coffee samples. When analysing the volatile compounds, a total of 105 and 99 volatile compounds were identified in the coffees produced from whole apricot kernels and in the coffees produced from press cake, respectively. The study found that the type of raw material, roasting temperature and manufacturing process had significant effects on the properties of the final product quality (P<0.05). As a result, the research results showed that powdered products are more advantageous than liquid forms in terms of packaging, storage and marketing, in addition to ease of use. With regard to the production of instant coffee, it was found that coffee from press cake obtained using the freeze-drying method has better and superior product quality.