## 2 Materials and Methods
### Production of Modified Starch Preparations  
An apple concentrate (80\({}^{\circ}\)Bx) was diluted to 20\({}^{\circ}\)Bx and fermented for 30 days with Saccharomyces byanus CH158 yeast. The resulting solution was cooked to remove ethanol and then concentrated to 50\({}^{\circ}\)Bx in an air-dry at a temperature of 35 \({}^{\circ}\)C. The pH value of the apple distillery wastewater concentrate was adjusted to pH 3.5 using 10 M NaOH. The concentrate of apple distillery wastewater was applied onto potato starch in the amount of 30 g distillery dry matter per 100 g starch dry matter. The sample was then mixed and conditioned at a temperature of 20 \({}^{\circ}\)C for 24 h and afterward air-dried to a moisture content of 16 g/100 g. The mixture was extruded in a Brabender 20 DN single-screw extruder at the following temperatures (in consecutive sequences): 60-70-80; 80-90-100; 100-110-120, or 120-130-140 \({}^{\circ}\)C. The extrusion process was performed with a nozzle 4 mm in diameter and a screw with a compression rate of 1:1. Feeder speed was 50 rpm and screw speed was 120 rpm. The obtained extrudates were roasted at temperatures of 80, 100, 120, or 140 \({}^{\circ}\)C for 3 h. Next, they were soaked in distilled water for 24 h and homogenized in a Thermomix multifunctional device (Vorvex). Then, ethyl alcohol was added in the amount ensuring final alcohol concentration at 65%. The sample was left to stand until a clear solution was obtained, which was then decanted from above the precipitate. Next, the starch was again poured with a 65% ethanol solution. The rinsing process was repeated 30 times. The purified preparations were air-dried at a temperature of 35 \({}^{\circ}\)C, ground in the Thermomix, and sieved through a screen with mesh size of 400 \(\upmu\)m. The preparations produced acc. to the analogous procedure but without apple distillery wastewater were rinsed only once and served as the control sample. Qualitative and Quantitative Analyses of Starch Esters with the High-Performance Liquid Chromatography (HPLC) Technique  
The chromatographic analysis of organic acids was carried out in refined and de-esterified preparations [12]. Roasted extrudates were prepared for determinations through refining, which allows assuming that all free acids were removed from the sample. Twenty grams of the preparation was transferred to a conical flask containing 300 mL of distilled water. The suspension was brought to the boiling point and stirred until the preparation dissolved. After cooling, 1 L of rectified ethanol was added to the flask to allow for starch precipitation. After 24 h, the clear solution was decanted from above the precipitate. The refining procedure was repeated two more times, and the resulting preparation was air dried at a temperature of 30 \({}^{\circ}\)C and ground. Next, it underwent base de-esterification. To this end, 2 g of the preparation (per dry matter basis) and 100 mL of 0.5 M NaOH were stirred at a temperature of 35 \({}^{\circ}\)C for 12 h. Then, 400 mL of rectified ethanol was added to a clear solution to allow for starch precipitation. The filtrate obtained was concentrated to the volume of 10 mL by evaporation on a BUCHI rotary evaporator. The concentrates produced were analyzed for the content of organic acids with the HPLC liquid chromatography method using a Hewlett-Packard 1100 chromatograph (Hewlett Packard, Wilmington, DE, USA). The degree of substitution was expressed as the percentage content of acid residues in the preparations. Swelling Power and Solubility of Starch Preparations in Water Having a Temperature of 80 \({}^{\circ}\)C  
In brief, 200 mL of an aqueous suspension containing 1 g starch preparations or modified starch preparations per 100 g solution were prepared in a round-bottom flask. The flask was placed in a water bath with shaking at a temperature of 80 \({}^{\circ}\)C. It was kept under these conditions for 30 min until the water bath temperature had been obtained inside it.