Toward gentle chokeberry juice production by ultrasound-assisted enzymatic maceration.

Sustainable processes accompanied by high extraction yields and minimized amounts of by-products are a major goal of current fruit juice production. Controlled degradation of cell wall polysaccharides, in particular pectin, may contribute to reduced emergence of side streams. Possible strategies for the optimization are the selection of enzyme preparations based on comprehensive studies of their activities, the adjustment of maceration temperature toward more gentle conditions, and the application of alternative technologies such as ultrasound (US) during maceration. The present study provides insights into the effects of ultrasound-assisted enzymatic maceration (UAEM) on pectin degradation, total anthocyanin content, thermal and storage stability, and juice yield during chokeberry juice production on pilot-plant scale. The two enzyme preparations applied predominantly possessed polygalacturonase or pectin lyase activity. Cell wall polysaccharide degradation was improved by US and resulted in a 3% increase in juice yield by UAEM using an enzyme preparation that shows mostly polygalacturonase activity. Thermostability of anthocyanins was improved in juices produced using pectin lyase and applying US and matched the stability of anthocyanins in juices produced using polygalacturonase. Storage stability of anthocyanins was improved in juice produced using polygalacturonase during UAEM. UAEM also resulted in lower yields of pomace making the production more resource-efficient. Overall, the use of polygalacturonase has promising potential to advance conventional chokeberry juice production by applying US at gentle conditions.

Aroma-Active Compounds in Robusta Coffee Pulp Puree-Evaluation of Physicochemical and Sensory Properties.

Wet coffee processing generates a large amount of coffee pulp waste that is mostly disposed of in the processing units. To reduce this waste and the associated environmental burden, an alternative strategy would be to exploit the coffee pulp to produce a durable and stable consumable product. Accordingly, a puree produced from Robusta coffee pulp was investigated in relation to its physicochemical and sensory properties. After thermal and chemical stabilization, the obtained puree (pH 3.6) was found to exhibit a multimodal particle size distribution, shear-thinning behavior, and lower discoloration, as well as an antioxidant capacity of 87.9 µmolTE/gDM. The flavor of the puree was examined by sensory evaluation and the corresponding analyses of aroma-active volatile compounds, as determined using aroma extract dilution analyses (AEDA) and gas chromatography-mass spectrometry/olfactometry (GC-MS/O). The puree was characterized by dominant fruity (4.4), floral (3.4), citrusy (3.3) and hay-like (3.3) odor impressions. The aroma-active compounds were predominantly aldehydes, acids, and lactones, whereby (E)-ß-damascenone, geraniol, 4-methylphenol, 3-hydroxy-4,5-dimethylfuran-2(5H)-one, and 4-hydroxy-3-methoxybenzaldehyde exhibited the highest flavor dilution (FD) factor (1024), thereby indicating their high impact on the overall aroma of the puree. This study demonstrates an approach to stabilize coffee pulp to produce a sweet, fruity puree with comparable physical properties to other fruit purees and that can be used as a new and versatile flavoring ingredient for various food applications.