Raspberry Pomace as a Good Additive to Apple Freeze-Dried Fruit Bars: Biological Properties and Sensory Evaluation

Abstract

This study investigated the impact of adding raspberry pomace to the phenolic content and biological properties of freeze-dried apple/raspberry bars. The bars were prepared by replacing apple puree with raspberry pomace (5–50%), and their phenolic compounds were assessed using ethanol and buffer extracts. This work also explored the potential bioaccessibility of phenolic compounds in enriched bars through a simulated digestion process (digest). Antioxidant, anti-inflammatory (LOX, COX-2 inhibition), antihypertensive (ACE inhibition), and antiproliferative effects on AGS and HT-29 cancer cells were evaluated. The total polyphenol content was highest in the all bar variants post-digestion. The highest—904.26 ± 23.5 mg/100 g—was determined for the B50 sample In the enriched bars, the concentration of chlorogenic acid decreased from 6.99 ± 1.08 mg/L for BP5 to 2.75 ± 0.32 mg/L for BP50, but the ellagic acid concentration increased from 1.46 ± 0.02 mg/L for BP5 to 12.73 ± 0.09 mg/L for BP50. Among the tested extracts, the highest antioxidant and LOX, COX-2 inhibiting activity was determined for digest. The ability to neutralize free radicals increased with raspberry pomace addition from 3.63 ± 0.26 mM TE/100 g for BC to 5.58 ± 0.22 mM TE/100 g for the BP50 sample. ACE inhibition was quite similar for ethanolic and digest extracts, but much weaker for buffer extracts. The lowest EC50 value was 1.04 ± 0.03 mg/mL for the BP30 ethanolic sample. Analyzed extracts showed antiproliferative activity against both tested cell lines. The EC50 values for HT-29 cancer cells decreased from 0.354 ± 0.031 mg/mL for BC to 0.026 ± 0.006 mg/mL for the BP50 digest sample. It can be assumed that the BP30 bar best met the assumed criteria, and is optimal for both sensory quality (receiving an average score of 4.45) and health benefits.