This study investigated the influence of drying techniques such as convection hot-air drying, vacuum drying, and freeze drying with slow and flash pre-freezing on the total phenolic content and the profile of dominant phenolic compounds in cultivated blueberry (Vaccinium corymbosum L.). Although fresh blueberries exhibited higher total phenolic content (1350.85 mg GAE/100 g), total flavonol glycosides (66.20 mg/100 g), and total anthocyanins (218.23 mg/100 g) compared with dried samples, freeze-dried samples, particularly those subjected to flash pre-freezing, retained higher contents of these components in the dried material compared to other drying techniques. This could be attributed to the microstructural preservation of plant tissue during freeze drying. Furthermore, the study demonstrated that subsequent milling of freeze-dried samples, whether using a knife mill or a ball mill, also affects the availability of bioactive compounds in freeze-dried blueberry powders. The combination of flash pre-freezing followed by ball milling yielded the highest availability of bioactive components in the processed blueberry powder.

Crackers and cookies have become the most widely consumed snacks due to their low production costs, long shelf life, and ability to deliver essential nutrients. Increasing consumer health consciousness has shifted preferences toward foods perceived as natural and beneficial. This shift elevates demand for cracker formulations with novel, health-promoting natural ingredients. This study examined the effects of incorporating freeze-dried olive leaf powder (FDOLP) into crackers on their physicochemical properties, phenolic and volatile compound profiles, antioxidant capacity, and sensory acceptability. Total polyphenol content of crackers was determined using the Folin–Ciocalteu method, while antioxidant capacity was evaluated by FRAP and DPPH assays. The UHPLC-ESI-HRMS analysis evaluated olive-derived compounds, including tyrosol, oleuropein derivatives, and pinoresinol 4-O-glucoside, present in olive leaf-enriched crackers. The characterisation of volatile compounds in crackers was performed using headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME/GC-MS). A darker colour was observed in the enriched crackers compared to the control samples. Results demonstrated that increasing the proportion of FDOLP led to enhanced phenolic composition and antioxidant activity, as well as changes in the volatile profile of the crackers. Sensory analyses indicated that crackers enriched with moderate levels of FDOLP maintained acceptable overall sensory scores, suggesting a potential for the development of functional snacks. These findings demonstrate that olive leaves can be effectively utilised as a natural functional ingredient in cracker formulations to enhance their nutritional value and bioactive properties.