Drying efficiency and quality preservation of blackberries (Rubus spp. variety Tupy) in the near and mid-infrared-assisted freeze-drying

• Published in: Food chemistry advances Vol. 3; p. 100550
• Main Authors: Oliveira, Natália Leite, Alexandre, Ana Cláudia Silveira, Silva, Sérgio Henrique, Figueiredo, Jayne de Abreu, Rodrigues, Adrise Aparecida, de Resende, Jaime Vilela
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-12-2023; Elsevier
• Subjects: Bioactive compounds; Drying kinetics; Infrared radiation-assisted freeze-drying; Microstructure; Texture profile analysis; Texture profile analysis; Microstructure; Bioactive compounds; Infrared radiation-assisted freeze-drying; Drying kinetics
• ISSN: 2772-753X; 2772-753X
• DOI: 10.1016/j.focha.2023.100550

•Freeze-drying assisted by infrared heating (IRFD) reduced (∼43 %) the drying time.•Drying by IRFD did not affect the color of dried blackberries.•Logarithmic, Page, and Newton models had a good fit for whole blackberries drying.•Dried blackberry using near wavelength had the highest rehydration ratio over time.•Near wavelength proved to be more effective than the far wavelength in IRFD.
The influence of infrared radiation-assisted freeze-drying (IRFD) on the process efficiency and quality of blackberries (Rubus spp. variety Tupy) was evaluated. Two lamp types were coupled in the freeze dryer to produce short-wavelength (NIRFD) and mid-wavelength (MIRFD). Treatments were: conventional freeze-drying (FD - control); continuous NIRFD, continuous MIRFD; NIRFD and MIRFD applied after 40 % weight reduction. IRFD reduced up to 42.51 % the drying time compared to FD, and NIRFD were the fastest treatments due to the greater penetration depth. ANOVA results of shrinkage, total color difference and hue angle were not significant (P < 0.05) and indicate that final volume reductions were not affected after IRFD and the surface colors were preserved with the same characteristic red color (mean hue of 32.9°) of FD. Results for hardness, total phenolic content (TPC), antioxidant capacity (AC) and anthocyanin content of freeze-dried blackberries were statistically different (P < 0.05) when using IRFD. MIRFD had higher hardness (10.13 N) compared to FD (6.98 N) and this result influenced the lower rehydration ratio. MIRFD also reduced the anthocyanin content. NIRFD significantly yielded higher values for TPC and has potential for the production of dried blackberries with good appearance, high nutritional content and faster rehydration capacity.
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