_Article_  
**Osmotic Dehydration for the Production of Novel Pumpkin Cut Products of Enhanced Nutritional Value and Sustainability**  
**[PERSON] *, [PERSON], [PERSON] and [PERSON] Laboratory of Food Chemistry and Technology 5, School of Chemical Engineering, National Technical University of Athens, Iroon Polytechnioui, Polytechnioupoli Zografou, 15780 Athens, Greece; [EMAIL_ADDRESS] (E.P.); [EMAIL_ADDRESS] (V.A.); [EMAIL_ADDRESS] (P.T.)**  
* Correspondence: [EMAIL_ADDRESS]; Tel.: +30-210-7723118 check for updates  
Received: 6 August 2020; Accepted: 3 September 2020; Published: 8 September 2020  
**Featured Application: Strained Yoghurt (SY) Whey (acid whey) is a by-product of nutritional value that cannot be easily utilized by the industry. The limitations (low pH, high Biochemical Oxygen Demand (BOD)) have caused SY Whey to be directed toward non-food uses, and valuable nutrients of the whey remain outside the human consumption channel. The reintroduction of SY Whey into the food chain would improve sustainability of Greek yoghurt production. The use of SY Whey as an osmotic solvent during the osmotic dehydration of fruits and vegetables can contribute towards that direction. The osmotic behavior of SY Whey (as osmotic solvent along with other ingredients: galacto-oligosaccharides, trehalose, ascorbic acid) showed that SY Whey can lead to the production of high quality semi-dried or dried (pumpkin) products for uses such as snack foods or other food formulations (muesli, dairy products). It could be concluded that the pasteurized SY Whey could be used as an alternative osmotic solute for the partial dehydration of fruits (in this study pumpkin) not affecting the sensory characteristics of the final osmosed fruit product.**  
**Abstract: The quality and preservability of fresh-cut fruits can be improved by osmotic dehydration (OD). In this study, the impact of Strained Yoghurt Whey (SY Whey) (along with other osmotic solutes) on mass transfer kinetics (water loss, solid gain, water activity decrease), quality attributes (color, texture, sensory characteristics, vitamin C), and microbial stability during OD and subsequent refrigerated storage (5-15 \({}^{\circ}\)C) of OD-processed pumpkin cuts was studied. The effect of temperature (35-55 \({}^{\circ}\)C), time (10-240 min), and type of osmotic solvent was evaluated to select the optimal processing conditions (55 \({}^{\circ}\)C-120 min; WL: 9-99-10.86 g w,/g i.d.m. SG: 1.47-1.79 g s/g i.d.m., \(a_{w}\): 0.89). The use of SY Whey vs. water as solvent enhanced the mass transfer phenomena increasing the solids uptake diffusion coefficient by 20%. Water and whey osmosed samples were of similar quality (32-38% increase of hardness, total sensory quality score: 7.9-8.2/9.0, vitamin C content: 77-81 mg/100 g). At all studied storage temperatures, OD\({}_{\text{SY Whey}}\) samples presented lower quality degradation rates compared to the respective OD\({}_{\text{Water}}\) samples (e.g., almost half for hardness change). The shelf life of both OD processed pumpkin cuts exceeded 90 days at 5-15 \({}^{\circ}\)C (no microbial growth) supporting the applicability of SY whey as novel osmotic solvent.**  
**Keywords:**_Cucurbita pepo_ L.; strained yoghurt whey; osmosis; mass transfer; quality modelling