Histological analyses were performed by cryo-sectioning according to the method described by Ofstad et al. . Samples less than 0.5 cm 3 were frozen in liquid nitrogen, sectioned in 5 µm slides in a Leica cryostat (CM 3050S, Leica Biosystems, IL, USA), fixed in Bouin's fixative (Polysciences, Warrington, PA, USA) stained with Aniline Blue-Orange G Solution (26450-04, Electron Microscopy Sciences, Hatfield, PA, USA) in the ratio 1:10 for 4 min and mounted in glycerol. Using this technique, the collagen/gelatin was stained blue, and the myofibrillar proteins yellow, while the fat remained unstained. The slides were scanned with Aperio CS 2 (Leica Biosystems, Buffalo Grove, IL, USA) and digital images were taken with ImageScope_64 (Leica Biosystems, Buffalo Grove, IL, USA). For assessment of the fat distribution, sections from each sausage formulation were stained by Nile Red (Merck, Darmstadt, Germany) according to the method described by Ofstad et al. . Nile Red is highly soluble in oils and fluoresces when excited in the range 450-500 nm. The sections were stained at 4 °C over night, mounted using a pre-cooled glycerol solution and the slides were kept cold until examination. By using this staining method, smearing of fat globules was avoided. The slides were examined by using a light microscope (DM6000 B) and the Leica Application Suite X and DMC 4500 (Leica Microsystems, Wetzlar, Germany) were used to snap images. The images were visually inspected.