Citation: Shokraneh, N.; Alimi, M.; Shahidi, S.-A.; Mizani, M.; Bameni Moghadam, M.; Rafe, A. Textural and Rheological Properties of Sliceable Ketchup. Gels 2023, 9, 222. https:// doi.org/10.3390/gels9030222 Academic Editor: Aris Giannakas Received: 15 February 2023 Revised: 8 March 2023 Accepted: 10 March 2023 Published: 14 March 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). gels Article Textural and Rheological Properties of Sliceable Ketchup Nadia Shokraneh 1 , Mazdak Alimi 1, *, Seyed-Ahmad Shahidi 1, * , Maryam Mizani 2 , M. Bameni Moghadam 3 and Ali Rafe 4 1 Department of Food Science and Technology, Ayatollah Amoli Branch, Islamic Azad University, Amol P.O. Box 6616935391, Iran 2 Department of Food Science and Technology, Science and Research Branch, Islamic Azad University, Tehran P.O. Box 6616935391, Iran 3 Department of Statistics, Allameh Tabataba’i University, Tehran P.O. Box 1489684511, Iran 4 Department of Food Processing, Research Institute of Food Science and Technology (RIFST), Mashhad P.O. Box 91775-1163, Iran * Correspondence: ahooora_mazdak@yahoo.com or mazdak.alimi@iau.ac.ir (M.A.); sashahidy@yahoo.com or sa.shahidi@iau.ac.ir (S.-A.S.) Abstract: This study investigates the effect of different mixtures of gums [xanthan (Xa), konjac mannan (KM), gellan, and locust bean gum (LBG)] on the physical, rheological (steady and unsteady), and textural properties of sliceable ketchup. Each gum had an individually significant effect (p < 0.05) on viscosity; however, the addition of Xa in combination with other gums had a greater effect on viscosity. By increasing the use of Xa in ketchup formulations, the amount of syneresis decreased such that the lowest amount of syneresis related to the sample prepared with 50% Xa and 50% gellan. Although the use of different levels of gums did not have a significant effect on the brightness (L) and redness (a) indices (p < 0.05), the use of different ratios of gums had a significant effect (p < 0.05) on the yellowness (b) index. The effect of different levels of gums used had a significant effect only on firmness (p < 0.05), and their effects on other textural parameters were not statistically significant (p > 0.05). The ketchup samples produced had a shear-thinning behavior, and the Carreau model was the best model to describe the flow behavior. Based on unsteady rheology, G’ was higher than G” for all samples, and no crossover between G’ and G” was observed for any of the samples. The constant shear viscosity (η) was lower than the complex viscosity (η*), which showed the weak gel structure. The particle size distribution of the tested samples indicated the monodispersed distribution. Scanning electron microscopy confirmed the viscoelastic properties and particle size distribution. Keywords: sliceable ketchup; gum; viscoelastic; rheological properties; syneresis 1. Introduction Currently, market research shows a growing trend in ketchup consumption [1]. It is predicted that in the period from 2021 to 2025, the market for this type of product will have an annual growth of about 2.64%. Ketchup is a flavored product containing various ingredients produced from a combination of fresh tomatoes or concentrates in the form of puree or pastes with sweeteners, salt, vinegar, and spices [2]. This type of sauce is a non- Newtonian semisolid material with a yield stress that exhibits thixotropic and viscoelastic properties [3–6]. Ketchup is consumed with various foods such as ready meals, pasta, pizza, etc. One of the most widely used uses for ketchup is with meat products, such as sausages, and since these two types of foods are commonly consumed together, their combined use can be a unique and attractive topic. Currently, a mixture of hydrocolloids is used to improve physical and rheological properties and reduce costs [7]. Commercial ketchup usually is thickened with tomato pulp powder [7], potato or corn starch [8,9], modified starch and carboxymethylcellulose [10], guar, and carboxymethylcellulose and Xa [3,11]. Gels 2023, 9, 222. https://doi.org/10.3390/gels9030222 https://www.mdpi.com/journal/gels