J Food Process Preserv. 2021;00:e15228. wileyonlinelibrary.com/journal/jfpp | 1 of 13 https://doi.org/10.1111/jfpp.15228 © 2021 Wiley Periodicals LLC. 1 | INTRODUCTION Lactobacilli generally used in the production of fermented food products such as yogurt, sauerkraut, pickles, and wine also function as a probiotic culture benefiting humans and animals by improving gut microbial balance. Lactobacilli are known to derive metabolic en- ergy from homofermentative or heterofermentative carbohydrate fermentation to accomplish its complex nutritional requirements (Didari et al., 2014; Makarova et al., 2006). Among many strains and species of lactobacilli which are used commercially as probiotics, Lactobacillus casei have been added to a variety of dairy-based prod- ucts such as fermented milks and yogurts (Hoppe & Larsen, 2009). L. casei is also studied in fermented soy milk (Kumari et al., 2018), vegetable and fruit juices (Martins et al., 2013), apricot juice (Bujna et al., 2018), etc. L. casei is a gram-positive, nonmotile, nonspore forming, and facultative heterofermentative strain which can entirely convert hexoses (Srinivas et al., 1990) into lactic acid via Embden– Meyerhof–Parnas (EMP) pathway. However, in the presence of com- plex carbohydrates or carbohydrate limiting environment, acetic acid and ethanol are formed in addition to butyric acid, formic acid, and lactic acid (Gobbetti & Minervini, 2014). L. casei has been iso- lated not only from traditional milk cultures around the world like Indonesian dadih, Indian Dahi, Ethiopian ititu, and Kenyan maziwa Lala, but also from olive fermentation, meats, sausages, wine, and Received: 15 June 2020 | Revised: 13 November 2020 | Accepted: 28 December 2020 DOI: 10.1111/jfpp.15228 ORIGINAL ARTICLE Effect of inulin and fructooligosaccharide supplementation on the growth and survival of Lactobacillus casei in model sugar systems Priyanka Parhi | Keang Peng Song | Wee Sim Choo School of Science, Monash University Malaysia, Bandar Sunway, Malaysia Correspondence Wee Sim Choo, School of Science, Monash University Malaysia, Bandar Sunway 47500, Selangor, Malaysia. Email: choo.wee.sim@monash.edu Funding information School of Science, Monash University Malaysia, 47500 Bandar Sunway, Selangor, Malaysia Abstract Inulin and fructooligosaccharides (FOS) are widely used prebiotics. In this study, model sugar systems such as glucose, fructose, lactose, and sucrose (2%, 3%, and 4%) were used to investigate the effect of inulin or FOS (0.5%, 1%, 2%, 3%, and 4%) supplementation on the growth and survival of Lactobacillus casei. The highest growth-promoting effect was observed with 2% lactose with 4% inulin or 4% FOS supplementation. Based on the highest percentage increase in growth index (GI) of L. casei, the most suitable sugar for inulin and FOS supplementation was lactose, fol- lowed by fructose and glucose. In growth assay, based on the percentage increase in GI, FOS (36.8%) was better than inulin (20.1%) for supplementation in the lactose system. In the glucose system, based on the percentage increase in GI, inulin (7.3%) was better than FOS (6.5%) for supplementation. Likewise, inulin (14.6%) was better than FOS (11.1%) for supplementation in fructose system. Practical applications Probiotics and prebiotics are popular functional ingredients that provides health ben- efits to the consumers. These two ingredients can be administered individually or together. Experimental results indicated that when prebiotics at different concentra- tions are supplemented with a probiotic, L. casei in various sugar systems, growth- promoting effect, partial inhibition or no effect on the growth and survival of the probiotic is found. These results serve as a guide for the application of prebiotic sup- plementation with L. casei in the food industry.