title: Physicochemical evaluation of sheep milk yogurts containing different levels of inulin.
abstract: The present study aimed to evaluate the physicochemical parameters of sheep milk yogurt smoothies (SMY) containing inulin at different levels (0, 2, 4, and 6%). Titratable acidity and pH, yogurt bacteria counts, fatty acids profile, and healthy lipid indices were evaluated during 28 d of refrigerated storage. As expected for yogurts, Streptococcus thermophilus counts decreased 1 to 3 log cycles and Lactobacillus delbrueckii ssp. bulgaricus counts decreased 1 to 2 cycles from d 1 to 28. The protective effect of inulin on bacteria survival and viability in the food matrix was not verified in the prebiotic SMY during storage, regardless of inulin level. Although lower post-acidification was observed in prebiotic SMY due to inulin addition, no changes were verified in short-chain fatty acids (SCFA) or polyunsaturated fatty acids (PUFA). In contrast, an increase in medium- and long-chain fatty acids (MCFA and LCFA) and monounsaturated fatty acids (MUFA) was observed during storage in all SMY. The most significant levels of fatty acids in SMY were oleic acid, followed by palmitic and myristic acids. A high positive correlation between conjugated linoleic acid (CLA) and oleic acid (r=0.978) was observed. The cis-9,trans-11 CLA isomer represented approximately 78% of total PUFA and 2% of total fatty acids, whereas α-linoleic acid comprised about 22% PUFA and 1% of total fatty acids in SMY. The fatty acid changes during storage were associated with the metabolic activity of the starter bacteria, especially for oleic acid and cis-9,trans-11 CLA isomer. Thus, the SMY represented a great source of these compounds. We observed that inulin levels did not affect fatty acids. A nonsignificant decrease in atherogenic index was observed during storage in all SMY, and a positive correlation (r=0.973) was found between atherogenic index and thrombogenic index of SMY. High correlations were observed between lauric and myristic acids and saturated fatty acids (r=0.907 and r=0.894, respectively), providing evidence of their atherogenic and thrombogenic potential. A negative correlation was observed between stearic acid and atherogenic index (r=-0.612) and between oleic acid and atherogenic index. Sheep milk yogurt could be characterized as a food with low atherogenic and thrombogenic risk because of its healthy lipid composition. Therefore, addition of inulin to SMY could be a good option to improve functionality of this food matrix for dairy companies wishing to enter the functional food market.
authors.affiliation: Department of Food Technology, Veterinary College, Fluminense Federal University, 24230-340 Niterói, RJ, Brazil.
authors.forename: C F
authors.initials: CF
authors.lastname: Balthazar
authors.affiliation: Department of Food Technology, Veterinary College, Fluminense Federal University, 24230-340 Niterói, RJ, Brazil.
authors.forename: C A
authors.initials: CA
authors.lastname: Conte Júnior
authors.affiliation: Federal Institute of Education, Science and Technology of Rio de Janeiro, 20270-021 Rio de Janeiro, RJ, Brazil.
authors.forename: J
authors.initials: J
authors.lastname: Moraes
authors.affiliation: Department of Food Technology, Veterinary College, Fluminense Federal University, 24230-340 Niterói, RJ, Brazil.
authors.forename: M P
authors.initials: MP
authors.lastname: Costa
authors.affiliation: Federal Institute of Education, Science and Technology of Rio de Janeiro, 20270-021 Rio de Janeiro, RJ, Brazil.
authors.forename: R S L
authors.initials: RSL
authors.lastname: Raices
authors.affiliation: Department of Food Technology, Veterinary College, Fluminense Federal University, 24230-340 Niterói, RJ, Brazil.
authors.forename: R M
authors.initials: RM
authors.lastname: Franco
authors.affiliation: Federal Institute of Education, Science and Technology of Rio de Janeiro, 20270-021 Rio de Janeiro, RJ, Brazil.
authors.forename: A G
authors.initials: AG
authors.lastname: Cruz
authors.affiliation: Department of Food Technology, Veterinary College, Fluminense Federal University, 24230-340 Niterói, RJ, Brazil. Electronic address: adrianasilva@id.uff.br.
authors.forename: A C O
authors.initials: ACO
authors.lastname: Silva
mesh_terms: D000818:Animals; D005227:Fatty Acids; D007444:Inulin; D044243:Linoleic Acids, Conjugated; D008892:Milk / Q000737:chemistry; D010063:Ovum; D012756:Sheep; D048249:Streptococcus thermophilus / Q000378:metabolism; D015014:Yogurt / Q000382:microbiology*
chemical_list: D005227:Fatty Acids; D044243:Linoleic Acids, Conjugated; D007444:Inulin
keywords: acidity; atherogenic index; fatty acids; prebiotic; thrombogenic index