ABSTRACT
Three plant sterol (PS)-enriched beverages, milk based fruit juice (MFJPS), fruit juice (FJPS) and milk beverage (MPS), were stored at 4, 24, or 37 °C and analysed at regular time intervals of 2 months until 6 months. PS stability was analysed from the production of phytosterol oxidation products (POPs). The ß-sitosterol oxides (7α/7ß-hydroxy, ß/α-epoxy, triol, and 7-keto) and campesterol oxides (ß/α-epoxy, and 7-keto) were detected in all beverages and at all storage times and temperatures. Total POP contents followed the order MPSâ«FJPS>MFJPS. In general, the beverages showed low PS oxidation levels (<0.17%). Predictive models of POP content versus storage time were established. These models explain total POP content by over 75% and individual POP content by over 50%. We propose 7-ketositosterol and 7-ketocampesterol as PS oxidation markers during storage of beverages of this kind.
Subject(s)
Beverages/analysis , Food Additives/chemistry , Milk/chemistry , Oxides/chemistry , Phytosterols/chemistry , Animals , Cattle , Food Storage , Oxidation-ReductionABSTRACT
Plant sterols (PS) stability, antioxidant parameters, and color were studied during 6 months of storage at 4, 24, and 37 °C in three PS-enriched functional beverages. Beverages were skimmed milk with fruit juice and PS (MFJPS), fruit juice and PS (FJPS), and skimmed milk with PS (MPS). No loss in total PS content occurred during storage observing the same values at any given storage time point. Total carotenoids decreased 36% with storage at two months and then remained stable. Total polyphenols showed fluctuations throughout the storage, remaining stable at 6 months and reaching initial values. The antioxidant capacity (TEAC method) increased 18% at 6 months, and there was an increase in color over time and temperature, probably due to Maillard reaction compound formation. The increase in total antioxidant capacity might have helped PS maintenance throughout storage, these beverages being a good PS source even after 6 months of storage.
Subject(s)
Antioxidants/analysis , Beverages/analysis , Food Storage , Food, Fortified/analysis , Phytosterols/analysis , Antioxidants/chemistry , Dairy Products/analysis , Fruit/chemistry , Phytosterols/chemistry , SpainABSTRACT
The content of plant sterol (PS) and their oxidation products (POPs) in eight ingredients used to enrich functional foods was studied. A gas chromatographic (GC) technique with mass-spectrometric detection was used for identification, while GC with a flame ionization detector (GC-FID) was used for quantification. ß-Sitosterol was the most abundant phytosterol, and the main POPs found were derived from this compound (7α/ß-hydroxysitosterol, 7-ketositosterol, and sitostanetriol). The total amount of POPs found in the ingredients ranged from 29.03 to 110.02 µg/100 g PS. The ß-sitosterol oxidation rates ranged from 10 to 50 µg ß-sitosterol oxides/100 g of ß-sitosterol. In view of this low rate of oxidation in the ingredients tested, it can be concluded that the PS remain stable in these ingredients. Significant correlations (p < 0.01) were found between total oxysitosterols versus ß-sitosterol contents (R(2) = 86.5%) and between total POPs and total PS (R(2) = 81.6%).
