Sterol Oxidation in Ready-to-Eat Infant Foods During Storage

Abstract

The effect of storage on sterol oxidation of ready-to-eat infant foods was evaluated. Two different liquid infant foods (honey or fruits flavors), prepared with milk and cereals, were stored for 0, 2, 4, 7 and 9 months at 25°C. Sterol oxidation products (SOP) were isolated by cold saponification, purified by silica solid-phase extraction, and analyzed by gas chromatography (GC) and GC-mass spectrometry. -Sitosterol was the most representative sterol, followed by cholesterol and campesterol. No significant differences in the total and single SOP content (0.8-1 mg/kg of product) were observed with respect to storage time and type of sample; the main SOP found was 7-ketositosterol (<0.2 mg/kg of product). The extent of stigmasterol oxidation (2.9%) was higher than that of cholesterol (1.9%) and -sitosterol (1.4%). The type and quality of raw materials, as well as the processing conditions, seem to greatly influence SOP formation and accumulation in infant foods.

Stability of Sterols in Phytosterol-Enriched Milk under Different Heating Conditions

“…In milk-based infant foods, the extent of stigmasterol oxidation (2.9%) was higher than that of cholesterol (1.9%) and -sitosterol (1.4%) (49). In our work, the oxidation percentages obtained for each type of sterol (oxysterols/sterols × 100) ( Table 4) showed that -sitosterol and stigmasterol were the compounds least affected by the oxidation process, cholesterol being the one with the highest oxidation percentages in every sample.…”

Sterol stability in functional fruit beverages enriched with different plant sterol sources

“…In another study by our group, POP contents from β-sitosterol, stigmasterol and campesterol were determined in milk and cereal based infant foods (García-Llatas et al, 2008), resulting in 7-ketoderivatives of β-sitosterol > stigmasterol > campesterol. The total POP contents were low (0.9-16.1 μg of POPs/100 g of sample), though these foodstuffs were not enriched with PS.…”

“…However, few studies to date have identified and quantified POPs in other foods, and the existing publications mostly focus on high lipid content matrixes (Bortolomeazzi, Cordano, Pizzale, & Conte, 2003;Dutta, 2002;Soupas, Huikko, Lampi, & Piironen, 2007). In the case of dairy matrixes, 7-ketositosterol contents have been determined as an indicator of phytosterol oxidation in milk-based infant foods (Zunin, Calcagno, & Evangelisti, 1998), and several POPs have been quantified in milk-and cereal-based infant foods (García-Llatas et al, 2008). Plant sterol stability in enriched dairy products was determined for the first time by Soupas et al (2006), who reported POP contents in skimmed milk enriched with free or esterified PS.…”

Development and validation of methodologies for the quantification of phytosterols and phytosterol oxidation products in cooked and baked food products

“…In recent years, several studies were conducted on the analysis of foods added with PS such as spread, milk, yogurt drink, milkbased fruit beverage and fruit beverage [25][26][27][28]42]. These food items are relatively simple products that are consumed as such without further cooking being involved.…”

“…Both GC with flame ionization detection (GC-FID) as well as GC-mass spectrometry (GC-MS) have been widely used [13,23,24]. Several studies have been conducted on the analysis of the sterol content by GC in foods with added PS such as spread, milk, yogurt drink, milk-based fruit beverage and fruit beverage [24][25][26][27].…”