Stirred yogurt added with beetroot extracts as an antioxidant source: Rheological, sensory, and physicochemical characteristics

Effect of retrograded starch with different amylose content on the rheological properties of stored yogurt

Resistant starch (RS) promotes health benefits; however, when added to foods, it could change the rheological properties. The effect of adding different concentrations (2.5, 5, 7.5, and 10%) of retrograded corn starch with 27% (RNS) or 70% (RHS) amylose content on the properties of yogurt was evaluated through measurements of flow behavior and gel structure. Syneresis and resistant starch content were also assessed. Results were analyzed using multiple regression to describe the effect of starch concentration and storage time on the properties of yogurt added with RNS or RHS. Syneresis was reduced, RNS reinforced the structure increasing the water absorption capacity and the consistency index; meanwhile, RHS provided a yogurt containing up to 10 g of RS in 100 g of sample, allowing obtaining a functional dairy product. Creep-recovery test showed that adding RNS or RHS favored the matrix conformation, and the yogurt samples were able to recover. The final product behaved like a solid material with a firmer and more stable gel structure, resulting in a strengthened gel without weakening the yogurt structure, showing a characteristic like Greek-style or stirred yogurt depending on the type and concentration of retrograded starch.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05735-x.

Sensorially accepted Mangifera indica and Myrciaria dubia yogurts with high ascorbic acid content

Ascorbic acid deficiency has been associated with several health conditions. The objective of this study was to evaluate the content of ascorbic acid and the sensorial qualities of Mangifera indica and Myrciaria dubia yogurts. Four yogurt treatments were elaborated with different concentrations of these fruits (T1: 15% and 5%; T2: 15% and 10%; T3: 20% and 5% and T4: 20% and 10%) respectively, compared with a control treatment (CT: yogurt with 15% of Fragaria vesca). The ascorbic acid contents of the different treatments were determined by spectrophotometry, with values in the following order (T1: 63.2 mg/100 g; T2:114.3 mg/100 g; T3: 57.3 mg/100 g; T4: 115.1 and the control treatment CT:11.5 mg/100 g). The sensorial evaluation consisted of the application of a hedonic scale of 5 points (1: I dislike it very much; 2: I dislike it; 3: I neither like it nor dislike it; 4: I like it; 5: I like it a lot), results show evidence that the acidity level had a significant influence during the sensory evaluation. Treatment (T3) showed the greatest preference. The use of Mangifera indica and Myrciaria dubia in the treatments studied ensured ascorbic acid concentrations compared to the control treatment. This was significantly appreciated by consumers when the percentage of Myrciaria dubia was less than 10% of the total mass of the yogurt.

Effect of Encapsulated Beet Extracts (Beta vulgaris) Added to Yogurt on the Physicochemical Characteristics and Antioxidant Activity

Beet has been used as an ingredient for functional foods due to its high antioxidant activity, thanks to the betalains it contains. The effects of the addition of beet extract (liquid and lyophilized) on the physicochemical characteristics, color, antioxidant activity (AA), total betalains (TB), total polyphenols (TP), and total protein concentration (TPC) were evaluated on stirred yogurt. The treatments (T1-yogurt natural, T2-yogurt added with beet juice, T3-added extract of beet encapsulated with maltodextrin, and T4-yogurt added with extract of beet encapsulated with inulin) exhibited results with significant differences (p < 0.05). The highest TB content was observed in T2 (209.49 ± 14.91), followed by T3 (18.65 ± 1.01) and later T4 (12.96 ± 0.55). The highest AA was observed on T2 after 14 days (ABTS˙ 0.819 mM TE/100 g and DPPH˙ 0.343 mM TE/100 g), and the lowest was found on T1 at day 14 (ABTS˙ 0.526 mM TE/100 g and DPPH˙ 0.094 mM TE/100 g). A high content of TP was observed (7.13 to 9.79 mg GAE/g). The TPC varied between 11.38 to 12.56 µg/mL. The addition of beet extract significantly increased AA in yogurt, betalains being the main compounds responsible for that bioactivity.