Stabilisation of betalains and phenolic compounds extracted from red cactus pear (Opuntia ficus-indica) by spray and freeze-drying using oca (Oxalis tuberosa) starch as drying aid.

The objective of this work was to evaluate the stabilisation of betalains and phenolic compounds extracted from red cactus pear by spray and freeze-drying. After hydroethanolic extraction and partial solvent removal under reduced pressure, the highly coloured extracts were enriched with oca starch and maltodextrin as drying aids in different ratios (100:0, 70:30, and 50:50, oca starch: maltodextrin) prior to spray and freeze-drying. The obtained microencapsulated extract powders were characterised by moisture content, hygroscopicity, solubility and morphology. In addition, the stability of the encapsulated betalains and phenolics was evaluated during storage at room temperature for 105 days. All microcapsules showed high retentions of betacyanins (69.9-86.5% after 105 days), betaxanthins (72.2-81.9%), phenolic compounds (46.5-63.5%) and antioxidant capacity (60.1-64.9%, FRAP method; 49.7-57.5%, ABTS method). The system with 70:30 starch:maltodextrin ratio as drying aids showed the highest values of retention regarding the polyphenol content (63.5%), antioxidant capacity (64.9% to FRAP method) and betacyanin content (86.5%), as well as a low degradation rate constant of betacyanins (1.23 × 10-3 days-1) and a long half-life (563 days). Oca starch used alone or in combination with maltodextrin has been shown to work adequately as a microencapsulating agent and stabilizer of pigments and antioxidants derived from red cactus pear.

Yacon (Smallanthus sonchifolius): a functional food.

Yacon (Smallanthus sonchifolius) is an Andean tuberous root that is regarded as a functional food given that it contains fructooligosaccharides (FOS), inulin and phenolic compounds. The consumption of FOS and inulin improves the growth of bifidobacteria in the colon, enhances mineral absorption and gastrointestinal metabolism and plays a role in the regulation of serum cholesterol. Furthermore, the literature reports that the consumption of these prebiotics promotes a positive modulation of the immune system, improving resistance to infections and allergic reactions. Certain studies have demonstrated the potential of yacon as an alternative food source for those patients with conditions that require dietary changes. This review intends to describe the potential of yacon as a prebiotic and its cultivation and industrial processing for human consumption.