Utilization of prickly pear (Opuntia ficus-indica) fruit in functional food products

The study aims to evaluate the physicochemical, textural, sensory, and microbiological properties of functional food products, namely pestil and probiotic ice cream including Opuntia ficus-indica. Pestil production was carried out using two different gelling agents (5% wheat starch and 5% maltodextrin) and three different drying methods (hot air at 60°C, 100 W microwave + hot air at 60°C, 180 W microwave + hot air 60°C). Dried pestils were stored at +4°C for three months, and changes that occurred in the pestils' physicochemical, textural, and sensory properties during storage were investigated. During storage, the moisture, water activity, ash, pH, and thickness values of the pestils were in the range of 10,09-13-57%; 0,46-0,61; 3,57-4,57%; 5,89-6,00; and 0,53-0,65 mm, respectively. The storage had no statistically significant (p>0,05) effect on the moisture (%), water activity, total ash (%), pH, or pestil thickness values. The betalain, total phenolics, total flavonoids contents and free radical scavenging activities of pestil samples ranged from 0,43 to 0,59 μg/g, 18,29 to 35,79 mg GAE/100 g, 10,47 to 20,54 mg catechin/100 g, and 2,36 to 2,89 μm TE/g (d.w.b.), respectively. Changes in total phenolics contents, total flavonoids contents, betalain contents, and free radical scavenging activities of pestils during storage were statistically significant (p<0,05). It was determined that the pestil dried at 60°C for 90 minutes after drying at a 180W microwave power level for 90 seconds had the highest total phenolic and betalain contents as well as the greatest free radical scavenging activity. It has been found that pestil with wheat starch had the highest total phenolic and betalain contents, while pestil containing maltodextrin had the highest free radical scavenging activity. Drying using microwave oven for 90 s at 100W and 180W reduced the drying time by 50% (90 min), which was 180 min for hot- air drying at 60°C. Probiotic ice cream was produced by adding fruit pulp and pestil pieces along with probiotic starter cultures (Lacticaseibacillus rhamnosus and Bifidobacterium animalis subp. lactis BB-12) to improve the functional properties of ice cream. Three types of ice cream, namely control, fruit-added, and pestil pieces-added, were produced in two replicates by adding 2% probiotic bacteria (1:1 ratio), 15% fruit pulp, and 10% pestil pieces, each measuring 1 cm by 1 cm. Chemical, microbiological, and sensory analyses of the ice creams were carried out on days 0, 15, 30, and 60 during a 60-day storage period. The results were evaluated statistically. Dry matter, total ash, titratable acidity (lactic acid%), and pH values of the ice creams were 27,45–34,05%, 0,72-0,79%, 0,31–0,35%, and 6,46–6,48, respectively. The effects of ice cream type on dry matter, ash, and titratable acidity values were found to be statistically significant (p<0,05), while it was insignificant (p>0,05) for pH. In the study, a decrease in the L* value and an increase in the a* and b* values (due to fruit color) of ice creams containing fruit pulp and pestil pieces were observed. It was determined that the probiotic effect level was maintained in the samples during 60 days (>107 log cfu/g). In sensory evaluation, fruit ice cream received the highest score in terms of color and appearance from the panelists. No statistical difference (p >0,05) was observed between the sensory scores of the control group and fruit ice cream samples, which received the highest score in texture and consistency, taste, and odor attributes. In conclusion, the production of pestil and probiotic ice cream rich in functional ingredients from the nutritious prickly pear has been successfully carried out. The obtained products have created ideas for the food industry for development of healthy and delicious alternative products. Additionally, new data about functional foods produced with prickly pear has been introduced to the literature.