Evaluation of In Vitro Antioxidant, Anti-Obesity, and Anti-Diabetic Activities of Opuntia ficus Cladodes Gel and Its Application as a Preservative Coating for Shrimp during Refrigerated Storage

Opuntia ficus cladodes (OFC) are considered one of the wastes that result from opuntia cultivation, and their disposal by traditional methods results in many environmental problems. Therefore, this study was conducted with two aims. The first was the production of OFC gel, and the evaluation of its in vitro antioxidant (by two methods, DPPH and ABTS), anti-obesity, and anti-diabetic activities. The second was an investigation of the effects of different concentrations of this gel (0, 50, and 100%) as an edible coating on the quality of shrimp during 8 days of refrigerated storage. The results showed that this gel was characterised by a high content of ash (10.42%), total carbohydrates (75.17%), and total phenols (19.79 mg GAE/g). OFC gel contained six types of sugars: arabinose, xylose, galactose, rhamnose, glucose, and uronic acid, and the most abundant was xylose (36.72%). It is also clear from the results that the OFC gel had high antioxidant properties, which were higher against DPPH than ABTS at the same concentration. OFC gel showed a high inhibition activity against lipase, α-glycosidase, and α-amylase enzymes, and their IC50 values were 1.43 mg/mL, 0.78 mg/mL, and 0.57 mg/mL, respectively. The results also stated that shrimp coated with OFC gel had lower pH, drip loss, TVB-N, and TBA values through the days of refrigerated storage. Moreover, the shrimp coated with 100% OFC gel were better than those coated with 50% OFC gel. In conclusion, OFC gel showed high potency as active antioxidant, for its enzyme anti-activities, and as an edible coating for shrimp.

Application of Gurma Melon (Citrullus lantus var. colocynthoides) Pulp-Based Gel Fat Replacer in Mayonnaise

Gurma melon pulp-based gel (GMPG) was examined as a fat replacement in mayonnaise. GMPG was used to partially replace fat in quantities of 25, 50, and 70%, abbreviated as GMPG-25, GMPG-50, and GMPG-70, respectively. Mayonnaise’s physicochemical and sensory properties were studied. The data demonstrated that all low-fat mayonnaises had much lower energy value but significantly higher water content than their full-fat equivalents and that these differences developed as GMPG replacement levels increased. A microstructure analysis revealed compact the packing structures of big droplets in the whole fat sample and a baggy structure network of aggregated tiny droplets in the GMPG-25, GMPG-50, and GMPG-70 samples. There were no significant differences in pH or water activity after one day of storage between the full-fat and low-fat mayonnaises. Mayonnaises with GMPG-50 and GMPG-70 exhibited the same hardness as full-fat, whereas mayonnaises with GMPG-25 were harder than the other samples. Increased mayonnaise whiteness (L* increase and a* and b* reduction) was seen with reductions in fat. All samples had good sensory approval, with the 50% oil mayonnaise appearing to be the most appealing. It has been demonstrated that GMPG is an effective fat replacement agent.