Effects of UV-C irradiation and traditional thermal processing on acemannan contained in Aloe vera gel blends

Evaluation of Acemannan in Different Commercial Beverages Containing Aloe Vera (Aloe barbadensis Miller) Gel

Aloe vera (Aloe barbadensis Miller) gel is a frequently used ingredient in many food pro-ducts, particularly beverages, due to its reported health benefits. Studies have identified acemannan, a polysaccharide rich in mannose units which are partially or fully acetylated, as the primary bioactive compound in Aloe vera gel. The acemannan content and its degree of acetylation (DA) were measured in 15 different commercial beverages containing Aloe vera at varying concentrations (from 30% to 99.8%) as listed on the label. Other biopolymers such as pectins, hemicelluloses, and cellulose were also evaluated. Flavoured beverages (seven samples labelled as containing from 30% to 77% Aloe vera) presented low levels of acemannan (<30 mg/100 g of fresh sample) and were fully deacetylated in most cases. These samples had high levels of other polymers such as pectins, hemicelluloses, and cellulose, likely due to the addition of fruit juices for flavour. Unflavoured beverages (eight samples, with Aloe vera concentrations above 99% according to their labels) had variable levels of acemannan, with only three containing more than 160 mg/100 g of fresh sample. In fact, four samples had less than 35 mg acemannan/100 g of fresh sample. DA levels in all but one sample were lower than 35%, possibly due to processing techniques such as pasteurization causing degradation and deacetylation of the acemannan polymer. Legislation regarding Aloe vera products is limited, and manufacturers are not required to disclose the presence or quality of bioactive compounds in their products, leaving consumers uncertain about the true properties of the products they purchase.

Physical, Chemical and Microbiological Properties during Storage of Red Prickly Pear Juice Processed by a Continuous Flow UV-C System

The effects of pH (3.6 and 7.0) and irradiation UV-C dose irradiation (0, 9.81, 15.13, and 31.87 mJ/cm2) on the physicochemical properties and natural microbiota of red prickly pear juice were evaluated during processing and storage. Thermal treatments were used as the control applying high temperatures for a short time (HTST 80 °C/30 s) or ultra-high temperature (UHT 130 °C/3 s). UV-C treatments applied to juices with both pHs inactivated coliforms and mesophiles with the same efficacy as thermal treatments. Yeasts and molds were inactivated at a dose of >15.13 mJ/cm2 at both pHs. The UV-C doses showed no differences in betalains, polyphenols, or antioxidant activity. However, a decrease in these compounds was observed during storage. The lowest reductions in betacyanins (11.1–16.7%) and betaxanthins (2.38–10.22%) were obtained by UV-C treatment at pH 3.6. Thermal treatments (HTST and UHT) caused a reduction greater than UV-C irradiation in betacyanins, betaxanthins, polyphenols, and antioxidant activity after treatment. However, after storage at pH 3.6, the contents of these compounds reached those of the UV-C treatments, except for polyphenols. In specific pigments, betanin retention was highest at pH 3.6 (62.26–87.24%), and its retention decreases with UV-C dose increase and storage. The indicaxanthin retentions were higher (75.85–92.27%) than those of betanin, and the reduction was mainly due to storage. The physical properties (pH, acidity, and °Brix) were not affected by treatments, except for the color. The results suggest that a dose of 15.13 mJ/cm2 of a continuous UV-C system is a non-thermal alternative for the processing of red prickly pear juice at pH 3.6, preserving its properties.

Immunobiology and Application of Aloe Vera-Based Scaffolds in Tissue Engineering

Aloe vera (AV), a succulent plant belonging to the Liliaceae family, has been widely used for biomedical and pharmaceutical application. Its popularity stems from several of its bioactive components that have anti-oxidant, anti-microbial, anti-inflammatory and even immunomodulatory effects. Given such unique multi-modal biological impact, AV has been considered as a biomaterial for regenerative medicine and tissue engineering applications, where tissue repair and neo-angiogenesis are vital. This review outlines the growing scientific evidence that demonstrates the advantage of AV as tissue engineering scaffolds. We particularly highlight the recent advances in the application of AV-based scaffolds. From a tissue engineering perspective, it is pivotal that the implanted scaffolds strike an appropriate foreign body response to be well-accepted in the body without complications. Herein, we highlight the key cellular processes that regulate the foreign body response to implanted scaffolds and underline the immunomodulatory effects incurred by AV on the innate and adaptive system. Given that AV has several beneficial components, we discuss the importance of delving deeper into uncovering its action mechanism and thereby improving material design strategies for better tissue engineering constructs for biomedical applications.

Continuous Flow UV-C Irradiation Effects on the Physicochemical Properties of Aloe vera Gel and Pitaya (Stenocereus spp.) Blend

Physicochemical properties of a blend of 10% Aloe vera gel with 5% pitaya juice subjected to UV-C doses of 16.5, 27.7, and 40 mJ/cm2 were evaluated at pH 3.5 and 5.5. Unprocessed treatments were used as the control. The a* color parameter decreased and luminosity increased at pH 3.5. The decrease in the reddish color was consistent with the decrease in total betalains content and stabilized at pH 5.5. The NMR analyses of UV-C treatments showed changes in betalains signal patterns. Polyphenolics content was significantly reduced in the UV-C treatments at pH 5.5. UV-C processing decreased the antioxidant activity 1.25 times compared to unprocessed treatments. Total sugar content was reduced as the UV-C dose increased. Doses above 16.5 mJ/cm2 resulted in a higher simple sugar content at a pH 3.5. The UV-C continuous flow technology can be applied to stabilize betalains in Aloe vera-pitaya blends at a UV-C dose of 16.5 mJ/cm2 and pH 5.5.