The kinetics of both conventional (mechanical stirring, 200rpm) and acoustic (55±5kHz, 435±5W/L) aqueous extraction of total phenolic content and antioxidant capacity from grape pomace by-products (Vitis vinifera L.) have been experimentally evaluated and modeled at different extraction temperatures (20, 35 and 50°C). A gradual and significant increase of total phenolic content and antioxidant capacity of the extracts was observed as the temperature increased, the highest values being obtained in the case of the extraction assisted acoustically. According to the results, the acoustic assistance of the extraction process led to aqueous extracts with phenolic and antioxidant characteristics similar to those obtained with mechanical stirring, working under lower temperature conditions and during less operating time. Specifically, the conventional extraction of total phenolics at 35 and 50°C did not differ significantly from extractions assisted with power ultrasound at 20 and 35°C, respectively; and the acoustic process required approximately 3, 4 and 8 times less time, at 20, 35 and 50°C, than the conventional extraction to obtain extracts with similar characteristics. The extraction curves obtained for total phenolic content and antioxidant capacity, measured by the ABTS and FRAP methods, were properly represented by a modified Weibull model for both conventional and acoustic extractions within the temperature range 20-50°C, presenting an average percentage of explained variance⩾97.9%, and an average mean relative error⩽7.0%. A high correlation (r(2)⩾0.992) was observed between the experimental and simulated values for all the quality attributes in study.

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(. Miller) is probably one of the most popular plants, widely studied because of numerous properties associated with the polysaccharides present in its gel. In particular, two main types of bioactive polysaccharides can be distinguished in the . gel: an acetylated mannose-rich polymer that functions as storage polysaccharide, and a galacturonic acid-rich polymer as the main component comprising the cell walls of the parenchymatous tissue. Interestingly, most of the beneficial properties related to the aloe plant have been associated with the acetylated mannose-rich polysaccharide, also known as acemannan. However, the composition and structural features of these polysaccharides, as well as the beneficial properties associated with them, may be altered by different factors, such as the climate, soil, postharvest treatments, and processing. Further, different analytical methods have been used not only to identify but also to characterize the main polysaccharides found in parenchyma of leaf. Within this context, the main aim of this review is to summarize the most relevant information about the structural and compositional features of the main polysaccharides found in the gel as well as the most relevant analytical techniques used for their identification and their influence on the technological, functional, and beneficial properties related to the plant.

Aloe mucilages of Aloe ferox (A. ferox) and Aloe vera (A. vera) were spray-dried (SD) at 150, 160 and 170 °C. Polysaccharide composition, total phenolic compounds (TPC), antioxidant capacity and functional properties (FP) were determined. A. ferox polysaccharides were comprised mainly of mannose, accounting for >70% of SD aloe mucilages; similar results were observed for A. vera. Further, an acetylated mannan with a degree of acetylation >90% was detected in A. ferox by 1H NMR and FTIR. SD increased the TPC as well as the antioxidant capacity of A. ferox measured by both ABTS and DPPH methods, in particular by ~30%, ~28% and ~35%, respectively, whereas in A. vera, the antioxidant capacity measured by ABTS was reduced (>20%) as a consequence of SD. Further, FP, such as swelling, increased around 25% when A. ferox was spray-dried at 160 °C, while water retention and fat adsorption capacities exhibited lower values when the drying temperature increased. The occurrence of an acetylated mannan with a high degree of acetylation, together with the enhanced antioxidant capacity, suggests that SD A. ferox could be a valuable alternative raw material for the development of new functional food ingredients based on Aloe plants.

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.