Impact of drying processes on properties of polyphenol‐enriched maple sugar powders

Abstract

The aim of this research was to develop a natural food ingredient based on maple sugar powders (MSP) enriched in polyphenols. By incorporating 0.01% (wt/vol) of hot water extract (hot water extraction: 90°C and 1 hr; bark/water, 1/10 wt/vol) from sugar and red maple bark into substandard quality maple syrup, the latter was enriched by 13–20% in total phenolic content (TPC). The mixtures (syrup and extracts) were dehydrated using freeze‐drying (FD: at −36°C for 15 hr and subsequently at 30°C for 10 hr) or vacuum double‐drum drying (VDD: at 80°C and 660 Torr) to obtain the powders. Influence of drying processes on TPC, antioxidant capacity, and physical properties of powders was studied. Both drying processes caused a decrease in TPC and antioxidant capacity of MSP. Nevertheless, bark extracts contributed to higher TPC (8–10%) and antioxidant capacity (>40%) compared to control MSP. The moisture content of VDD powders (0.63–0.71%, dry basis) was significantly lower than that of FD powders (4.10–4.40%, dry basis). MSP produced by FD were amorphous and those produced by VDD crystalline. FD powders had instant‐like properties (dissolution time of 12–13 s), whereas those produced by VDD were less cohesive (Hausner ratio, 1.13–1.21), with excellent flowability. Practical Applications Consumers are increasingly attracted by natural food products. Canada is the world major producer of maple syrup, a nutritious natural sweetener exclusively obtained from maple trees sap. Unfortunately, a “very dark” color syrup is accumulated as surplus in large quantity in Canada as it is considered of substandard quality. In this research, freeze‐drying (FD) and vacuum double‐drum drying (VDD) techniques were studied to produce maple sugar powders (MSP) from this substandard surplus syrup. This syrup was additionally enriched in polyphenols by adding hot water extracts from maple barks. The obtained polyphenol‐enriched MSP have shown interesting qualities for application as natural sweeteners, such as free flowing or instant‐like powder. Our results indicate that FD and VDD are suitable techniques for substandard syrup conversion into value‐added maple product. MSPs have a huge potential of application as natural food ingredients of instant drinks, cereal mix, cookies, and energy bars.

Nutrient-Dense Shelf-Stable Vegetable Powders and Extruded Snacks Made from Carrots and Broccoli

“…This is due to the long duration of exposure of the product (48 h) to the environment while at a low temperature during freeze drying, compared to the short duration of exposure of the product (several minutes) during drum drying but at a high temperature. These results agree with the observation by Bhatta et al [36] who reported lower retention of total polyphenol content in freeze-dried maple sugar than that of vacuum double-drum-dried sugar.…”

Freeze-Drying of Plant-Based Foods

“…One such nontraditional plant source food is maple syrup. Maple syrup is composed of a mixture of sugars (66% sucrose, 0.4% glucose, and 0.5% fructose), minerals and water, and traces of organic acids, proteins, and polyphenols [66]. Bhatta et al [67] studied the drying of maple syrup to produce a maple sugar powder.…”

The Physicochemical Characterization and In Vitro Digestibility of Maple Sugar Sand and Downgraded Maple Syrups

“…This is lower than the PPAQ averages of 1183 µg/g and a range of 488-2124 µg/g based on the analysis of 135 dark, robust taste syrups. Gallic acid equivalent values may reach 8040 µg/g for very dark maple syrup [31], nearly four times the maximum reported by the PPAQ. Such variations have been attributed to the well-known limitation of the Folin-Ciocalteu assay [44,45], which is an indirect method that can be influenced by non-phenolic compounds (e.g., sugars, organic acids) [46].…”

“…Total polyphenol content was determined using a Folin-Ciocalteu assay [30], modified for use in 96-well microplates [31] with slight modifications. The first three columns were loaded with 0, 10, 20, 30, 40, 50, 60 or 70 µL of a gallic acid standard (50 µg/mL) and then adjusted accordingly with nanopure water to obtain a total volume of 180 µL.…”