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

Abstract

AbstractThe 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 ApplicationsConsumers 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.