Maple sap predominant microbial contaminants are correlated with the physicochemical and sensorial properties of maple syrup

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

The maple syrup industry generates substandard syrups and sugar sand as by-products, which are underused. In this study, we conducted a comprehensive analysis of the physicochemical composition of these products to assess their potential for valorization. Using HPLC analysis, we measured sugar and organic acid content as well as total polyphenol content using the Folin-Ciocalteu method. Additionally, we evaluated the in vitro digestibility using the TIM-1 model. We showed that the composition of ropy and buddy downgraded syrups is comparable to that of standard maple syrup, whereas sugar sand's composition is highly variable, with carbohydrate content ranging from 5.01 mg/g to 652.89 mg/g and polyphenol content ranging from 11.30 µg/g to 120.95 µg/g. In vitro bioaccessibility reached 70% of total sugars for all by-products. Organic acid bioaccessibility from sugar sand and syrup reached 76% and 109% relative to standard maple syrup, respectively. Polyphenol bioaccessibility exceeded 100% during digestion. This can be attributed to favorable extraction conditions, the breakdown of complex polyphenol forms and the food matrix. In conclusion, our study demonstrates that sugar sand and downgraded maple syrups exhibit digestibility comparable to that of standard maple syrup. Consequently, they hold potential as a source of polyphenols, sugar or organic acids for applications such as industrial fermentation or livestock feeds.

Maple Syrup: Chemical Analysis and Nutritional Profile, Health Impacts, Safety and Quality Control, and Food Industry Applications

Maple syrup is a delicacy prepared by boiling the sap taken from numerous Acer species, primarily sugar maple trees. Compared to other natural sweeteners, maple syrup is believed to be preferable to refined sugar for its high concentration of phenolic compounds and mineral content. The presence of organic acids (malic acid), amino acids and relevant amounts of minerals, such as potassium, calcium, zinc and manganese, make maple syrup unique. Given the growing demand for naturally derived sweeteners over the past decade, this review paper deals with and discusses in detail the most important aspects of chemical maple syrup analyses, with a particular emphasis on the advantages and disadvantages of the different analytical approaches. A successful utilization on the application of maple syrup in the food industry, will rely on a better understanding of its safety, quality control, nutritional profile, and health impacts, including its sustainability issues.

Color Index of Transformer Oil: A Low-Cost Measurement Approach Using Ultraviolet-Blue Laser

The color of transformer oil can be one of the first indicators determining the quality of the transformer oil and the condition of the power transformer. The current method of determining the color index (CI) of transformer oil utilizes a color comparator based on the American Society for Testing and Materials (ASTM) D1500 standard, which requires a human observer, leading to human error and a limited number of samples tested per day. This paper reports on the utilization of ultra violet-blue laser at 405- and 450-nm wavelengths to measure the CI of transformer oil. In total, 20 transformer oil samples with CI ranging from 0.5 to 7.5 were measured at optical pathlengths of 10 and 1 mm. A linear regression model was developed to determine the color index of the transformer oil. The equation was validated and verified by measuring the output power of a new batch of transformer oil samples. Data obtained from the measurements were able to quantify the CI accurately with root-mean-square errors (RMSEs) of 0.2229 for 405 nm and 0.4129 for 450 nm. This approach shows the commercialization potential of a low-cost portable device that can be used on-site for the monitoring of power transformers.

The Amber-Colored Liquid: A Review on the Color Standards, Methods of Detection, Issues and Recommendations

For most natural or naturally-derived liquid products, their color reflects on their quality and occasionally affects customer preferences. To date, there are a few subjective and objective methods for color measurement which are currently utilized by various industries. Researchers are also improving these methods and inventing new methods, as color is proven to have the ability to provide various information on the condition and quality of the liquid. However, a review on the methods, especially for amber-colored liquid, has not been conducted yet. This paper presents a comprehensive review on the subjective and objective methods for color measurement of amber-colored liquids. The pros and cons of the measurement methods, the effects of the color on customer preferences, and the international industry standards on color measurements are reviewed and discussed. In addition, this study elaborates on the issues and challenges related to the color measurement techniques as well as recommendations for future research. This review demonstrates that the existing color measurement technique can determine the color according to the standards and color scales. However, the efforts toward minimizing the complexity of the hardware while maximizing the signal processing through advanced computation are still lacking. Therefore, through this critical review, this review can hopefully intensify the efforts toward finding an optimized method or technique for color measurement of liquids and thus expedite the development of a portable device that can measure color accurately.

Chemistry, processing, and functionality of maple food products: An updated comprehensive review

Maple sap is a rich nutrient matrix collected from Acer trees to produce several food products (i.e., sap, water, extract, syrup, and sugar), of which syrup is the most famous in the food industry for its distinct taste and flavor. Maple syrup is produced from the sap of several species (Acer saccharum, Acer nigrum, and Acer rubrum) of maple. Maple syrup is chiefly produced through the concentration of sap via thermal evaporation (pan evaporation) or membrane separation. Each processing technique affects the quality and characteristics of processed maple products. The chemistry of maple products is dominated by a myriad of other phytoconstituents other than sugar, that is, phenolics, to mediate for its many health benefits. The health-promoting effects of maple products included antioxidant, antimicrobial, antimutagenic, anti-inflammatory, and antiproliferative activities. This review capitalizes on maple food products focusing on their chemistry, processing, and health benefits compared with other sugar sweeteners. The impact of processing on maple syrup composition and biological effects in relation to original maple sap are further presented. PRACTICAL APPLICATIONS: Maple food products are natural sweeteners of significant importance due to their economic, nutritional, and health benefits. Apart from the predominant ingredient sucrose, the chemical composition of maple products comprises phenolics, pyrazines, vitamins, minerals, organic acids, and phytohormones. These bioactive compounds are of potential value owing to their health-promoting benefits, including antioxidant, antiproliferative, and antimutagenic effects. Quebecol, lariciresinol, and secoisolariciresinol are suggested as distinct markers for maple products and not common in other plant-derived syrups. Several factors, including the processing parameters and the phytochemical profile, affect maple products' flavor and color. In addition, microbial contamination of maple sap can also affect maple product quality. Further research on the effect of processing techniques and environmental conditions on the phytochemicals profile and biological effects of maple food products should now follow. Application of other omics tools, that is, genomics, proteomics, and metabolomics, to understand maple syrup effects on the human body can help reveal its exact action mechanisms or points for any potential health hazards for certain ailments.

Innovative Fermented Beverages Made with Red Rice, Barley, and Buckwheat

The increase in food intolerances, allergies, and food-based lifestyle choices has dramatically increased the consumer demand for healthy foods characterized by pleasant sensory traits. In such a context, innovative cereal-based beverages are characterized by high nutritional value, pleasant palatability, and potential healthy properties. In the present study, a pool of 23 lactic acid bacteria strains was preliminary assayed as monocultures for the fermentation of three ad hoc formulated cereal- (red rice and barley) and pseudocereal (buckwheat) -based substrates. Eight strains with the best performance in terms of acidification rate were selected for the formulation of three multiple strain cultures to be further exploited for the manufacture of laboratory-scale prototypes of fermented beverages. The compositional and microbiological features of the three experimental beverages highlighted their high biological value for further exploitation.

Metabolomics reveals chemical changes in Acer saccharum sap over a maple syrup production season

Maple syrup, made by boiling the sap of Acer saccharum, is an important agriculture commodity in eastern Canada and New England. Although the collection season is relatively short, a rich progression in the sensory qualities of maple syrup can occur throughout the season. A risk associated with maple syrup production at the end of a season is the development of off-flavors that result in syrup with little to no commercial value. Maple syrup producers in Canada and the USA call this ‘buddy syrup’. In this study, sugar maple (Acer saccharum) sap was collected in sequential samples through the harvest season from stands across Ontario. Metabolomics analysis of the sap samples was performed by high-resolution mass spectrometry. This revealed an evolution of the chemical composition, mainly occurring 30 days prior to leaf emergence. The major chemical constituent of maple syrup, sucrose, decreased sharply in late season sap, driven by microbial activity. The alditol mannitol increased in late season sap to concentrations ≥2 mg/mL and is likely an indicator of the start of photosynthesis. Amino acids, notably methionine and asparagine were present in higher amounts in late season sap. Non-targeted analysis revealed a series of related compounds that contained quaternary ammonium moieties including choline, hercynine, trigonelline, glycine betaine and carnitine increased in late season sap. These classes of compounds could act as methyl donors during the heating/evaporation of sap into syrup, affecting taste. Based on descriptions of the nature of buddy syrup and an extensive literature on flavors in foods, the amino acids methionine and asparagine were found as likely precursors to the compounds responsible for buddy syrup.

Effects of heater wattage on sap flux density estimates using an improved tree-cut experiment

We assessed the effects of heater wattage on sap flux estimates from heat dissipation sensors and generated calibrated equations for 1-year-old Eucalyptus grandis Hill ex Maiden trees. We used a total of eight trees ranging from 3 to 6 cm in diameter. Our calibration experiment was performed with a modified tree-cut approach, which allowed us to estimate gravimetric water use manually weighing 20 l buckets every 15 min while sap flux was monitored on each tree. Our results indicate that changes the current supplied to the heaters from 0.15 to 0.25 W does not significantly influence sap flux estimates, as long as the maximum temperature (Tmax) is properly determined for each period when wattage is different, and natural temperature gradients are corrected. Using the original parameters developed for this method, sap flux density and sap flow had an average underestimation of 53%, which according to our analysis had a reduced but relevant correlation with tree diameter (R2 = 0.3, linear regression). These results may allow researchers to supply different currents to heat dissipation sensors to increase sensitivity or to reduce power consumption. They also provide evidence in favor of the correction and use of raw data collected when unwanted changes in wattage occur. The relationship observed between estimation error and tree diameter, while not strongly significant, suggests that diameter plays an important role in the estimation errors that has not been previously considered, and requires further research.

A systems biology approach to explore the impact of maple tree dormancy release on sap variation and maple syrup quality

Maple sap is a complex nutrient matrix collected during spring to produce maple syrup. The characteristics of sap change over the production period and its composition directly impacts syrup quality. This variability could in part be attributed to changes in tree metabolism following dormancy release, but little is known about these changes in deciduous trees. Therefore, understanding the variation in sap composition associated with dormancy release could help pinpoint the causes of some defects in maple syrup. In particular, a defect known as "buddy", is an increasing concern for the industry. This off-flavor appears around the time of bud break, hence its name. To investigate sap variation related to bud break and the buddy defect, we monitored sap variation with respect to a dormancy release index (S_bb) and syrup quality. First, we looked at variation in amino acid content during this period. We observed a shift in amino acid relative proportions associated with dormancy release and found that most of them increase rapidly near the point of bud break, correlating with changes in syrup quality. Second, we identified biological processes that respond to variation in maple sap by performing a competition assay using the barcoded Saccharomyces cerevisiae prototroph deletion collection. This untargeted approach revealed that the organic sulfur content may be responsible for the development of the buddy off-flavor, and that dormancy release is necessary for the appearance of the defect, but other factors such as microbial activity may also be contributing.

Analysis of plastic residues in maple sap and syrup collected from tubing systems sanitized with isopropyl alcohol

A plastic tubing system operated under vacuum is usually used to collect sap from maple trees during spring time to produce maple syrup. This system is commonly sanitized with isopropyl alcohol (IPA) to remove microbial contamination colonizing the system during the sugar season. Questions have been raised whether IPA would contribute to the leaching of plastic residues in maple sap and syrup coming from sanitized systems. First, an extraction experiment was performed in the lab on commercial plastic tubing materials that were submitted to IPA under harsh conditions. The results of the GC-MS analysis revealed the presence of many compounds that served has target for further tests. Secondly, tests were done on early and mid-season maple sap and syrup coming from many sugarbushes using IPA or not to determine potential concentrations of plastic residues. Results obtained from sap and syrup samples showed that no quantifiable (< 1–75 μg/L) concentration of any plastic molecules tested was determined in all samples coming from IPA treated or not treated systems. However, some samples of first sap run used as a rinse solution to be discarded before the season start and that were coming from non sanitized or IPA sanitized systems, showed quantifiable concentrations of chemical residue such as ultraviolet protector (octabenzone). These results show that IPA can be safely used to sanitize maple sap collection system in regards to the leaching of plastic residues in maple sap and syrup and reinforced the need to thoroughly rinse the tubing system at the beginning of the season for both sanitized and non sanitized systems.

Identification of the fitness determinants of budding yeast on a natural substrate

The budding yeasts are prime models in genomics and cell biology, but the ecological factors that determine their success in non-human-associated habitats is poorly understood. In North America Saccharomyces yeasts are present on the bark of deciduous trees, where they feed on bark and sap exudates. In the North East, Saccharomyces paradoxus is found on maples, which makes maple sap a natural substrate for this species. We measured growth rates of S. paradoxus natural isolates on maple sap and found variation along a geographical gradient not explained by the inherent variation observed under optimal laboratory conditions. We used a functional genomic screen to reveal the ecologically relevant genes and conditions required for optimal growth in this substrate. We found that the allantoin degradation pathway is required for optimal growth in maple sap, in particular genes necessary for allantoate utilization, which we demonstrate is the major nitrogen source available to yeast in this environment. Growth with allantoin or allantoate as the sole nitrogen source recapitulated the variation in growth rates in maple sap among strains. We also show that two lineages of S. paradoxus display different life-history traits on allantoin and allantoate media, highlighting the ecological relevance of this pathway.