June 2008 No 231A0508E
EVALUATING MAPLE SAP Q U A L I T Y – T H E G L U C O METER
SUMMARY: Luc Lagacé and Carmen Charron The glucometer can be used as a tool for the INTRODUCTION – As the maple sugar apparatus that can be used to set evaluation of maple season advances, maple sap is more quality standards for maple sap. sap quality likely to be contaminated by Originally, the glucometer was It is rapid and easy to microorganisms. A high level of developed to measure the level of use microbial activity in maple sap will glucose in the blood of people It enables the cause the inversion of sucrose suffering from diabetes. In the determination of the glucose level resulting resulting in the accumulation of proposed application, the glucometer from the microbial inverted sugars such as glucose in is used to determine the level of degradation of maple maple sap. Inverted maple sap is glucose in maple sap as well as sap sugars often considered of poor quality since concentrated maple sap in a rapid The level of glucose in maple sap is highly maple syrup made from it is generally and easy way. darker in color and may also present related to the dark This maple syrup fact sheet explains color and burnt sugar taste defects such as burnt sugar how the glucometer can be used to taste of maple syrup taste. To improve the maple syrup verify the level of sugar degradation production practices in regards to by microorganisms in maple sap and syrup quality and commercial value, it I N T H I S concentrated maple sap which are is necessary to monitor and evaluate NUMBER: associated to the decrease in quality the quality of maple sap during the and commercial value of maple course of the production. By doing so, Introduction 1 syrup. production parameters related to the decrease in quality and commercial How to use the 1 glucometer value can be identified and corrections can be applied. Glucometer versus 2 color and flavour The glucometer is one such
Summary Table for 3 threshold values HOW TO USE THE GLUCOMETER – In order to evaluate the level of glucose Glucometer 3 comparisons in maple sap and concentrated maple sap with the glucometer, refer Conclusion 3 to the instructions manual supplied with the instrument. Modify the How to reach us 4 procedures by replacing the blood sampling by maple sap or Figure 1 – Example of a glucometer (One concentrated maple sap (no dilution). touch basic from LifeScan) that can be used for the quality evaluation of maple Glucometers can be obtained in most sap and concentrated maple sap at the pharmacies. sugar house Page 2 NO 231A0508E
RELATION SHIP BETWEEN THE GLUCOSE CONCENTRATION IN MAPLE SAP OR CONCENTRATED MAPLE SAP AND THE COLOR OF MAPLE SYRUP A high level of glucose in maple sap will contribute to non-enzymatic browning reactions (Maillard reaction and caramelization) taking place during the thermal evaporation process used in maple syrup confection. These reactions are responsible for the dark color of maple syrup. According to Figure 2, the glucometer permits the determination of the glucose concentration in maple sap in order to anticipate the final color of the corresponding syrup. By keeping records of glucometer readings of maple sap and color of corresponding syrup, it is possible to determine reading thresholds that will lead to the production of syrups with and acceptable color according to personal preferences. Figure 2A shows an example of the relationship between the glucometer reading of maple sap and the color of corresponding maple syrup. From these results, a glucometer reading at 1 mmol/L in maple sap was defined as a threshold value associated to the production of a higher color grade syrup (grade B or higher, >44% light transmittance). In the same way, Figure 2B shows a threshold value of 3 mmol/L for concentrated maple sap associated to a majority of syrups with a higher color grade (grade B or higher, >44% light transmittance). Table 1 provides a summary of the threshold values determined for the One Touch Basic glucometer for sap and concentrated maple sap. A close monitoring of maple sap or concentrated maple sap using the glucometer during production will help identify proper conditions leading to the Figure 2 – Color of syrup (% T at 560 nm) and corresponding production of maple syrups that meet personal glucometer reading of maple sap (A) et and concentrated maple sap preferences in terms of color and flavour and (B) obtained with the One Touch Basic glucometer . Red horizontal lines at 44%T are used to differentiate higher color grades (grade B encourage the application of good production or higher) and lower color grades (grade C or less) syrups. Red practices. In fact, a great proportion of syrups of higher vertical lines indicate the threshold values for glucometer readings. grades are related to a low glucometer reading. Some Red squares indicate syrups with intense burnt sugar taste. exceptions however are noted where the darker color of syrup would be attributed to other factors (circled points in Fig. 2). «A close monitoring of maple sap or concentrated maple RELATION SHIP BETWEEN THE G L U C O S E CONCENTRATION IN MAPLE sap using the glucometer SAP OR CONCENTRATED MAPLE SAP AND THE INTENSE BURNT along with the corresponding SUGAR TASTE OF MAPLE SYRUP color and flavour of maple syrup, will help identify Non-enzymatic browning reactions related to the increased glucose concentration in glucometer reading thresholds maple sap or concentrated maple sap are also precursors of the burnt sugar taste of leading to the production of maple syrup. Burnt sugar taste (also known as empyreumatic taste) can sometimes be syrups that meet personal considered as a taste defect when the intensity is high. Figure 2 shows that intense burnt preferences in terms of color sugar taste (red squares) is exclusively observed for lower grade syrups (grade C or less) ad flavour and encourage the and that it can also be anticipated by glucometer readings of maple sap or concentrated application of good maple sap. production practices» Page 3 NO 231A0508E
Table 1. – Summary of glucometer reading threshold values obtained with the One Touch Basic glucometer Maple sap Concentrated maple sap 1.0 mmol/L 3.0 mmol/L*
* Value obtained for concentrated maple sap at 10°Brix (mean value). Subject to variation according to °Brix of concentrated maple sap
COMPARED READINGS FO R DIFFERENT GLUCOMETERS
Figure 3 – Relationship between the concentration of added glucose in A) maple sap and B) concentrated maple sap and the glucome ter reading obtained from different glucometers. The vertical red lines indicate the threshold readings determined with the One T ouch Basic glucometer for maple sap and concentrated maple
Many glucometers are available on the market. Data the exact concentration of glucose. These instruments are the presented in Figure 2 and Table 1 are from readings Accu-Chek Aviva glucometer which overestimates the glucose obtained with the One Touch Basic glucometer only. A concentration and the Accu-Chek Compact glucometer which comparative evaluation was however made by obtaining tends to underestimate the concentration of glucose. One Touch readings with different glucometers available on the Basic, Accu-Chek Advantage and Ascencia Contour glucometers market on maple sap (Fig. 3A) and concentrated maple for their part seemed to give a reliable evaluation of the glucose sap (Fig. 3B) added with different concentrations of concentration in maple sap or concentrated maple sap. This glucose. According to Figure 3, glucometer readings may being said, all of these instruments can be used as a quality vary from one instrument to another. It should be noted control tool for maple sap and concentrated maple sap knowing that these instruments were developed to measure the that they will not necessary give the same reading and that some blood glucose concentration and that the measuring will perform better than others especially at low concentration. principles can be different according to the model of With a close monitoring, threshold values could eventually be instrument used. Nevertheless, some instruments seem determined for any of the glucometers tested. to perform better than others when used for measuring CONCLUSION – The evaluation of the effect of different glucose concentration in maple sap or concentrated production variables and the determination of threshold values maple sap. From the data obtained, all instruments for these variables is becoming an important issue for producers offered a good linearity between glucometer readings involved in quality management and optimization at the and concentration of added glucose (R2 > 0.98). Some sugarbush. To do this, maple syrup producers must use reliable instruments however show a better sensitivity. A good instruments. In this respect, the glucometer was found to be reading sensitivity enables a better evaluation of product reliable to evaluate the quality of maple sap and concentrated quality near the threshold limits. Therefore, the One maple sap in a fast, easy and affordable way. This instrument Touch Basic and Accu-chek Aviva glucometers showed enables maple syrup producers to keep track of glucometer the lowest readings and were able to read concentrations readings and determine threshold values. The glucometer in an lower than the threshold value of 1 mmol/L in maple sap. instrument that can help modern maple syrup producers to For the 3 mmol/L threshold value in concentrated maple establish good production practices intended for a real quality sap, all instruments provided reading within this value. control at the sugarbush. For some instruments, readings did not perfectly reflect Page 4 NO 231A0508E
C E N T R E D E Centre ACER Inc. is a non profit organization dedicated entirely to research, RECHERCHE, DE development and technology transfer in the production of maple products. Its DÉVELOPPEMENT ET DE TRANSFET mission is to perform research, development and technology transfer primarily of TECHNOLOGIQUE public interest contributing to the maple industry development and a sustainable use ACÉRICOLE INC. of forest resources; to maintain and develop, in collaboration with the industry representatives, the technical and scientific expertise in maple products; to participate in the promotion and the development of the Quebec maple industry 142 Rang Lainesse through its technological know-how and scientific exchanges. Centre ACER Inc. also St-Norbert d'Arthabaska, acts as a convergence hub for research, development and technology transfer for Québec, Canada. G0P 1B0 maple products.
Phone : 819-369-4000 Fax : 819-369-9589 [email protected]
Our web site www.centreacer.qc.ca