Air injection into concentrated maple sap during processing: impact on syrup composition and flavour

BACKGROUND: Air injection (AI) is a relatively new process used during maple sap thermal processing to increase the profitability of maple syrup production by increasing the production of more economically valuable light‐coloured syrup. The effects of applying this technology in conjunction with existing practices employed to increase the efficiency of maple production, such as reverse osmosis (RO), are unknown. The main objective of this work was to investigate the effects of AI on syrup chemical composition and flavour when applied to maple sap concentrated by RO. RESULTS: The chemical composition and flavour of syrup produced simultaneously with and without AI from a common source of maple sap concentrated by RO were compared. The chemical composition of maple syrup produced with AI was within ranges previously published for maple syrup. Syrup produced with AI was significantly lighter in colour than syrup produced without AI from the same sap concentrate (P < 0.001). Although syrup produced with AI contained fewer volatile flavour compounds and had a flavour distinguishable from that of syrup produced without AI from the same concentrated sap, the flavour properties of AI syrup were consistent with those of light‐coloured maple syrup. CONCLUSION: The results indicate that AI can be used in conjunction with RO to effectively increase the economic efficiency of maple syrup production without detrimental impacts on maple syrup properties. Copyright © 2009 Society of Chemical Industry     

Discrimination and classification of adulterants in maple syrup with the use of infrared spectroscopic techniques

Food adulteration is a profit‐making business for some unscrupulous manufacturers. Maple syrup is a soft target of adulterators owing to its simplicity of chemical composition. In this study the use of Fourier transform infrared (FTIR) spectroscopy and near‐infrared (NIR) spectroscopy to detect adulterants such as cane and beet invert syrups as well as cane and beet sugar solutions in maple syrup was investigated. The FTIR spectrum of adulterated samples was characterised and the regions 800–1200 cm^?1 (carbohydrates) and 1200–1800 and 2800–3200 cm^?1 (carbohydrates, carboxylic acids and amino acids) were used for detection. The region between 1100 and 1660 nm in the NIR spectrum was used for analysis. Linear discriminant analysis (LDA) and canonical variate analysis (CVA) were used for discriminant analysis, while partial least squares (PLS) and principal component regression (PCR) were used for quantitative analysis. FTIR was more accurate in predicting adulteration using two different regions (R² > 0.93 and >0.98) compared with NIR (R² > 0.93). Classification and quantification of adulterants in maple syrup show that NIR and FTIR can be used for detecting adulterants such as pure beet and cane sugar solutions, but FTIR was superior to NIR in detecting invert syrups. © 2003 Society of Chemical Industry     

Discrimination and classification of adulterants in maple syrup with the use of infrared spectroscopic techniques

Food adulteration is a profit‐making business for some unscrupulous manufacturers. Maple syrup is a soft target for adulterators owing to its simplicity of chemical composition. The use of infrared spectroscopic techniques such as Fourier transform infrared (FTIR) and near‐infrared (NIR) as a tool to detect adulterants such as cane and beet invert syrups as well as cane and beet sugar solutions in maple syrup was investigated. The FTIR spectra of adulterated samples were characterised and the regions of 800–1200 cm^?1 (carbohydrates) and 1200–1800 and 2800–3200 cm^?1 (carbohydrates, carboxylic acids and amino acids) were used for detection. The NIR spectral region between 1100 and 1660 nm was used for analysis. Linear discriminant analysis (LDA) and canonical variate analysis (CVA) were used for discriminant analysis, while partial least squares (PLS) and principal component regression (PCR) were used for quantitative analysis. FTIR was more accurate in predicting adulteration using the two different regions (R² > 0.93 and 0.98) compared with NIR (R² > 0.93). Classification and quantification of adulterants in maple syrup show that both NIR and FTIR can be used for detecting adulterants such as pure beet and cane sugar solutions, but FTIR was superior to NIR in detecting invert syrups. © 2002 Society of Chemical Industry     

Assessment of maple syrup physico-chemistry and typicity by means of fluorescence spectroscopy

Maple syrup is a natural sweetener obtained from the transformation of maple sap collected mostly from sugar maple (Acer saccharum Marsh) in North America. At present, simple physico-chemical tests are used for routine quality control. Inspectors also taste all batches on the market to ensure authenticity. Because of the presence of various aromatic compounds in sap and syrup, intrinsic fluorescence was tested as a means to characterize the physico-chemistry and typicity of maple syrup. Two hundred samples of sap and their corresponding syrup were obtained from various farms in 2003 and 2004. They were analysed by conventional physico-chemical tests and by fluorescence spectroscopy. Two major regions of fluorescence were found, which were mostly the same for sap and syrup. The first one was at 320 nm, excited at 275 nm, and the second one at 460 nm, excited at 360 (syrup) or 370 nm (sap). The first peak diminishes as harvesting season progresses, while the second peak increases, making it possible to predict the harvesting period of syrup from its spectra (r² = 0.88 in 2003 and 0.81 in 2004). Color of syrup (r² = 0.91 and 0.88) and bacterial counts in sap (r² = 0.75 and 0.78) were also predicted from syrup spectra. Results show that sap spectra are related to syrup spectra and could potentially be used as predictor of quality prior to transformation. Discriminant analysis revealed that between 71% and 95% of syrup samples were correctly classified according to the farm of origin in 2003, and between 78% and 100% in 2004. Proximity was not always a factor of explanation of misclassification, suggesting that precise farm location, rather than the broad region of production is the major factor of typicity.     

电渗析在葡萄糖浆脱盐中的应用

电渗析技术应用于葡萄糖浆的脱盐效果显著。研究表明,脱盐最佳条件为:操作电压30 V,糖浆流量25 L/h,糖浆浓度30%;该条件下,糖浆脱盐率94.69%,糖浆得率77.84%。     

Microbiological, physicochemical and sensory quality of maple syrup aseptically packaged in paper-based laminate

Quality of maple syrup packaged in paper-based laminate at 82°C or room temperature (25°C) was evaluated and compared to a reference syrup packaged in glass bottles stored at 4°C. to prevent microbial growth and blown containers, maple syrup must be heated at 82°C before packaging. Significant pH decrease related to storage temperature was similar to the observation of other authors for glass bottles and cans. Syrup in laminate cartons stored at 4°C, had higher transmittance measurements with time, but at higher storage temperatures, browning effect related to caramelization of sugars balances this transmittance increase. Changes in invert sugar level were significant only in syrup packaged in laminate at 25°C and stored at 23°C and 37°C and were related to the microbial growth. Physicochemical changes were not large enough to affect the overall quality of the product. 'Burnt sugar' off-flavour was detected for samples stored at 37°C. Packaging maple syrup in paper-based laminate at 82°C is an economic alternative to glass bottles, while maintaining a good quality product.     

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

Maple sap processing and microbial contamination are significant aspects that affect maple syrup quality. In this study, two sample sets from 2005 and 2008 were used to assess the maple syrup quality variation and its relationship to microbial populations, with respect to processing, production site and harvesting period. The abundance of maple sap predominant bacteria (Pseudomonas fluorescens group and two subgroups, Rahnella spp., Janthinobacterium spp., Leuconostoc mesenteroides) and yeast (Mrakia spp., Mrakiella spp.,Guehomyces pullulans) was assessed by quantitative PCR. Maple syrup properties were analyzed by physicochemical and sensorial methods. Results indicate that P. fluorescens, Mrakia spp., Mrakiella spp. G. pullulans and Rahnella spp. are stable contaminants of maple sap, as they were found for every production site throughout the flow period. Multiple factor analysis reports a link between the relative abundance of P. fluorescens group and Mrakia spp. in maple sap with maple and vanilla odor as well as flavor of maple syrup. This evidence supports the contribution of these microorganisms or a consortium of predominant microbial contaminants to the characteristic properties of maple syrup.     

Date syrup: Effect of hydrolytic enzymes (pectinase/cellulase) on physico-chemical characteristics, sensory and functional properties

This work is a contribution to give value addition to second grade dates (with hard texture) by the production of enzymatically treated syrup with high commercial value. It was observed that the pulp:water at ratio 1:3 treated with 50 U of pectinase and 5 U of cellulase during 120 min at 50 °C gave the highest recovery of total soluble solids (72.37 g of total soluble solids/100 g fresh basis) and the lower turbidity (186.45 NTU) compared with control without enzyme addition (Total soluble solids yields: 66.34 g of total soluble solids/100 g fresh basis and turbidity: 1513 NTU). physico-chemical measurements indicated that carbohydrates were predominant in all date varieties as well as their syrups (∼69.59-83.76 g/100 g dry matter in dates and ∼62.14-74.68 g/100 g fresh weight in syrup). Allig variety was characterised by a high content of reducing sugars content (∼77.91 g/100 g dry matter), contrary to Deglet Nour (∼23.17 g/100 g dry matter) and Kentichi (∼21.3 g/100 g dry matter).The CIE L∗ a∗ b∗ colour values of the enzyme-treated date syrup of Deglet Nour, Allig and Kentichi variety showed lighter colours (L∗ values ranging from 24.16 to 44) than the control without enzyme (L∗ values ranging from 0.545 to 17.2). Hedonic evaluation showed that enzyme-treated date syrup was more appreciated by consumers. Microbiological study showed that date syrups were free from aerobes, moulds, coliforms and enterobacteriaceae and were microbiologically stable during five months storage. Results suggested that enzymatic treatment could be used for production of date syrup with high commercial value     

Pasteurized and sterilized maple sap as functional beverages: Chemical composition and antioxidant activities

Maple sap has been consumed for centuries as a tonic by the indigenous peoples of eastern North America but is primarily utilized in this region to produce maple syrup. The natural watery form of maple sap makes its application as a functional beverage appealing but due to microbial growth, sterilization or pasteurization would be necessary before sap could be consumed. This study was designed to investigate the chemical composition (sugars, amino acids, organic acids, minerals, and phenolics) and antioxidant effects of maple sap after undergoing pasteurization and sterilization. After both processes, sugars, amino acids, organic acids, and minerals were preserved in the sap samples and they had similar phenolic contents (0.25–0.27 mg/100 g gallic acid equivalents) and antioxidant activities (IC₅₀ ca. 550 μg/mL by DPPH assay). HPLC-DAD analyses revealed over 25 constituents in the sap samples of which 15 were identified using phenolic standards. In addition, one compound, 3′,5′-dimethoxy-4′-hydroxy-(2-hydroxy)acetophenone, not previously reported from maple syrup, was isolated and identified (by NMR) for the first time from maple sap. Therefore, the preservation of chemical constituents and antioxidant activity in maple sap after pasteurization and sterilization warrants its application as a functional beverage beyond its primary use for maple syrup production alone.     

Physicochemical characteristics and sensory optimisation of pineapple leather snack as affected by glucose syrup and pectin concentrations

Effects of glucose syrup (2%, 4%, and 6%) and pectin (0.5%, 1.0%, and 1.5%) concentrations on physicochemical characteristics and sensory acceptability of machine‐formed pineapple leather snack were investigated. Changes in glucose syrup and pectin concentrations significantly affected velocity of forming and total soluble solids content of pineapple paste, but did not affect thickness of pineapple leathers. Increasing pectin concentrations generally increased redness (a*) and yellowness (b*), and hardness (tensile force and work) while decreased moisture content and a_w of pineapple leathers. Two most acceptable pineapple leathers were prepared with 6% glucose syrup and 0.5–1.0% pectin. Increasing pectin concentration from 1.0% to 1.5% negatively affected toughness acceptability, which was attributed to reduced moisture and a_w, and increased tensile force and work. The optimum formulation range consisted of 3.5–6.0% glucose syrup and 0.5–1.0% pectin, yielding products with acceptability scores of 6.7–7.3 (on a 9‐point hedonic scale) for appearance, sourness, sweetness, overall‐taste, toughness and overall‐liking.     

Contribution to the development of a method of maple sap soft drink stabilization by electro-activation technology

Electro-activation (EA) of a maple sap/syrup beverage was studied. The purpose of the study was to assess the product parameters, such as pH, ORP, transmittance and degree Brix, while minimizing energy consumption. The experiments were conducted using three different configurations of the reactor that differed by the position of the anion (AEM) and cation (CEM) exchange membrane relative to the electrodes as well as the nature of the electrolyte (NaCl vs. Na₂CO₃) in the central cell of the reactor. The results showed that the type of configuration, the electric current and the temperature influenced the parameters of the electro-activated beverage. At 23 °C, the beverage was acidified to pH 3.89 with a Redox potential (ORP) of 417.33 mV. At 55 °C and 150 mA, the minimum pH of 3.78 and an ORP of 329.67 mV were obtained. The electric resistance of the electro-activation reactor (EAR) decreased during electro-activation, indicating a gain of energy efficiency corresponding to an electric resistance of 266.76 Ω. Moreover, the reactor configuration and electric current affected the presence or absence of a fouling of the ion exchange membrane at the anodic side. The beverages' transmittance increased slightly during EA without any effect on the degree Brix.     

糖汁电絮凝脱色的研究

研究采用电絮凝法对糖汁进行脱色,考察了电絮凝时间、电流密度、温度、初始pH以及电极间距对糖汁脱色效果的影响。结果表明,用铝做电极材料,电絮凝法处理糖汁的最佳工艺条件为:电絮凝时间12 min、电流密度600 A/m2、温度50℃、电极间距15 mm和初始pH4～9,在此条件下糖汁的脱色率可以达到90%以上。     

糖汁电絮凝提纯的研究

采用电絮凝法对糖汁进行提纯,考察了电絮凝时间、电流密度、温度、电极间距以及初始pH对糖汁提纯效果的影响。结果表明,用铝做电极材料,电絮凝法处理糖汁的最佳工艺条件为:电絮凝时间16min、电流密度700A·m-2、温度50℃、电极间距10mm、初始pH4～9,在此条件下糖汁的简纯度提高率可以达到4.12%。      

氨基酸溶液电渗析脱盐过程的研究

测定了不同浓度和流速下的盐水和氨基酸盐溶液的极限电流密度,分析了浓度、流速、氨基酸含量等因素对电渗析极限电流密度的影响,提出了描述电渗析特性的数学模型。初步研究了应用电渗析对氨基酸盐溶液进行处理时,流速和电压对脱盐率和氨基酸回收率的影响,用较低的流速在接近极限电流密度的条件下操作能达到最好的分离效果。     

Antioxidant,antiradical and antimutagenic activities of phenolic compounds present in maple products

The phenolic compounds in maple sap and syrup were extracted at different periods of the season and were separated to collect the glycosylated compounds and the aglycone compounds. The antioxidant and antiradical activities of each phenolic compound were studied using the thiobarbituric acid reactive substances (TBARS) assay and the N,N-diethyl-p-phenylenediamine (DPD) decoloration test to measure the free radical scavenging. The results showed that in general the phenolic compounds had a good antioxidant and antiradical properties. The glycosylated compounds from maple sap and maple syrup showed a better activity than the aglycones. The antimutagenic effects of each phenolic compounds from maple sap and syrup were also investigated as the inhibition of SOS induction by chemical agents in Salmonella typhimurium TA1535/pSK1002 containing the fusion gene umuC-lacZ. Induction of the SOS gene (umuC) expression was assayed by measuring accumulated β-galactosidase activity using a modified Umu test. The antimutagenic properties were studied per se and after metabolisation by S9 fraction. The results showed that an optimum of antimutagenic properties of the glycosylated metabolites phenolic compounds from sap and syrup was observed at 75% of the season for the sap and at 25% of the season for the syrup. A higher antimutagenic activity was observed at 25% and 100% of the season for aglycones present in syrup and at 75% of the season for aglycones present in sap.     

Growth of soybean sprouts affected by chitosans prepared under various deproteinization and demineralization times

Chitosan, a natural biopolymer derived by deacetylation of chitin, has been extensively used in biomedical, agricultural and food applications. The ultimate aim of research effort was to develop various economic/simplified chitosan production processes for particular food applications. Therefore, a set of experiments was designed to evaluate the effect of chitosans prepared under various deproteinization (DP) times (at 0, 5 and 15 min) and demineralization (DM) times (at 0, 10, 20 and 30 min) on the growth of soybean sprouts. Chitosan treatment increased the total weight of soybean sprouts by 10.7–13.8% compared with that of the control; the effectiveness of the chitosan treatment was independent of DP and DM times. The increase (12.7%) in the growth of soybean sprouts by chitosan prepared without DP and DM steps was noteworthy. This investigation demonstrates that the elimination of DP and DM steps or a reduction in the reaction time required for optimum DP and DM in the production of chitosan needs further studies before being considered for particular usages. Copyright © 2006 Society of Chemical Industry