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     

Limitations in the use of ozone to disinfect maple sap

The sap of the maple sugar tree (Acer saccharum) contains 2 to 3% sucrose and is traditionally collected early in the year and concentrated by boiling to produce maple syrup. High levels of microorganisms in the sap occur during holding, leading to a darker syrup with lower economic value. We investigated the use of dissolved ozone as a method to reduce the microbial population in sap. After 40 min of ozone treatment, concentrations of up to 0.30 mg/liter were achieved but were ineffective in reducing the aerobic plate count. Three predominant colonies on nutrient agar were selected for isolation and identification from sap. These included one mucoid and one nonmucoid yeast, both identified as Candida, and Pseudomonas fluorescens. When suspended in buffer, each was readily inactivated by ozone. Addition of 3% sucrose to the buffer markedly reduced the effectiveness of ozone. With the use of an ozone generator with a larger ozone output, saturating ozone concentrations (1 mg/liter) were achieved within 5 min but were accompanied by only a 1-log reduction in aerobic plate count of maple sap. After 40 min of ozone treatment, a less than 3-log reduction occurred. The results indicate that, because of the presence of sucrose, ozone may be of limited use in reducing the microbial population in sap.     

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.     

Correlation of maple sap composition with bacterial and fungal communities determined by multiplex automated ribosomal intergenic spacer analysis (MARISA)

During collection, maple sap is contaminated by bacteria and fungi that subsequently colonize the tubing system. The bacterial microbiota has been more characterized than the fungal microbiota, but the impact of both components on maple sap quality remains unclear. This study focused on identifying bacterial and fungal members of maple sap and correlating microbiota composition with maple sap properties. A multiplex automated ribosomal intergenic spacer analysis (MARISA) method was developed to presumptively identify bacterial and fungal members of maple sap samples collected from 19 production sites during the tapping period. Results indicate that the fungal community of maple sap is mainly composed of yeast related to Mrakia sp., Mrakiella sp., Guehomyces pullulans, Cryptococcus victoriae and Williopsis saturnus. Mrakia, Mrakiella and Guehomyces peaks were identified in samples of all production sites and can be considered dominant and stable members of the fungal microbiota of maple sap. A multivariate analysis based on MARISA profiles and maple sap chemical composition data showed correlations between Candida sake, Janthinobacterium lividum, Williopsis sp., Leuconostoc mesenteroides, Mrakia sp., Rhodococcus sp., Pseudomonas tolaasii, G. pullulans and maple sap composition at different flow periods. This study provides new insights on the relationship between microbial community and maple sap quality.     

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.     

Rapid Prediction of Maple Syrup Grade and Sensory Quality by Estimation of Microbial Quality of Maple Sap Using ATP Bioluminescence

ABSTRACT: ATP bioluminescence was evaluated as a method for assessing the level of microbial contamination in sap and predicting maple syrup characteristics. This approach provided results that were strongly correlated with the standard plate count and took less time than the modified resazurin technique. ATP bioluminescence measurement of sap proved to be reliable for predicting physicochemical and sensory characteristics as indicated by the color and flavor of maple syrup. Most of the syrups made from saps with higher ATP bioluminescence values were darker in color and presented off-flavors. Based on these results, ATP bioluminescence could be used to improve sanitary practices associated with collecting and storing maple sap.     

Maple Syrup as Carbohydrate Source in Dry Sausage Fermentation

Maple syrup was substituted for the glucose-sucrose component of a standard dry sausage formulation to assess its feasibility in fermented meat product manufacture. Sausage batters containing either type carbohydrate were inoculated with a mixed starter culture containing Lactobacillus plantarum, Pediococcus acidilactici and Micrococcus varians. Similar acidification patterns were observed in fermenting batters containing glucose-sucrose mixtures or maple syrup, and processing yields were unaffected by carbohydrate type. However, instrumental texture measurements (shear and compression forces) revealed that sausage made with maple syrup was significantly firmer than the standard product (P≤0.05). Maple syrup could be used in the manufacture of novel fermented meat products.     

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.     

Compositions of maple sap microflora and collection system biofilms evaluated by scanning electron microscopy and denaturing gradient gel electrophoresis

The bacterial microflora of maple sap and biofilms in collection system tubing were studied through the use of bacterial counts, scanning electron microscopy (SEM) of surfaces and the analysis of 16S rRNA gene by denaturing gradient gel electrophoresis (DGGE). Samples were taken at five times during the 2002 and 2003 seasons in order to follow the changes in the microflora of this complex ecosystem. Bacterial counts showed the growth of bacterial populations as the season advanced. These populations were mainly composed of psychrotrophic bacteria and Pseudomonas spp. SEM results confirmed the suspected presence of biofilms on the inner surfaces of tubing samples. Bacterial colonization and biofilm formation progressively increased during the season for both lateral and main line surfaces, and biofilms were mainly composed of rod shape bacteria. The bacterial microflora profiles obtained for sap and corresponding biofilm by DGGE showed up to 12 major bands. The Shannon-Weaver index of diversity (H) calculated from DGGE bands were statistically higher for sap samples compared to biofilm. The diversity index was relatively stable or increasing for lateral line sap and biofilm samples during the season while the diversity index for sap and biofilm samples of the main line showed a decreasing profile as the season progressed. Sequence analysis of major DGGE bands revealed the predominance of bacteria from the genera Pseudomonas, Rahnella and another, unidentified genus. The results describe the composition of sap collection system microflora as well as the formation of biofilms and will be useful for further studies on factors affecting maple product quality.     

Trace Components of the Flavor Fraction of Maple Syrup

SUMMARY– An exhaustive chloroform extraction of maple syrup removed the maple flavorants. The extract was analyzed in part by a gas chromatograph-mass spectrometer tandem procedure. Several previously undetected flavor-related compounds were found in trace amounts. Among these were the aromatic compounds acetovanillone, guaiacyl acetone and vanilloyl methyl ketone. These aromatics could have resulted from the ethanolysis of ligneous material previously reported in maple sap. Sugar degradation products found were furfural, hydroxymethylfurfural, lactic acid and levulinic acid. These indicate that the products of caramelization also are part of the maple flavorants.
Acids found, in addition to those above, were the C₅ to C₉ aliphatic acids and oxalic, fumaric and malic acids. All of the acid occurred as ethyl esters resulting from unintentional esterification during extraction. The C, to C, acids may be artifacts perhaps derived from the vegetable oil used as antifoaming agent in syrup processing.     

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.     

Comparison of FTIR, FT-Raman, and NIR Spectroscopy in a Maple Syrup Adulteration Study

ABSTRACT: Maple syrup is prone to adulteration with cheaper sugars, such as corn syrup, due to its simplicity in chemical composition. The adulterated samples were characterized by Fourier Transform infrared (FTIR) spectroscopy in the region of 400 to 4000 cm_-1. Other techniques used for detection and in characterization of samples were the near infrared (NIR; 600 to 1700nm) and Fourier Transform-Raman (FT-Raman; 400 to 4000cm_-1) spectroscopy. Quantifying and classifying adulterants using chemometrics shows that all spectroscopic methods adopted were efficient, but FTIR and FT-Raman were superior to NIR in quantitative characterization of adulterants in maple syrup.     

Assessment of the microbial diversity during an industrial‐scale malting process by a polymerase chain reaction‐denaturing gradient gel electrophoresis analysis

Assessing the microbial diversity during malting is an essential step towards process management and optimization. However, microbial characterization of the malting process has mostly been performed using culture‐dependent methods, which has probably led to biased microbial diversity estimates. The aim of this study was to characterize the bacterial communities during an industrial‐scale malting process using polymerase chain reaction–denaturing gradient gel electrophoresis. The main bacterial strains in the malting process were identified as Sphingomonas spp., Enterobacter spp., Neisseria spp., Escherichia spp., Rhodocyclus spp., Erwinia spp. and Klebsiella spp. according to the GenBank database. The results revealed that the bacterial community structure changed during the malting process, and that the diverse microbial community played an active role in the malting ecosystem. Moreover, the dominant species changed with the aeration conditions during malting, and there was a tendency for aerobic bacteria to gradually become the predominant community during malting. An improved understanding of the complex microbial community during malting enables greater process management control and the production of high‐quality malt. Copyright © 2016 The Institute of Brewing & Distilling     

Partial demineralization of maple sap by electrodialysis: impact on syrup sensory and physicochemical characteristics

In this project, samples of osmosed maple saps were demineralized to 12.5 and 25% levels by electrodialysis (ED). The effect of this treatment on the composition and the physicochemical and sensory properties of maple syrups obtained from demineralized maple sap was evaluated. The ED technology was efficient to decrease levels of malic acid and calcium in osmosed maple saps. Effectively, 38% and 24% decreases in malic acid and calcium respectively were reached for ED with a demineralization level of 25% without any changes in the other measured components of osmosed maple saps. The demineralization process had no effect on the yield of syrups produced and on their characteristics: no significant difference was observed during sensory analysis and viscosity. Moreover, the percentage of light transmission of syrups produced from demineralized osmosed saps was higher than for the control. This work suggests that ED could be a potential technology to decrease or avoid sugar sand formation during maple syrup production. Copyright © 2007 Society of Chemical Industry     

不同加工环境自然发酵羊肉香肠细菌多样性与挥发性风味物质关联分析

为了探究不同加工环境下羊肉香肠理化性质和风味品质的差异,该研究运用高通量测序技术和代谢组学技术对四川省成都市、乐山市和安徽省安庆市手工制作自然发酵羊肉香肠的常规理化特性、细菌多样性和挥发性风味物质对比分析。结果表明,安庆样品中微生物的丰富度水平和物种多样性水平最高;三个加工环境样品中葡萄球菌属、环丝菌属、Lachnospiraceae_NK4A136_group属、拟杆菌属、Odoribacter属、乳酸杆菌属等相对丰度较高;成都样品的差异物种为葡萄球菌属,乐山样品的差异物种为环丝菌属,安庆样品的差异物种为Lachnospiraceae_NK4A136_group属与一个无法鉴定的菌属。成都和乐山样品的挥发性风味物质组成相似,以醛类物质为主,安庆样品则存在一定差异,以酯类物质为主。羊肉发酵香肠中优势菌群与关键挥发性风味物质存在显著的正相关性,表明优势微生物种类决定了关键挥发性风味物质种类。研究结果为阐明不同加工环境下羊肉香肠的细菌菌群结构及挥发性风味特征提供数据支持,为从加工环境角度揭示传统发酵香肠优势菌群对关键挥发性风味的影响提供了科学依据。     

TALOSURF界面活性剂在糖厂低纯度物料中的应用研究

在糖厂生产过程中 ,当糖浆的纯度低于 80 AP时 ,糖膏粘度增加 ,煮制、分蜜困难 ,影响生产的均衡性 ,生产能力下降 ,产品质量无法保证。这个问题在糖厂榨季前后甘蔗品质不高及甘蔗欠新鲜时都发生 ,为了解决这一棘手问题 ,我们使用 TAL OSURF界面活性剂进行了全面的应用研究。研究表明 ,TAL OSURF界面活性剂对处理低纯度物料有着明显的效果 ,提糖率及产品质量均有所提高。     

气调包装对烤鸭腿货架期及微生物多样性的影响

为延长烤鸭腿货架期、保持其食用品质并阐明烤鸭腿冷藏过程中的菌群演替规律,本实验以托盘包装为对照组,研究了0～4 ℃条件下两种气调包装（100%（体积分数,下同）N2、50% CO2＋50% N2）对烤鸭腿贮藏过程中微生物（菌落总数、乳酸菌数、肠杆菌科数）、硫代巴比妥酸反应产物值及感官特性的影响,并通过高通量测序分析了贮藏过程中烤鸭腿的微生物多样性。结果表明：与托盘包装和100% N2包装相比,50% CO2＋50% N2包装显著抑制了烤鸭腿微生物的生长（P＜0.05）,使其货架期接近21 d,并抑制了其脂肪氧化（P＜0.05）,较好地维持了烤鸭腿的品质和感官特性。贮藏时间和包装方式对贮藏后期烤鸭腿的菌群结构有明显影响,泛菌属、类香味菌属、假单胞菌属和不动杆菌属为50% CO2＋50% N2包装烤鸭腿中的优势菌群,索丝菌属、泛菌属、假单胞菌属、肉食杆菌属和明串珠菌属为100% N2包装烤鸭腿中的优势菌群,优势菌群的不同是导致不同包装方式烤鸭腿间货架期产生差异的主要原因。     

Microbiological stabilization of Aloe vera (Aloe barbadensis Miller) gel by high hydrostatic pressure treatment

The effect of high hydrostatic pressure (HHP) treatment (300, 400 and 500MPa for 1 and 3min at 20°C) on the microbiological shelf-life and microbiota composition of Aloe vera gel during 90days of storage at 4°C was investigated. Aerobic mesophilic and psychrotrophic bacteria, as well as moulds and yeasts, were enumerated after HHP treatment and through cold storage. Randomly selected isolates from the count plates were identified by standard methods and the API identification system. Results showed that HHP treatment at or over 400MPa for 3min were effective to keep the microbial counts to undetectable levels during the whole storage period, and consequently the microbiological shelf-life of A. vera gel was extended for more than 90days at 4°C. The microbiota in the untreated A. vera gel was dominated by Gram-negative bacteria (mostly Rahnella aquatilis) and yeasts (mostly Rhodotorula mucilaginosa). In contrast, Gram-positive bacteria tentatively identified as Arthrobacter spp. and Micrococcus/Kocuria spp. were the predominant microorganisms in samples pressurized at 300MPa for 1 and 3min, while Bacillus megaterium predominating in samples treated at 400MPa for 1min. At 400MPa for 3min and above, the microbial growth was completely suppressed during at least 90days; however, viable spore-formers were detected by enrichment.