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.     

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     

干装苹果罐头加工工艺

为了优化干装苹果罐头加工工艺和稳定产品质量,采用正交实验法,研究柠檬酸质量浓度、Ca2+质量浓度和D-异抗坏血酸钠质量浓度对干装苹果罐头感官品质和色泽的影响,优化固化护色剂的配方;并对新工艺和传统工艺加工的干装苹果罐头的杀菌效果进行了比较。结果表明:固化护色剂的优化配方为25 g/L柠檬酸+2.8 g/L CaCl2+3 g/L D-异抗坏血酸钠。采用新工艺使干装苹果罐头的杀菌公式优化为"5'-25'-30'杀菌温度98℃",杀菌时间缩短16.7%,新工艺生产的干装苹果罐头质量明显优于传统工艺生产的干装苹果罐头。     

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     

1-甲基环丙烯对李果实采后衰老期间非挥发性风味物质影响的多变量分析

采用多变量分析的方法研究1-甲基环丙烯(1-MCP)对‘黑琥珀’李果实20℃贮藏期间非挥发性风味物质形成的影响。结果表明：李果实中主要的糖酸组分是D-果糖、D-葡萄糖、蔗糖、山梨糖醇和苹果酸,D-果糖在采收时与贮藏前期释放较多,蔗糖在贮藏后期时含量较高;1-MCP处理抑制了蔗糖向D-果糖和D-葡萄糖的转化,延缓了可溶性固形物含量的下降,在贮藏后期,1-MCP处理诱导苹果酸、柠檬酸和L-天冬氨酸含量的降低,而增加了果实的pH值。偏最小二乘回归与通径分析结果表明,感官甜酸比与山梨糖醇、蔗糖呈高度正相关,酸度与苹果酸呈高度正相关,且蔗糖是甜酸比的主效因子,对甜酸比的影响主要是通过对山梨糖醇、D-果糖和苹果酸的间接效应实现的。     

Solid-Phase Extraction and Procedure for Determination of Phenolic Compounds in Maple Syrup

A solid phase extraction procedure was developed for the extraction of phenolic compounds from maple syrup. The list of targeted chemicals contains phenolic acids as well as aldehydes, flavanols and others such as coniferyl alcohol and 5-hydroxymethyl furfural. The procedure consists in passing a small quantity of maple syrup, 1 g diluted in 2 ml deionized water, through an Oasis HLB cartridge of 200 mg. The cleanest extracts were obtained by rinsing the cartridge load with formic acid 2 %/methanol (9:1). The analytes eluted with methanol were passed in an high-performance liquid chromatography (HPLC)-DAD system for analysis. The method performances show good recoveries; excluding gallic acid measured at 49 %, the chemical recoveries ranged from 81 to 119 %. Moreover, the method repeatability is less than 12 % (RSD) relative standard deviation for all chemicals except for epicatechin (20 %). The analysis method was applied for the determination of phenolic compounds in maple syrups from different color classes (Extra Light to Amber). Results show that concentrations of phenolic compounds vary among syrup classes and the greatest concentration was observed for the Amber syrups.     

Effects of Maturity, Skin Contact and Carbonation on the Quality of Sterile-Filtered White Muscadine Grape Juice

The effects of grape maturity, skin contact and carbonation on the quality of sterile-filtered muscadine grape juice were investigated. A sensory panel preferred the late maturity juices that had a higher degree of muscadine character and lower total phenolics. Tartaric and malic acid levels decreased with increasing maturity, with malic decreasing to a greater extent. A 24 hr skin contact. at 2°C had no significant effect on sensory results, but increased color intensity, phenolic and organic acid levels as compared to immediate pressing. Carbonated juices were lighter in color and were preferred equally to non-carbonated juices. Juice obtained from a hard pressing regime had slightly higher levels of organic acids than free run juice at the early harvest only.     

The Effect of Calcium Ions on the Hydrolysis of Starch

The ability of raw and dioxan extracted maize and potato starches to bind calcium is shown to influence the in vitro digestibility of the starches using pancreatic α-amylase. The in vitro digestibility of commercial and fractionated glucose syrups in the presence of calcium is also described. Whilst the extraction process improves the digestibility of both maize and potato starches the addition of calcium lowers the digestibility of raw maize starch. Both raw and extracted potato starch digestibility are increased by the addition of calcium however. When raw and extracted maize and potato starches are converted to glucose syrups by an acid hydrolysis no differences are found in the reducing capacities of the syrup produced.     

Malolactic fermentation in sea buckthorn (Hippophaë rhamnoides L.) juice processing

Malolactic fermentation (MLF) traditionally used in winemaking was applied to sea buckthorn to reduce the high sourness of the berry juice. Chemical and microbiological aspects, as well as sensory properties of the juice during MLF were studied in order to develop an optimal process. In 1:1 water diluted juice with malic acid content of 15 g/l and pH 2.8, efficient conversion of l-malic acid to l-lactic acid was achieved with direct inoculation of unadapted Oenococcus oeni at a cell density of 10⁹ CFU/ml. The rapid malic acid degradation was performed by non-growing bacterial cells without loss of sugars, vitamin C, or pulp oil. More than 50% of the initial malic acid was metabolized to lactic acid and CO₂ already in 12 h of fermentation and a significant decrease in sourness and astringency was noticed. In 24 h fermentation, pH value was increased to 3.1 and only 3 g/l malic acid remained in the juice. Prolonged fermentation had only minor effect on malolactic reaction, but off-flavor of the juice began to increase.     

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%。     

Functional Properties of Hydrolyzed Whey Permeate Syrups in Bread Formulations

Hydrolyzed whey permeate syrups (HWPS) prepared by various treatments were incorporated at 6% flour basis as a substitute for sucrose in a typical white pan bread formulation. Results indicated that there were little significant differences in the yeast fermentation rate, proof time, and bread quality among doughs formulated with sucrose (control) and HWPS. Demineralized 75% HWPS produced good functional qualities of dough and yielded bread equal to or better than the control. The 50% and 95% HWPS had some adverse effects on the handling characteristics of the doughs. Breads made with demineralized 50% and 95% HWPS were firmer than the control. The 50% HWPS breads showed darker crust colors, whether HWPS was or was not demineralized.     

Effect of invert sugar on the drying kinetics and water mobility of osmosed‐air dried cantaloupe

Effect of partially replacing sucrose with invert sugar on drying kinetics of osmosed cantaloupe was evaluated using four levels of invert sugar (0, 5, 10 and 15% (v/v)) to partially replace sucrose syrup at 50 °Brix. The osmosed samples were then dried at 60 °C. The osmosed cantaloupe without invert sugar exhibited the fastest drying rate. The drying rate decreased with increasing amounts of invert sugar. An increase in the degree of water binding to invert sugar is the most likely explanation for this effect and is supported by the observed decrease in the NMR relaxation time. The use of invert sugar could reduce water activity of final product but not significantly improve overall appearance. Six different mathematical models were tested for their goodness of fit with experimental data. Modified Henderson and Pabis model was found to give the best fit and was able to predict the drying time accurately.     

Effect of Oxygen, Carbon Dioxide, and Nitrogen on Maple Syrup Stored in Plastic Jugs

Six maple syrups were stored in the dark for 6 months in pigmented and unpigmented high-density polyethylene jugs at room temperature (72°F) in three gas environments-nitrogen, oxygen, and carbon dioxide. The syrup was analyzed for changes in flavor, color, and pH. A taste panel, tasting syrup from pigmented jugs only, detected flavor change in both the oxygen and carbon dioxide environments. There were statistically significant interactions for changes in both color and pH between gas and syrup treatments. The greatest darkening of color and decrease in pH were associated with the carbon dioxide. Jug pigmentation had no detectable effect on the syrup.     

Metabolism of SO₂ binding compounds by Oenococcus oeni during and after malolactic fermentation in white wine

Sulfur dioxide SO? is the key additive for the preservation of wines. Carbonyl and keto compounds in wine can bind to SO? and decrease its efficacy, resulting in higher total SO? requirements. Increased consumer demand for low sulfite and organic wines pose production challenges if SO? binders have not been properly managed during vinification. Malolactic fermentation (MLF) has been known to reduce bound SO? levels but detailed time course studies are not available. In this work, the kinetics of major SO? binding compounds and malic acid were followed during MLF in wine with 12 commercially available strains of Oenococcus oeni. Pyruvic acid, acetaldehyde and α-ketoglutaric acid were degraded to various degrees by O. oeni, but galacturonic acid was not. At the time of malic acid depletion, percent degradation of pyruvate, α-ketoglutaric acid and acetaldehyde was 49%, 14% and 30%, respectively. During MLF, the decrease in average bound SO? levels, as calculated from carbonyl metabolism, was 22%. The largest reduction in wine carbonyl content occurred in the week after completion of MLF and was 53% (107 mg/L to 34 mg/L) calculated as bound SO?. Prolonged activity of bacteria in the wines (up to 3 weeks post malic acid depletion) resulted only in reduced additional reductions in bound SO? levels. The results suggest that microbiological wine stabilization one week after malic acid depletion is an effective strategy for maximum removal of SO? binders while reducing the risk of possible post-ML spoilage by O. oeni leading to the production acetic acid and biogenic amines.     

Berry sensory attributes correlate with compositional changes under different viticultural management of Semillon (Vitis vinifera L.)

A study was performed on Vitis vinifera L. (cv. Semillon) to determine changes in berry sensory attributes and composition when vineyard management practices; leaf removal and bunch thinning are applied. Leaf removal increased skin and pulp acidity sensory attributes which corresponded to a decrease in juice pH, malic acid and potassium. Pulp grassiness also decreased with leaf removal, whereas, skin and pulp grape and citrus flavour intensity increased. Bunch thinning increased pH, malic acid and potassium but this was not related to significant changes in berry sensory attributes; however pulp grassiness flavour did increase. Inductively coupled plasma optical emission also revealed changes in elemental juice levels under different management practices. PCA analysis revealed strong correlations between sensory attributes and berry composition. Grape quality can be manipulated by management practices and berry composition and berry sensory analysis combined may be a useful tool for making management and harvest decisions to achieve certain wine styles.     

Analysis of volatile components and the sensory characteristics of irradiated raw pork

Longissimus dorsi muscle strips, approximately 20 mm long, 40 mm wide, and 5 mm thick (4 g), of pig were randomly placed in a single layer into labeled bags (four strips per bag) and packaged either aerobically or under vacuum. Samples in the bags were irradiated at 0, 5, or 10 kGy and stored at 4°C for 5 days. Lipid oxidation, the amount and identity of volatile components and sensory characteristics of raw pork strips were determined at 0 and 5 days of storage. Irradiated muscle strips produced more 2-thiobarbituric acid reactive substances (TBARS) than nonirradiated only in aerobic packaging during storage. Irradiation had no effect on the production of volatiles related to lipid oxidation, but produced a few sulfur-containing compounds not found in nonirradiated meat. This indicates that the major contributor of off-odor in irradiated meat is not lipid oxidation, but radiolytic breakdown of sulfur-containing amino acids. Many of the irradiation-dependent volatiles reduced to 50 to 25% levels during the 5-days storage under aerobic conditions. Irradiated muscle strips produced stronger irradiation odor than nonirradiated, but no irradiation dose or storage effect was found. Irradiation had no negative effect on the acceptance of meat, and approximately 70% of sensory panels characterized irradiation odor as barbecued-corn-like odor.     

Replacement of Carbon-refined Corn Syrups with Ion-exchanged Corn Syrups in Ice Cream Formulations

Ice cream was manufactured utilizing ten corn syrups at 5% (dry basis) in the mix, 30 DE, 42 DE, 42 DE high maltose (HM), 55 DE HM and 64 DE, each of which was processed through the carbon-refined and ion-exchanged processes. An increase in DE of the syrup led to a decrease in mix viscosity, a decrease in the freezing point of the mix, a decrease in fat destabilization and a decrease in firmness of the ice cream. The ion-exchanged syrups decreased the mix viscosity and produced a drier ice cream with greater fat destabilization but had no influence on mix freezing point depression, overrun, firmness or meltdown. Sensory results from the 42DE HM and 55DE HM carbon-refined and ion-exchanged products evaluated in this study showed no differences in sweetness or texture. The flavor and acceptability of 42DE HM carbon-refined syrup in ice cream was preferred less than the 42DE HM or 55DE HM ion-exchanged syrups.     

Voltage spike and electroconvective vortices generation during electrodialysis under pulsed electric field: Impact on demineralization process efficiency and energy consumption

Electrodialysis (ED) with pulsed electric field (PEF) has never been tested on complex food system such as sweet whey. In this study, seven PEF pulse-pause combinations were compared with DC current to assess their impacts on whey demineralization. High-frequency PEF improved the demineralization rate by 81% while reducing the energy consumption by about 16%. This was explained by the emergence of electroconvective vortices (ECV) at the beginning of each pulse due to the appearance of a voltage spike. Since their lifetime are around 0.5 s, these ECV did not have time to fade off during the whole process in the case of high-frequency PEFs increasing consequently the mass transfer. Furthermore, PEF ratio of 1 decreased pH changes and thus could prevent scaling and organic fouling formation. Hence, ED with PEF is a new advantageous energy-efficient approach for the demineralization of whey that could be used in the dairy industries.Industrial relevanceThis study highlights the beneficial effects of using pulsed electric field (PEF) during ED in comparison to the DC current condition currently used everywhere in industry. First, for the same demineralization rate of sweet whey, PEF requires 16% less energy. This could allow the industries to better deal with the regulatory issues arising from the sustainable development goals. In addition, the use of PEF also prevents the fouling and scaling formation on the membrane, and thus could decrease the load of cleaning agent and the cleaning time required per amount of processed whey. High-frequency PEF such as 0.1 s-0.1 s is a promising greener alternative to conventional ED for demineralization of the million tons of whey generated by the cheese industry every year.