Applying behavioral economics-based approaches to examine the effects of liquid sucrose consumption on motivation

Overconsumption of sugar contributes to obesity in part by changing the activity of brain areas that drive the motivation to seek out and consume food. Sugar-sweetened beverages are the most common source of excess dietary sugar and contribute to weight gain. However, very few studies have assessed the effects of liquid sucrose consumption on motivation. This is due in part to the need for novel approaches to assess motivation in pre-clinical models. To address this, we developed a within-session behavioral economics procedure to assess motivation for liquid sucrose. We first established and validated the procedure: we tested several sucrose concentrations, evaluated sensitivity of the procedure to satiety, and optimized several testing parameters. We then applied this new procedure to determine how intermittent vs. continuous access to liquid sucrose (1 M) in the home cage affects sucrose motivation. We found that intermittent liquid sucrose access results in an escalation of sucrose intake in the home cage, without altering motivation for liquid sucrose during demand testing (1 M or 0.25 M) compared to water-maintained controls. In contrast, continuous home cage access selectively blunted motivation for 1 M sucrose, while motivation for 0.25 M sucrose was similar to intermittent sucrose and control groups. Thus, effects of continuous home cage liquid sucrose access were selective to the familiar sucrose concentration. Finally, effects of sucrose on motivation recovered after removal of liquid sucrose from the diet. These data provide a new approach to examine motivation for liquid sucrose and show that escalation of intake and motivation for sucrose are dissociable processes.

Effects of dry brining, liquid smoking and high-pressure treatment on the physical properties of aquacultured King salmon (Oncorhynchus tshawytscha) during refrigerated storage

BACKGROUND

Aquacultured King salmon (Oncorhynchus tshawytscha) pieces were dry brined with a salt/brown sugar mix, dipped in liquid smoke for 3 min, vacuum packed, high hydrostatic pressure (HHP) treated at 600 or 200 MPa for 5 min and stored at 4 °C for up to 40 days.

RESULTS

The surface redness (average a*) of the samples increased after dry brining, then decreased after liquid smoke treatment. HHP did not change the outside color of liquid-smoked samples. However, the inside color changed depending on pressure. HHP-treated control samples without dry brining and liquid smoking changed to a pale pink color. HHP at 600 MPa resulted in a significant increase in hardness. Compared with fresh samples, dry-brined samples had reduced water activity, while samples dipped in liquid smoke had lower pH values.

CONCLUSION

Dry brining and liquid smoking protect the outside color of salmon against changes caused by HHP. The increase in hardness may counteract the softening of the smoked salmon tissue over time.

Hydrogen sulfide extends the postharvest life and enhances antioxidant activity of kiwifruit during storage

BACKGROUND

Exogenous hydrogen sulfide (H₂S) treatment can prolong the postharvest life of cut flowers and strawberries. Little work has been done to explore the effects of H₂S on respiratory climacteric fruits such as kiwifruits during storage. Therefore the aim of the present study was to evaluate the effects of H₂S treatment at concentrations of 15–1000 µmol L⁻¹ on the postharvest life of kiwifruit during 25 °C storage and the role of H₂S in regulating the antioxidant defensive system of kiwifruit.

RESULTS

Treatments with 45 and 90 µmol L⁻¹ H₂S significantly inhibited the increase in soluble sugar content and the decrease in vitamin C (Vit C), chlorophyll content and firmness, inhibited ethylene production and both superoxide production rate (O(·2)⁻) and hydrogen peroxide content. Kiwifruits with 45 and 90 µmol L⁻¹ H₂S exhibited significantly higher activities of superoxide dismutase, catalase and peroxidase. Treatment with 180 µmol L⁻¹ H₂S promoted the ripening of kiwifruits.

CONCLUSION

Treatments with 45 and 90 µmol L⁻¹ H₂S could delay the maturation and senescence of kiwifruits and maintain higher titratable acid (TA) and Vit C during eating-ripe storage by inhibiting ethylene production, improving protective enzyme activities and decreasing the accumulation of reactive oxygen species to protect the cell membrane during storage.

Differences between easy- and difficult-to-mill chickpea (Cicer arietinum L.) genotypes. Part III: free sugar and non-starch polysaccharide composition

BACKGROUND

Parts I and II of this series of papers identified several associations between the ease of milling and the chemical compositions of different chickpea seed fractions. Non-starch polysaccharides were implicated; hence, this study examines the free sugars and sugar residues.

RESULTS

Difficult milling is associated with: (1) lower glucose and xylose residues (less cellulose and xyloglucans) and more arabinose, rhamnose and uronic acid in the seed coat, suggesting a more flexible seed coat that resists cracking and decortication; (2) a higher content of soluble and insoluble non-starch polysaccharide fractions in the cotyledon periphery, supporting a pectic polysaccharide mechanism comprising arabinogalacturonan, homogalacturonan, rhamnogalalcturonan, and glucuronan backbone structures; (3) higher glucose and mannose residues in the cotyledon periphery, supporting a lectin-mediated mechanism of adhesion; and (4) higher arabinose and glucose residues in the cotyledon periphery, supporting a mechanism involving arabinogalactan-proteins.

CONCLUSION

This series has shown that the chemical composition of chickpea does vary in ways that are consistent with physical explanations of how seed structure and properties relate to milling behaviour. Seed coat strength and flexibility, pectic polysaccharide binding, lectins and arabinogalactan-proteins have been implicated. Increased understanding in these mechanisms will allow breeding programmes to optimise milling performance in new cultivars.

Sugars increase non-heme iron bioavailability in human epithelial intestinal and liver cells

Previous studies have suggested that sugars enhance iron bioavailability, possibly through either chelation or altering the oxidation state of the metal, however, results have been inconclusive. Sugar intake in the last 20 years has increased dramatically, and iron status disorders are significant public health problems worldwide; therefore understanding the nutritional implications of iron-sugar interactions is particularly relevant. In this study we measured the effects of sugars on non-heme iron bioavailability in human intestinal Caco-2 cells and HepG2 hepatoma cells using ferritin formation as a surrogate marker for iron uptake. The effect of sugars on iron oxidation state was examined by measuring ferrous iron formation in different sugar-iron solutions with a ferrozine-based assay. Fructose significantly increased iron-induced ferritin formation in both Caco-2 and HepG2 cells. In addition, high-fructose corn syrup (HFCS-55) increased Caco-2 cell iron-induced ferritin; these effects were negated by the addition of either tannic acid or phytic acid. Fructose combined with FeCl3 increased ferrozine-chelatable ferrous iron levels by approximately 300%. In conclusion, fructose increases iron bioavailability in human intestinal Caco-2 and HepG2 cells. Given the large amount of simple and rapidly digestible sugars in the modern diet their effects on iron bioavailability may have important patho-physiological consequences. Further studies are warranted to characterize these interactions.

Potential of fluorescence spectroscopy for the characterisation of maple syrup flavours

BACKGROUND

Maple syrup has high maket value. It is produced in North East America from the heat-evaporated sap of Acer saccharum Marshall. For marketing purposes, there is interest in defining its flavour profile in a consistent and repeatable manner. An experiment was undertaken to explore the potential of autofluorescence of maple syrup induced at 275 and 360 nm to characterise flavours.

RESULTS

A mixed data factor analysis revealed two independent groups of variables. One represents early season woody and late season empyreumatic flavours. The other is related to off-flavour, confectionery and maple flavours. Maple and confectionery flavours are subtle, difficult to distinguish and opposed to off-flavour. There were clear relationships among the two groups and fluorescence profiles. For each of the five basic flavours, discriminant models based on partial least squares regressions were developed. For each sample of syrup, flavours combined to form flavour profiles, and the results from the five discriminant models were aggregated to reproduce these profiles. For excitation at 275 nm, the woody/off-flavour and confectionery/empyreumatic/maple flavour profiles were classified correctly 86 and 78% of the time (cross-validation) respectively.

CONCLUSION

Induced autofluorescence spectra were shown to contain information related to maple syrup flavours. This fluorescence-flavour relationship is not considered quantitative yet, and further research avenues are proposed.

Encapsulation of thyme (Thymus serpyllum L.) aqueous extract in calcium alginate beads

BACKGROUND

Encapsulation of Thymus serpyllum L. aqueous extract within calcium alginate beads was studied in order to produce dosage formulations containing polyphenolic compounds. Electrostatic extrusion was applied for encapsulation of thyme aqueous extract in alginate gel beads. In addition to hydrogel beads, heat-dried and freeze-dried forms of beads were examined.

METHODS

Encapsulation systems were examined and compared in order to choose the optimal one with respect to entrapment efficiency, preservation of antioxidant activity and thermal behaviour under heating conditions simulating the usual food processing.

RESULTS

The beads obtained with approximately 2 mg g⁻¹ of gallic acid equivalents encapsulated in 0.015 g mL⁻¹ of alginate were spheres of a uniform size of about 730 µm. Encapsulation efficiency varied in the range 50-80% depending on the encapsulation method. Besides, the analysis reveals that the encapsulation process and the material used did not degrade the bioactive compounds, as the total antioxidant content remained unchanged. This was verified by Fourier transform infrared analysis, which proved the absence of chemical interactions between extracted compounds and alginate. Addition of a filler substance, such as sucrose and inulin, in the dried product reduced its collapse and roundness distortion during drying process.

CONCLUSION

This study demonstrates the potential of using hydrogel material for encapsulation of plant poplyphenols to improve their functionality and stability in food products.

Patented techniques for acrylamide mitigation in high-temperature processed foods

Heating foods has many advantages since it adds taste, color, texture and minimizes harmful germs, among others. Flavor and aroma compounds are produced via the Maillard reaction, where various hazardous compounds may form as well, such as acrylamide. Maillard reaction is believed to be the main route for acrylamide formation between reducing sugars (glucose and fructose), sucrose, and the amino acid asparagine, and, consequently, a variety of technologies have been developed to reduce acrylamide concentration in thermally processed foods based either on: (i) Changing process parameters (e.g. time and temperature of cooking) which inhibits Maillard Reaction; (ii) Reducing acrylamide precursor levels in raw materials to be cooked at high temperatures (e.g. by using microorganisms, asparaginase, amino acids and saccharides, blanching, etc.). In this paper, most of the recent patents for acrylamide reduction in foods processed at high temperatures are mentioned and briefly analyzed in order to develop new mitigation techniques for acrylamide in different food matrixes.

Fruit fly bioassay to distinguish "sweet" sugar structures

Palatable response to dietary sugars plays a significant role in influencing metabolic health. New structures are being explored with beneficial health properties, although consumer acceptance relies heavily on desirable sensory properties. Despite the importance of behavioral responses, the ability to elucidate structure-preference relationships of sugars is lacking. A wild population of Drosophila melanogaster was used as a model to perform pairwise comparisons across structural groups to characterize a fruit fly bioassay for assessing sugar preference. Preference was successfully described in structurally relevant terms, particularly through the ability to directly test sugars of related structures in addition to standard sucrose comparisons. The fruit fly bioassay also provided the first report on the relative preference for the β-linked sugar alcohol, gentiobiitol. In making reference to well-known human preferences, the bioassay also raises opportunities for greater understanding of behavioral response to sugar structures in general.

Effect of White Cheese and Sugarless Yoghurt on Dental Plaque Acidogenicity

White cheese and sugarless yoghurt are frequently consumed traditional Turkish foods. The aim of this study was to assess their acidogenic potential when eaten alone or following a rinse with sucrose solution. Plaque pH was measured by a pH microelectrode at baseline to determine the resting plaque pH and at time intervals of 1-60 min after rinsing with 10% sucrose solution or eating the test food for 1 min. White cheese consumption for 1 min increased the plaque pH. When white cheese was eaten 5 min after rinsing with 10% sucrose solution, the plaque pH rose rapidly. After sugarless yoghurt consumption, the pH fell to a similar minimum as for sucrose after 5 min but returned to baseline levels after 30 instead of 60 min. Consumption of sugarless yoghurt after a sucrose rinse initially reduced the plaque pH further but did not affect the time taken for pH to regain baseline levels.

Survey on some contaminants in white sugar from Serbian sugar beet refineries

Refined white sugar is a very pure food product, even though it contains very small amounts of soluble and insoluble impurities. The content of these impurities has nutritional significance and determines the usefulness of sugar for various industrial applications. The main quality criteria used to indicate the content of these impurities are ash and colour. The aim of this paper was to evaluate the quality according to the EU sugar market regime and the content of iron, copper and zinc in white sugar samples from Serbian sugar beet refineries during the 2003 campaign. A total of 166 samples representative of the production of four Serbian sugar refineries were investigated. After wet digestion the concentrations of iron, copper and zinc were determined by flame atomic absorption spectrometry. The mean content of iron, copper and zinc in sugar samples was 0.37 mg/kg, 0.06 mg/kg and 0.02 mg/kg and was significantly different from the average content 0.28 mg/kg, 0.09 mg/kg and 0.07 mg/kg respectively in the analysed European sugar factories. The data were also compared with literature values for commercial white sugar samples from European sugar beet refineries and European legislation set for copper and zinc. Furthermore, the quality of produced sugar was evaluated according to the standards of the European Union indicating that 76% of all investigated Serbian samples belonged to the second sugar quality category.

Resolution of common dietary sugars from probe sugars for test of intestinal permeability using capillary column gas chromatography

BACKGROUND

The most widely accepted method for the evaluation of intestinal barrier integrity is the measurement of the permeation of sugar probes following an oral test dose of sugars. The most-widely used sugar probes are sucrose, lactulose, mannitol and sucralose. Measuring these sugars using a sensitive gas chromatographic (GC) method, we noticed interference on the area of the lactulose and mannitol peaks.

METHODS

We tested different sugars to detect the possible makeup of these interferences and finally detected that the lactose interferes with lactulose peak and fructose interferes with mannitol peak. On further developing of our method, we were able to reasonably separate these peaks using different columns and condition for our assay. Sample preparation was rapid and simple and included adding internal standard sugars, derivitization and silylation. We used two chromatographic methods. In the first method we used Megabore column and had a run time of 34 min. This resulted in partial separation of the peaks. In the second method we used thin capillary column and was able to reasonably separate the lactose and lactulose peaks and the mannitol and fructose peaks with run time of 22 min.

RESULTS

The sugar probes including mannitol, sucrose, lactulose, sucralose, fructose and lactose were detected precisely, without interference. The assay was linear between lactulose concentrations of 0.5 and 40 g/L (r(2)=1.000, P<0.0001) and mannitol concentrations of 0.01 and 40 g/L (r(2)=1.000). The sensitivity of this method remained high using new column and assay condition. The minimum detectable concentration calculated for both methods was 0.5 mg/L for lactulose and 1 mg/L for mannitol.

CONCLUSION

This is the first report of interference of commonly used sugars with test of intestinal permeability. These sugars are found in most of fruits and dairy products and could easily interfere with the result of permeability tests. Our new GC assay of urine sugar probes permits the simultaneous quantitation of sucralose, sucrose, mannitol and lactulose, without interference with lactose and fructose. This assay is a rapid, simple, sensitive and reproducible method to accurately measure intestinal permeability.