Simultaneous HPLC Determination of 2,5-Dimethyl-4-hydroxy-3 (2H)-Furanone and Related Flavor Compounds in Strawberries

A rapid methodology (less than 90 min) is described for the qualitative and quantitative analysis of 2,5-dimethyl-4-hydroxy-3 (W)-furanone (furaneol), furaneol-β-glucoside, and 2,5-dimethyl-4-methoxy-3 (2H)-furanone (mesifurane) in strawberries. These compounds were resolved by HPLC with a RP C18 column, using acetate buffer and methanol as binary mobile phase and detection at 280 nm, and confirmed by GC-MS. The aqueous extraction procedure gave an average recovery of these compounds from strawberries > 90%, with detection limits: 0.14 furaneol, 0.05 furaneol-β-glucoside, and 0.36 μg/rnL mesifurane.     

DIRECTION REVERSALS IN THE MECHANICAL SIGNATURE OF CELLULAR SNACKS: A MEASURE OF BRITTLENESS?

The “mechanical signatures” of brittle cellular foods are known to be irregular and irreproducible. Nevertheless, their degree of jaggedness is remarkably similar and can be a measure of such foods' brittleness and perceived crunchiness/crispiness. An irregular curve's “jaggedness” is manifested by frequent direction reversals. Hence, their number can serve as a jaggedness's index. Counting the number of direction reversals in a digitized force‐displacement curve can be done with a simple algorithm, implemented in any general‐purpose software. The number of direction reversals is strongly correlated with the signature's apparent fractal dimension. It is also a reproducible enough parameter to monitor the loss of brittleness in snacks as a result of moisture sorption. This measure of jaggedness, however, is inapplicable to smooth force‐displacement curves because in such records, the small random force fluctuations produced by the digitizing process can create a false impression of “jaggedness.” Although a correction for this artifact can be introduced into the program, its utility is doubtful.     

EXTRACTION OF PROTEINS FROM BUCKWHEAT BRAN

ABSTRACT Proteins from buckwheat bran were extracted by a wet alkaline extraction process, giving a yield of 37.0%of the total nitrogen in the liquid extract, at pH of 6.5. However, the yield could be improved, given a pretreatment of the bran with carbohydrases, thus producing a yield of 56% with cellulase, 58%with pectinase, whereas the increase was minimal with hemicellulase. The maximum yield of 67.5%was obtained by synergistic action of pectinase and hemicellulase, in a pretreatment lasting for 7 h at pH of 3.7.     

ION LEVELS OF FRESH AND PROCESSED SPINACH USING ION CHROMATOGRAPHY

The anion (Cl^?, NO^?₃, So^2-₄, PO^3-₄, OX^2-) and cation (Na⁺, K⁺, NH4⁺) composition of raw, frozen and canned spinach samples was determined by Ion Chromatography (IC). In general, the levels of these ions were determined after typical food processing operations. Important for its health-related and nutritional point of view is the observation that nitrate levels decreased by about 50% with losses of 15% in total organic nitrogen after typical commercial processing methods.     

Evaluation of diffusion coefficients in osmotic concentration of bananas (Musa Cavendish Lambert)

The effect of time of exposure, solution concentration and temperature on the osmotic concentration of banana (slices of 11 mm thickness) was studied in aqueous sucrose solutions. the selectivity of the cellular tissues was reduced by steam blanching the banana slices before osmotic treatment. Effective diffusion coefficients for the loss of water and the increase in sucrose content were determined according to Fick's Law applied to a two-dimensional body; calculated on the basis of the concentration of various components in the liquid phase impenetrating the fruit. These coefficients revealed values similar to binary diffusion coefficients for pure sucrose solutions.     

Measurement of Taste Intensity and Degree of Liking of Beverages by Graphic Scales and Magnitude Estimation

Graphic scaling (GS) and magnitude estimation (ME) of hedonic and intensity responses to 4–30% sucrose in lemonade and 0–16% fat in milk gave similar conclusions about the beverages, but GS was simpler to perform and responses were influenced less by numerical and contextural effects. More restricted ranges were used for ME than for GS, and for hedonic than for intensity responses. Good reproducibility was obtained, except for GS of hedonic responses to lemonade, which were bimodally distributed. Use of a higher sucrose reference (R) in lemonade decreased ME values, and increased the intensity exponent from 0.651 when R was 4% sucrose to 0.973 when R was 10% sucrose. Individual intensity exponents varied from 0.068–0.372 for milk, and from 0.146–1.075 for lemonade when R was 4% sucrose, and from 0.373–2.635 when R was 10% sucrose.     

STARCH MOBILIZATION AND SUCROSE ACCUMULATION IN THE PULP OF KEITT MANGOES DURING POSTHARVEST RIPENING

Sugar is a determinant for the quality of mangoes, but information about its accumulation is scarce. Although starch can contribute to sugar production during ripening, not much is known about the enzymes involved. This work presents the changes in carbohydrate and enzymes during the development and ripening of Keitt mangoes. Starch disappearance was concomitant to a fivefold increase of sucrose, the most abundant sugar of the ripe fruits. The activities of α-amylase, β-amylase, phosphorylase and isoamylase were detected in the pulp, and while α-amylase increased parallel to the starch content, β-amylase presented a 20-fold increase during ripening. On the other hand, high phosphorylase activity was observed when fruits were still accumulating starch, and lowered during ripening. Isoamylase was detected during development and increased slightly during ripening, which would be in agreement to the expected role for isoamylases as acting on both subproduct of starch synthesis and degradation.

PRACTICAL APPLICATIONS

The present work reinforces our previous works that Keitt mangoes do not ripen when attached to the tree. This fact allowed us to study all the starch degradation after mango harvesting which does not occur with the other cultivars. Data obtained in this work reinforce the role of α-amylase, β-amylase and isoamylase rather than the starch phosphorylases on starch granule degradation in mangoes, and the subsequent soluble sugar accumulation.     

Consumer acceptability and purchase intent of probiotic yoghurt with added glucose oxidase using sensometrics,artificial neural networks and logistic regression

This research aimed to identify the drivers of acceptance and purchase intent of a probiotic (Bifidobacterium longum BL05) nonflavoured yoghurt supplemented with glucose oxidase, and to model the consumers’ acceptability using sensometrics and artificial neural networks (ANN). Consumers (n = 100) evaluated the degree of liking of yoghurt assays in respect of appearance, aroma, taste, texture and overall linking. Sensometric techniques – multiple linear regression (MLR), partial least squares regression (PLS), principal component regression (PCR) – and ANN were used to model the overall liking. Sensory drivers of global acceptance and purchase intent were also determined using logistic regression (LR). Hierarchical cluster analysis (HCA) identified three consumer segments that presented differences in all sensory attributes evaluated (P < 0.05). The ANN model showed the best performance to predict overall liking, followed by the MLR, PLS and PCR, indicating that taste and texture were the most significant attributes impacting the yoghurts overall liking. In accordance with the logistic models, overall acceptance and purchase intent could be predicted with 81.94 and 85.49% accuracy, respectively. The logistic regression indicated that taste was the attribute that contributed significantly (P < 0.0001) to higher scores for purchase intent and was considered the driver of acceptance.