Maria Cristina Messia

Quality evaluation of peaches and nectarines by electrochemical and multivariate analyses: relationships between analytical measurements and sensory attributes

Abstract A propagation programme for peaches and nectarines has been targeted to select genotypes having taste attributes such as high sugar levels and well-balanced sugar/acid ratios. The analytical measurements of some soluble sugars and nonvolatile acids were carried out using innovative analytical procedures based on fast and selective devices which require very little or no sample pre-treatment whatsoever. These devices have found a unique application in detecting fructose, glucose and malic acid for the improvement of fruit genetics. The present study examines relationships between the analytical measurements of sugars and non-volatile acids and the sensory attributes (sweetness and sourness) of 21 peach and nectarine cultivars. Certain chemical parameters were correlated with the organoleptic acceptance of common commercial cultivars and recently introduced high and low-acid genotypes. Multivariate statistical analyses were found to be useful in describing the variability of the chemical and sensory parameters which characterise peach quality, as they enabled the identification of sets of variables that could be used to classify peaches and nectarines into high and low-acid categories. Malic and citric acids, minor components of these fruits, were important taste attributes as they contributed to the sensory perception of sourness.

Heat-treated milk differentiation by a sensitive lactulose assay

Abstract A sensitive enzymatic assay for determining lactulose (detection limit=2.5 mg/l; RSD

Satiating Effect of a Barley Beta-Glucan–Enriched Snack

Objective: Increasing viscous dietary fiber in snacks may have several nutritional advantages, especially for adolescents. Having a snack that may exert direct health benefits and that may, at the same time, contribute to the voluntary reduction of energy intake through modulation of appetite may be a useful dietary strategy for energy control in adolescence. In this short-term study, a new type of biscuit containing 5.2% barley β-glucan was produced and its effect on appetite moods and food intake was investigated. Methods: Twenty healthy adolescents were selected and randomly assigned to receive, as a midmorning snack, a 628 kJ (SP) or 1884 kJ (LP) preload of barley β-glucan–enriched (BB) or control (CB) biscuits. Appetite ratings before and within 2 hours following the snack, as well as the energy intake at lunch, were recorded. Results: For all sensations, a peak at 15 minutes post-snack and a subsequent return to baseline value were shown. A decrease of the area under the curve (AUC) of the desire to eat and an increase of the AUC of fullness and satiety were recorded with SP-BB compared to SP-CB. The energy intake recorded at the lunch test was always significantly lower than that at the control lunch only in females (3048 kJ vs. 3890 kJ) independently from the type of snack consumed. Total energy intake significantly correlated with preload values both in females and in males, but not with the type of biscuit. Nutritional composition of meals consumed ad libitum did not vary significantly from those with different preloads. Conclusions: The BB, consumed as a midmorning snack, although able to influence appetite ratings, did not modify food intake in a short time period.

Fast Analysis of Lysine in Food Using Protein Microwave Hydrolysis and an Electrochemical Biosensor

Abstract A fast procedure for lysine analysis in food was developed by coupling in sequence a microwave protein hydrolysis technique with a lysine enzyme electrode. Protein hydrolysis was carried out in 6N HCl using sealed vessels located in a microwave digestion system. Parameters such as irradiation power, pressure, time and temperature were varied to select the best conditions for the hydrolysis. The hydrolysate was then analyzed for lysine using an electrochemical biosensor based on an amperometric H2O2 transducer and the enzyme lysine oxidase covalently immobilized on a preactivated polymer support. Analytical parameters, such as pH, buffer and measurement system were studied in order to eliminate or minimize the enzymatic interferences. Bovine serum albumin and two farro (T. dicoccum) meals (whole and sieved) were processed for lysine content. The analysis was carried out with this new procedure (microwave hydrolysis + biosensor) and by traditional hydrolysis coupled with ion-exchange chromatography...

Influence of storage conditions on cholesterol oxidation in dried egg pasta.

The oxidative characteristics of three different egg coproducts, namely, pasteurized eggs obtained from hens bred with organic methods (POE), pasteurized eggs from conventional breeding (PCE) and pasteurized spray-dried eggs (SPCE) obtained from conventional breeding, were analyzed. SPCE samples showed the highest content of peroxide (PV) and cholesterol oxides (COPs). In contrast, pasteurized eggs from organic breeding had the lowest index of oxidation. The three egg coproducts were used to produce dried egg pasta (spaghetti). The spaghetti was stored for 12 months at room temperature using typical pasta packaging (polypropylene foil) both under light, typical of retail conditions, and in the dark. Peroxide values and cholesterol oxidation were monitored at time 0 and then quarterly for 12 months. The oxidative parameters were significantly different in various egg coproducts, but the peroxide values of pasta were in the range of 3.0-3.5 mequiv of O(2)/kg of fat, with no differences in the types of pasta prepared with the various egg coproducts. Samples stored in the dark did not show any significant variations in peroxide values. However, PCE, SPCE and POE spaghetti stored in typical packaging increased the PV by 742.8, 846.7 and 625.7%, respectively. The pasta at time 0 showed COP values of about 50 microg of COPs/g of fat. During storage, COP values increased significantly. PCE, SPCE and POE spaghetti stored in the dark showed a content of total cholesterol oxides that was 2.0, 2.0, and 1.5 times lower than that of samples stored with typical pasta packaging.

A Maltose Biosensor for Determining Gelatinized Starch in Processed Cereal Foods

ABSTRACT A reliable method for the quantitative determination of gelatinized starch in processed cereal foods was developed. It consists of an electrochemical biosensor based on amyloglucosidase and glucose oxidase enzymes co-immobilized on a Pt electrode surface, and a third enzyme, α-amylase, added in solution. Analytical parameters such as time, temperature, and enzyme units were optimized. The degree of starch gelatinization was determined in different processed cereal foods using the biosensor method and the results were commensurate to those obtained with the reference method. The biosensor methods showed good accuracy (r2 = 0.9629; relative error <12%) and comparable precision (RSD <5%). This electrochemical system is rapid, reliable, inexpensive, user-friendly for unskilled operators, and can be a valid alternative to the methods traditionally used for gelatinized starch analysis.

Kinetics of carotenoids degradation and furosine formation in dried apricots (Prunus armeniaca L.)

The kinetics of carotenoid and color degradation, as well as furosine formation, were investigated in apricot fruits during convective heating at 50, 60 and 70°C. Degradation of carotenoids and color, expressed as total color difference (TCD), followed a first and zero order kinetic, respectively. The activation energy (Ea) for carotenoids degradation ranged from 73.7kJ/mol for 13-cis-β-carotene to 120.7kJ/mol for lutein, being about 91kJ/mol for all-trans-β-carotene. Violaxanthin and anteraxanthin were the most susceptible to thermal treatment. The furosine evolution was fitted at zero order kinetic model. The Ea for furosine formation was found to be 83.3kJ/mol and the Q10 (temperature coefficient) varied from 1.59 to 4.14 at the temperature ranges 50-60°C and 60-70°C, respectively.

Dietary fiber and flavan-3-ols in shortbread biscuits enriched with barley flours co-products

The coarse fraction obtained by air classification of barley flour, rich in dietary fiber and flavan-3-ols, was utilized to develop functional biscuits. The flavan-3-ol content, antioxidant activity and oxidative stability of biscuits were measured during storage under retail conditions for 1 year. The replacement of 60% (w/w) refined wheat flour with barley coarse fraction increased the ash, fiber and flavan-3-ol contents significantly. Biscuit samples enriched with barley coarse fraction had a significantly higher amount of fiber compared with the control sample (six times higher). The β-glucan content in enriched samples was 15 times higher than control samples. The flavan-3-ol loss in biscuits after baking was about 67%. The initial content of flavan-3-ols increased from 0.6 to 4.3 mg/100 g in biscuits formulated with barley coarse fraction and showed improved antioxidant properties. Lipid oxidation increased during the shelf-life; the enriched biscuit showed the higher lipid oxidation status, but the level reached during the shelf-life was lower than the limit of acceptance reported for bakery products and, for this reason, does not compromise the safety.

Determination of Damaged Starch in Wheat Flour Using an Electrochemical Bienzyme Maltose Probe

Abstract The development of an electrochemical biosensor based on a bienzyme maltose probe and a third enzyme α-amylase in solution is reported for the rapid and inexpensive determination of damaged starch. Analytical parameters, such as probe stability, pH, temperature and response time, were optimised. Damaged starch was measured in the range of 5 × 10−6 - 5 × 10−4 mol/L as maltose produced by the enzymatic reaction and the detection limit was calculated according with the free maltose and/or glucose in the sample. The damaged starch was determined in different wheat flours, and the data significantly correlated with those obtained using a reference procedure (r2 = 0.994; P ≤ 0.0001). In addition the results showed a comparable precision (CV < 5%). This method is rapid, inexpensive and friendly for unskilled operators.

Influence of drying temperatures on the quality of pasta formulated with different egg products

The effect of egg products and drying temperatures on dried egg pasta quality has been considered. Two diagrams of temperature and three egg products were used to develop dried egg pasta. Analyses of furosine and color indexes have been carried out on pasta samples to evaluate the impact of ingredients and drying temperatures on pasta quality. The results confirmed that high drying temperatures caused higher nutritional losses compared with low drying temperatures; in fact, these samples showed a furosine content from 3.3 to 4.7 times higher than the other ones. In addition, the cholesterol oxidation increased 1.6–2 times when high temperature was applied. The only exception has been noticed on pasta formulated with eggs from hens bred with organic method; in fact, the higher tocopherols amounts in these egg products compared with egg products from conventional breeding limited the cholesterol oxidation.