Marta M. Calvo

Dry fermented sausages enriched with lycopene from tomato peel

Tomato industries yield a high amount of by-products mainly tomato peel and seeds. Since tomato peel is rich in lycopene, the direct addition of peel to food products could be a way to use this by-product to obtain a new products enriched in lycopene. This work describes experiments performed to develop dry fermented sausages (salchichón) containing this carotene. 0%, 0.6%, 0.9% and 1.2% (w/w) of dry tomato peel was added to the meat mixture used in sausage manufacture. A slight losts of lycopene was detected after 21 days ripening, however, levels remained between 0.26 and 0.58mg of lycopene/100g of sausage. The sensory and textural properties and overall acceptability of all sausages were good, indicating that tomato peel could be added to dry fermented sausages to produce a meat product enriched in lycopene.

Beef hamburgers enriched in lycopene using dry tomato peel as an ingredient.

The direct addition of dry tomato peel (DTP) to hamburgers may be useful both to obtain a new product enriched in lycopene and for providing a use for this by-product from the tomato industry. In this study, different amounts of DTP (0-6.0%w/w) were added to raw and cooked hamburgers, and the effects on the meats physico-chemical and sensorial characteristics were studied. The maximum DTP concentration compatible with good sensory acceptability and high lycopene content was determined. Addition of DTP increased the colour parameters a(∗) and b(∗) of raw and cooked hamburgers, and modified all textural properties probably because of the presence of fibre. The hardness values of cooked samples was significantly higher in the batch containing 6% DTP (67.6N) than in a control batch (50.9N, p<0.05). The addition of DTP to 4.5% results in hamburgers with good overall acceptability and a lycopene content of 4.9mg/100g of cooked hamburger.

Changes in the carbohydrate fraction of milk during heating processes

Abstract Carbohydrate composition of commercial pasteurized, UHT, sterilized and dried milk samples, and laboratory heat-treated milks was determined by gas-liquid chromatography. Glucose, galactose and lactulose were present in all types of commercial milk samples. The concentrations of galactose and lactulose increase with the severity of the heating process. The amount of glucose present in commercial milks was similar to that found in unheated milk. Epilactose was only detected in sterilized milk samples. UHT and sterilized milks can be differentiated by their lactulose, galactose or epilactose content.

Flavour of heated milks. A review

Abstract The flavour of fresh milk is due to the combined effect of a great number of compounds from diverse origins. This flavour may change when milk is submitted to thermal treatments. The kind and intensity of the heated milk flavour depends on the intensity of the thermal treatment. The heating of milk causes the formation of volatile compounds from milk proteins, carbohydrates and lipids, as well as from some other compounds. From milk proteins some compounds are originated via the release of sulphidryl compounds during the heat denaturation of the whey proteins and proteins in the milk fat globule membrane; other compounds are formed via the non-enzymatic browning reaction. The heating of milk produces the formation of some methyl ketones, lactones and aldehydes from milk fat. The formation of the volatile compounds, responsible for flavour of heated milk, during the heat treatment of milk has been reviewed in this work.

Influence of other whey proteins on the heat-induced aggregation of α-lactalbumin

Abstract The thermally induced aggregation of α-lactalbumin in solution and in the presence of serum protein-free casein micelles has been studied using gel permeation chromatography. No aggregation of α-lactalbumin was detected after heating at 90°C for 24 min. However, addition of β-lactoglobulin or serum albumin to the serum protein-free casein micelles + α-lactalbumin system caused aggregation of the α-lactalbumin, the rate and extent of this aggregation being dependent upon the concentration of free sulphydryl groups present in the other whey protein. It is therefore the sulphydryl group which is important and which appears to function by inducing cleavage of intramolecular disulphide bonds in the α-lactalbumin. This leads to the formation of intermolecular disulphide bridges and hence to aggregation of the α-lactalbumin.

Analysis of free carbohydrates in milk using micropacked columns

SummaryA gas chromatographic method using a micropacked column is described for the analysis of lactose, galactose, lactulose and epilactose in processed milks. The method is evaluated for precision and accuracy using phenyl-β-glucoside as an internal standard. Recoveries near 100% were found for lactulose concentrations higher than 0.1 mgml−1, showing coefficients of variation from 5.9 to 9.4%.

1H‐HRMAS NMR study of smoked Atlantic salmon (Salmo salar)

High‐resolution magic angle spinning (HRMAS) NMR spectroscopic data of smoked Atlantic salmon (Salmo salar) were fully assigned by combination of one‐ and two‐dimensional‐HRMAS experiments. Complete representative spectra, obtained after few minutes of analysis time, revealed a large number of minor and major compounds in the sample. The methodology is limited by the low sensitivity of NMR, and therefore HRMAS only enables the determination of the most relevant components. These were fatty acids (FAs), carbohydrates, nucleoside derivatives, osmolytes, amino acids, dipeptides and organic acids. For the first time, spectra were resolved sufficiently to allow semiquantitative determination in intact muscle of the highly polyunsaturated FA 22:6 ω‐3. Additionally, the feasibility of 1H‐HRMAS NMR metabolite profiling was tested to identify some bioactive compounds during storage. This profiling was carried out by the non‐destructive and direct analysis (i.e. without requiring sample preparation and multiple step procedures) of intact salmon muscle. The proposed procedure can be applied to a large number of samples with high throughput due to the short time of analysis and quick evaluation of the data. Copyright

Rennet-clotting properties and starter activity on milk acidified with carbon dioxide

The influence of acidification with CO2 on starter activity, rennet clotting properties, and cheese yield have been studied. Results obtained with lactic acid-treated milk were compared with those obtained with CO2-treated milks. CO2-treated samples showed lower acidification by starter than lactic acid-treated samples. The higher final pH values found in CO2-treated samples could be attributed to reduced starter metabolic activity. Heat treatments to 60 or 70°C for 30 min did not influence coagulation time by rennet. Acidification produced a decrease of coagulation time, which was more pronounced on samples treated with lactic acid. Cheese yield was influenced by the growth of psychrotrophic bacteria during storage of milk.

Kinetics of lactulose, galactose and epilactose formation during heat-treatment of milk

Abstract The kinetics of formation of lactulose, galactose and epilactose during heating of milk were examined over a wide temperature/time range ( 100–150° C 1–30 min ). Formation of the studied carbohydrates was best described with apparent first order reactions. The Arrhenius plot of the logarithm of the rate constant as a function of the reciprocal of the temperature (°K) enabled calculation of the activation energies (125 kJ/mol for lactulose, 131 kJ/mol for epilactose and 139 kJ/mol for galactose). By using the kinetics parameters for calculating lines of equal degrees of formation in a plot of log-time versus reciprocal of absolute temperature it was possible to predict the effect of different heat-treatments on the formation of individual carbohydrates.

Chromatographic determination of lactulose

SummaryLactulose is a disaccharide with important implications in medicine, nutrition and dairy technology. It has to be determined usually as a minor component in complex matrices containing many other sugars. This paper describes the different chromatographic techniques (planar, liquid and gas chromatography) which have been proposed for the separation and quantification of lactulose in mixtures with other carbohydrates; the advantages of each technique are compared and some features where more research is necessary are outlined.