A.M. Vivar-Quintana

Discrimination of seasonality in cheeses by near-infrared technology

BACKGROUND Owing to the importance of the season of collection of milk for cheese quality, a study was made of the usefulness of near-infrared spectroscopy (NIRS) for discriminating the seasonal origin (winter or summer) of milk and quantifying the fat content of cheeses, since fat is one of the components most affected by the season of collection of milk for the elaboration of cheeses. RESULTS In the internal validation, 96% of samples from winter milk and 97% of samples from summer milk were correctly classified, while in the external validation the prediction rate of samples correctly classified was 92%. Moreover, quantitative models allowed the determination of fat in winter, summer and winter + summer cheeses. CONCLUSION Rapid prediction of the fat content of cheeses and the seasonal origin (winter or summer) of milk was achieved using NIRS without previous destruction or treatment of samples.

Pesticide residues in propolis from Spain and Chile. An approach using near infrared spectroscopy

This study analyses the presence of pesticides in 106 samples of raw propolis from Spain and Chile. The components detected and quantified using gas chromatography mass spectrometry were as follows: triamidefon present in 70.1% of the samples with concentrations between 0.35 and 42.17mg/kg, and dicofol detected in 7.5% of the samples with concentrations between 0.39 and 2.83mg/kg. Diclorofluanid, procymidone, folpet, propham and metazachlor were also detected but only in a small number of samples. Near infrared spectroscopy with a remote reflectance fibre-optic probe was used to detect samples contaminated with triadimefon via partial least squares discriminant, with a R2 value of 0.71. In addition, the presence of the pesticide triadimefon in propolis was quantified using the modified partial least squares (MPLS) regression method. The calibration results showed a coefficient of determination (R2) of 0.81, a root mean square error (RMSE) of 0.36, and a ratio of performance to deviation (RPD) of 2.5.

Determination of the Mineral Composition and Toxic Element Contents of Propolis by Near Infrared Spectroscopy

The potential of near infrared spectroscopy (NIR) with remote reflectance fiber-optic probes for determining the mineral composition of propolis was evaluated. This technology allows direct measurements without prior sample treatment. Ninety one samples of propolis were collected in Chile (Bio-Bio region) and Spain (Castilla-León and Galicia regions). The minerals measured were aluminum, calcium, iron, potassium, magnesium, phosphorus, and some potentially toxic trace elements such as zinc, chromium, nickel, copper and lead. The modified partial least squares (MPLS) regression method was used to develop the NIR calibration model. The determination coefficient (R2) and root mean square error of prediction (RMSEP) obtained for aluminum (0.79, 53), calcium (0.83, 94), iron (0.69, 134) potassium (0.95, 117), magnesium (0.70, 99), phosphorus (0.94, 24) zinc (0.87, 10) chromium (0.48, 0.6) nickel (0.52, 0.7) copper (0.64, 0.9) and lead (0.70, 2) in ppm. The results demonstrated that the capacity for prediction can be considered good for wide ranges of potassium, phosphorus and zinc concentrations, and acceptable for aluminum, calcium, magnesium, iron and lead. This indicated that the NIR method is comparable to chemical methods. The method is of interest in the rapid prediction of potentially toxic elements in propolis before consumption.

Effect of somatic cell counts on ewes' milk protein profile and cheese-making properties in different sheep breeds reared in Spain

Bulk tank ewes milks from Assaf, Castellana and Churra breeds categorized within three different Somatic Cell Count (SCC) groups (LSCC: <500,000; MSCC: 1,000,000 to 1,500,000; and HSCC: 2,500,000 to 3,000,000 cells ml-1) were used to investigate changes in capillary electrophoresis protein profiles and cheese-making properties. The results do not reveal a significant effect of SCC on total casein contents, because the sum of beta-caseins decreased as SCC increased; no statistically significant differences were observed for the sum of alpha-caseins, and the values of kappa-casein were higher in the HSCC milk. However, the soluble proteins other than alpha-lactalbumin and beta-lactoglobulin increased with SCC. Regarding the effect of breed, the Assaf breed had the lowest contents of kappa-CN, alpha s1-I-CN, alpha s1-II-CN 1-CN, alpha s1-III-CN, beta1-CN and beta2-CN. The protein profile was significantly correlated with curd textural properties. alpha s1-I-CN was the most influential variant because it was positively correlated with a large number of textural parameters. Cheese yield was positively correlated with all casein variants except alpha s1-III-CN, showing that the milk from local breeds were more suitable for cheese-making due to their higher contents of all the casein variants. Regarding curd texture properties LSCC milk curds showed more cohesiveness, associated with its lower content of alpha s1-III-CN and Castellana milk curds showed the highest values for firmness owing to their higher content of alpha s1-I-CN.

Antioxidant capacity of different cheeses: Affecting factors and prediction by near infrared spectroscopy.

In this study, we analyzed antioxidant capacity of 224 cheese samples prepared using 16 varied mixtures of milk from cows, ewes, and goats, in 2 manufacturing seasons (winter and summer), and over 6mo of ripening. Antioxidant capacity was evaluated using the spectrophotometric 2,2-azinobis(3-ethylenebenzothiazoline-6-sulfonic acid) (ABTS) method. Total antioxidant capacity was significantly correlated with season of manufacturing and time of ripening but not with animal species providing the milk. Moreover, statistically significant correlations between the total antioxidant capacity and retinol (r=0.399), fat percentage (r=0.308), protein percentage (r=0.366), K (r=0.385), Mg (r=0.312), Na (r=0.432), and P (0.272) were observed. We evaluated the use of near infrared spectroscopy technology, together with the use of a remote reflectance fiber-optic probe, to predict the antioxidant capacity of cheese samples. The model generated allowed us to predict antioxidant capacity in unknown cheeses of different compositions and ripening times.

Reducing student risks in the laboratory protocol assessment

The objective of this article is the evaluation of the work methodology proposed for a teaching laboratory designed to reduce the risks associated with the work of students in the laboratory. This design establishes protocols for action which with the help of mobile technology seek to enable students to incorporate preventive attitudes to their work routines in order to minimise the risks associated with their own work in the laboratory and to include safety regulations connected with the labels of the chemical reactants being handled. The work was carried out in the Food Technology laboratories of the Higher Polytechnic School of Zamora of the University of Salamanca.

Evaluation of the Use of Technology to Improve Safety in the Teaching Laboratory

Classroom safety, especially in laboratories, is a frequent concern in engineering. This paper addresses the results obtained from an assessment regarding the students’ use of a laboratory practice manual that incorporates the different types of technology, with the final aim of introducing good safety practices as a standard part of the teaching process. Thereby, students are encouraged to play a more active role in the process of learning.

Augmented safety in the laboratory with mobile technology

This article presents a proposal to increase the safety of students in the laboratory of Food Technology through the use of techniques of Augmented Reality.

Determination and quantification of phenolic acids in raw propolis by reversed phase high performance liquid chromatography. Feasibility study for the use of near infrared spectroscopy

In this study we analyzed the phenolic composition of 50 propolis extracts from Spain and Chile by high performance liquid chromatography (HPLC). Ten compounds were identified and quantified: caffeic acid; p-coumaric acid; cinnamic acid; ferulic acid; isoferulic acid and 3,4-dimethyl-caffeic acid (DMCA); caffeic acid benzyl ester; p-coumaric cinnamyl ester; p-methoxy cinnamic acid cinnamyl ester; and caffeic acid phenylethyl ester (CAPE). The amounts of phenolic acids found ranged from 20.1–156.4 mg/g for Spanish propolis to 1.7–37.4 mg/g for Chilean propolis. Higher amounts were found for phenolic acid derivatives in all samples analyzed with values between 23.5–132.2 mg/g in Spanish propolis and 21.0–123.0 mg/g in Chilean propolis. A new method based on Near-Infrared Spectroscopy (NIR) is used to estimate the phenolic composition of acids and acid derivatives. The results obtained show that there are no differences between the results obtained by NIR spectroscopy and the chromatographic data.

New formulations for low-fat frankfurters and its effect on product quality

The effects of reducing fat level (9% and 12%), substituting pork fat with olive oil and adding locust bean/xanthan gum on emulsion stability, jelly and fat separation, cook loss, and hardness of frankfurters were investigated and compared with control sample elaborated with 20% of fat content. Results showed that addition of locust bean/xanthan gum produced a significant increase in hydration/binding properties, characterised by lower cook losses, increasing yield, better emulsion stability and lower jelly and fat separation. The substitution of fat pork by olive oil did not affect these parameters. Multivariate comparison between elaborated low-fat products and commercial frankfurters (normal and low-fat) were carried out using a factorial analysis. Results showed that addition of locust bean/xanthan gum results in products similar to commercial frankfurters with higher fat contents.