Determination of sensory thresholds of Mentha piperita L. essential oil in selected tropical fruit juices and efficacy of sensory accepted concentrations combined with mild heat to inactivate foodborne pathogens

This study determined the compromised acceptance threshold (CAT) and rejection threshold (RT) of Mentha piperita L. essential oil (MPEO) in cajá, guava and mango juices. The MPEO concentrations below the RT values were evaluated alone or combined with mild heat treatment (MHT; 54 °C) to inactivate ≥5-log₁₀ of Escherichia coli O157:H7 and Salmonella Enteritidis PT 4 in the same juices. The CAT of MPEO varied from 0.30 to 0.32 μL mL⁻¹, while the RT was 1.34 or 1.36 μL mL⁻¹ in the tested juices. Only concentrations of MPEO close, or higher than the RT caused ≥5-log₁₀ reductions in the tested pathogens in cajá, guava and mango juices. Combined with MHT, concentrations of MPEO below the RT reduced ≥5-log₁₀ of both pathogens in juices. These findings indicate that MPEO concentrations below the RT in combination with MHT is a feasible preservation technology to ensure the safety of tropical fruit juices.     

Antioxidant and antibacterial activities of a starch film with bioextracts microencapsulated from cactus fruits (Opuntia oligacantha)

Food Science and Biotechnology - The use of unconventional sources is very relevant in the food area. In the present study the development of active films with the addition of bioextract (BE) or...     

Risk factors associated with lameness and hoof lesions in pasture-based dairy cattle systems in southeast Brazil

Cattle lameness is an important welfare concern that also has an economic impact on the dairy industry. It can be a significant problem among pasture-based herds. Our objectives were to identify cow- and herd-level factors related to lameness and hoof lesions in dairy cows grazing year-round in Minas Gerais, Brazil. We performed a cross-sectional study in 48 pasture-based dairy herds, visiting each farm in a single visit. We evaluated 2,262 cows for mobility score (0–3) and 392 cows for hoof lesions. We used a questionnaire and checklist to capture herd management data. All information obtained was used to build multivariable models. The factors associated with lameness were low body condition score, longer time spent in the corral, being kept in paddocks during the drought period, and poor hygiene. For hoof lesions, track features were the most significant factor in determining the likelihood of heel horn erosion, white line fissure, and sole hemorrhage—by more than 3 times. Different factors related to unhygienic conditions such as leg cleanliness, frequency of cleaning, and longer time spent in the corral were associated with infectious hoof lesions. Poor human–animal relationship was related to sole hemorrhage, but patient handling of cows on the track was a protective factor against interdigital hyperplasia. The results of this study suggest that improving hygiene conditions, track features, and cow handling can improve dairy cattle mobility scores in pasture-based farms under tropical conditions. These findings also represent a first step toward planning actions aimed at decreasing lameness and hoof lesions in the studied region.     

Predicting heat inactivation of Staphylococcus aureus under nonisothermal treatments at different pH

The aim was to assess whether heat resistance data obtained from isothermal treatments allow the estimation of survivors of Staphylococcus aureus under nonisothermal conditions and to find a model that accurately predicts its heat inactivation at constantly rising heating rates (0.5-9 degrees C/min) in media of different pH (4.0-7.4). S. aureus showed a higher heat resistance under isothermal treatments at pH 4.0 than at pH 5.5-7.4. However, under nonisothermal treatments S. aureus increased its heat resistance at pH 5.5-7.4 and became more thermotolerant than at pH 4.0. Estimations of survival curves under nonisothermal treatments obtained from heat resistance parameters of isothermal treatments did not adequately fit experimental values. Whereas the number of survivors was much higher than estimated at pH 5.5-7.4, that obtained at the slower heating rates at pH 4.0 was lower. An equation based on the Weibullian-like distribution (log10 S(t) = (t/delta)p) accurately described survival curves obtained under nonisothermal conditions. A nonlinear relationship was observed among the scale parameter (delta) and the heating rate which allowed the development of two equations capable of predicting the inactivation rate of S. aureus under nonisothermal treatments. This study might contribute to prevent public health risks in foods requiring long heating lag phases during their processing.     

Amino acid composition of wheat grain. 1: Changes during development

The changes in the composition of free and total amino acids in wheat grain during development are described: the experiment was performed in a growth chamber with three varieties of winter wheat (Triticum aestivum L.): Splendeur, Hobbit and Maris Huntsman. The changes in the total composition of amino acids of the grain as development progressed were consistent with an increase in the proportion of storage proteins. At 15 days after anthesis, the relative amount of glycine increased, suggesting that at this moment the proportion of gliadins was relatively low. The relative amount of arginine increased in mature grain, showing that at times close to maturity the relative proportion of synthesis of a protein fraction rich in this amino acid increased. Free glutamate, proline and arginine decreased at 15 days to a greater extent than the other amino acids and was present in low relative amounts during the period of maximum protein synthesis in the grain; these three amino acids could be the most limiting for protein synthesis in grain. In the free fraction the following showed a similar pattern of change during grain development: aspartate, arginine and histidine on the one hand, and on the other alanine, valine, leucine, isoleucine, threonine, phenylalanine and tyrosine; moreover both groups were inversely correlated. Glycine and lysine were directly related to each other and inversely to glutamate.     

Comparison of Different Extraction Methods to Determine Phenolic Compounds in Virgin Olive Oil

A comparison between different extraction methods has been performed in order to assess their effectiveness for the analysis of total phenols (liquid–liquid extraction (LLE), liquid–liquid micro extraction (LLME), and ultrasound liquid–liquid extraction (USE)) and individual phenols (LLME, USE, and solid-phase extraction (SPE)) from virgin olive oil (VOO). Statistical analysis of the analytical data obtained for the total phenol content of a VOO, showed that LLME and USE can represent a reliable alternative to the traditional procedure based on LLE that needs more amount of sample, generates more wastes, and is more time consuming. When an olive oil spiked with phenols was used to test the efficiency of LLME, USE, and SPE methods, the statistical analysis of the data obtained for each individual phenol, again proved LLME and USE methods to be the most suitable, in terms of precision and recoveries, for this purpose. The analysis of real samples (Arbequina and Picual cultivars) confirmed the results obtained for the spiked oil.     

In vitro and in vivo antioxidant activity of musts and skin extracts from off-vine dried Vitis vinifera cv. “Tempranillo” grapes

The phenolic composition and antioxidant activity of musts and skin extracts from Tempranillo grapes dried for variable lengths of times were examined here. Both were found to increase in the grape must with increasing drying time, but the opposite trend was observed in the skin extracts. The antioxidant activity of the must and skin was largely due to anthocyanins. Also, the anthocyanins fraction exhibited the highest antioxidant activity per gram of phenolic compound in the musts and skin extracts at the end of the drying process, polymeric pigments and high-molecular-weight procyanidins were also prominent in this respect. In vivo antioxidant activity in terms of protein oxidation and survival of Saccharomyces cerevisiae cells previously incubated with 10 μg/mL of polyphenols from the musts and skins and exposed to hydrogen peroxide was also measured. Both extracts exerted a protective effect against oxidative stress, the effect increasing with increasing dehydration time and being somewhat higher for skin than for must. Thus, must and skin from dehydrated grapes possess antioxidant properties, which allow the latter, a by-product of sweet wine, to be used as a natural source of antioxidants.     

Deacidification of Soybean Oil by Ion Exchange

This work investigated the deacidification of soybean oil by ion exchange using a fixed bed loaded with the strong anionic resin Amberlyst A26 OH. Degummed soybean oil was dissolved in isopropanol and the deacidification process was studied according to an experimental design based on two factors, the feed flow rate and its content of free fatty acids. The responses of interest were the solute recovery efficiency and the bed utilization efficiency, both calculated from breakthrough curves. Oil samples before and after deacidification by ion exchange, as well as samples deacidified in the industrial plant by the chemical method, were characterized according to the usual indexes for quality and identity. The results revealed that the flow rate was an important and statistically significant factor with 95 % of confidence. The deacidification by ion exchange decreased the oil acidity and also removed undesirable compounds, such as phospholipids and peroxides. However, a decrease in the concentration of tocopherol was also observed.