Effect of a cold‐active pectinolytic system on colour development of Malbec red wines elaborated at low temperature

The effect of a new cold‐active pectinolytic system on colour of Malbec wines was studied under the following winemaking conditions: (i) fermentation at low temperature (20 °C) and (ii) prefermentative cold maceration (PCM) (5 °C–7 days) followed by traditional fermentation (28 °C). The pectinolytic system was mainly composed of polymethylgalacturonase and pectin lyase activities, detected under similar conditions to those in winemaking (pH 3.6–20 °C). The results show that the enzyme system significantly accelerated colour extraction by reducing the maceration time necessary for vinification at low temperature and shortening the PCM stage. Enzyme‐treated wines exhibited better chromatic parameters than their controls at devatting and after 6 months of storage. The cold‐active enzyme compensated the decrease in colour extraction due to the low maceration temperature, achieving high‐quality wines with chromatic characteristics similar to those of traditional wines.     

Texture Prediction in Intact Green Asparagus by Near Infrared (NIR) Spectroscopy,Assaying Linear and Non-linear Regression Strategies

Texture-related parameters were assessed in intact green asparagus at harvest and during postharvest storage using near-infrared spectroscopy combined with MPLS and LOCAL algorithms. Three spectrophotometers were evaluated for this purpose: a monochromator (range, 400–2,500 nm), a diode-array Vis–NIR spectrophotometer (range, 400–1,700 nm), and a handheld micro-electro-mechanical system (MEMS) spectrophotometer (range, 1,600–2,400 nm). Three hundred green asparagus spears (cv. “Grande”) were used to obtain calibration models based on reference data and NIR data. Results for maximum shear force showed that LOCAL algorithm improved the predictive capacity of models constructed using all three NIRS instruments, increasing r ² by 24, 16, and 56 % and reducing the SEP(c) values by 11, 8, and 14 %, respectively. For cutting energy, the LOCAL also improved the predictive capacity of the models (r ² increased by 3 % for the monochromator and the diode-array instrument and by 6 % for the MEMS device; and the SEP(c) decreased by 3 % in the three instruments). It is worth noting that while the monochromator and diode-array instruments displayed similar predictive capacity for the parameters tested, the MEMS instrument achieved slightly poorer results but has clear advantages for the measurement of texture in intact asparagus, being economical, portable, and easy to use in situ.     

Health-promoting effects in the gut and influence on lipid metabolism of Himanthalia elongata and Gigartina pistillata in hypercholesterolaemic Wistar rats

The intake of Himanthalia elongata and Gigartina pistillata from the Spanish Atlantic coasts was evaluated in Wistar rats. Both seaweed diets showed higher (p < 0.001) faecal excretion. Colonic fermentation increased (p < 0.001) total short-chain fatty acids (SCFAs) in Himanthalia-fed rats due to the higher (p < 0.001) levels of acetic, propionic and butyric acids. The intake of Gigartina increased (p < 0.001) propionic acid and decreased (p < 0.001) butyric acid. The apparent absorption and true retention of calcium and magnesium enhanced (p < 0.05) with Himanthalia diet, while Gigartina produced no significant effect. The serum concentration of HDL-C increased (p < 0.01), triglycerides (TGL) decreased (p < 0.001) and bile acids diminished (p < 0.001) in faeces of Himanthalia-fed rats. The Gigartina diet produced a decrease (p < 0.001) in TGL, total cholesterol (p < 0.01) and LDL-C (p < 0.05) in serum and reduced TGL in liver (p < 0.001). Thus, both seaweeds improved the lipid profile, and Himanthalia increased SCFA production and the absorption and retention of Ca and Mg as a result of the gut fermentation.     

Determination of Phenolic Compounds in Artichoke,Garlic and Spinach by Ultra-High-Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry

Phenolic compounds were determined in artichoke (Cynara scolymus), garlic (Allium sativium) and spinach (Spinacia oleracea) using a single method based on simple extraction and ultra-high-performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS). Several compounds belonging to different families, such as phenolic acids, isoflavones, flavones and flavonols, were determined. The analytical procedure was validated in all the matrices, obtaining recoveries ranging from 60 to 120 % with reproducibility values (expressed as relative standard deviations (RSDs)) lower than 26 %. Limits of quantification (LOQs) were always equal to or lower than 50 μg/kg, except to kaempferol and its glucosides in spinach (LOQs?=?75 μg/kg). Artichoke showed higher concentration of phenolic compounds (837.2 mg/kg dry weight (DW)) than garlic (26.5 mg/kg DW) or spinach (64.5 mg/kg DW). Apigenin 7-O-glucoside (from 147.0 to 722.7 mg/kg DW) was found to be the major flavonoid in all samples of artichoke investigated, while chlorogenic acid, whose concentration ranged from 37.8 to 734.7 mg/kg DW, is the major phenolic acid in this matrix. Regarding garlic, caffeic acid (from 1.7 to 28.3 mg/kg DW) and quercetin (from 9.0 to 18.9 mg/kg DW) were the compounds detected at higher concentrations, although in general the total content was very low in relation to other matrices. In relation to spinach, ferulic acid was the major phenolic compound, and its concentration ranged from 18.0 to 41.4 mg/kg DW.     

Influence of Homogenization Conditions on Physical Properties and Antioxidant Activity of Fully Biodegradable Pea Protein–Alpha-Tocopherol Films

In this study, antioxidant biodegradable films based on pea protein and alpha-tocopherol were successfully developed by solution casting. The effect of both the homogenization conditions (rotor–stator and microfluidizer) and the relative humidity (RH) on the microstructure and physical properties (transparency, tensile, oxygen and water vapour barrier properties) of pea protein/alpha-tocopherol-based films was evaluated. The addition of alpha-tocopherol produced minimal changes in the films’ transparency, while providing them with antioxidant properties and improved water vapour and oxygen barrier properties (up to 30 % in both water vapour and oxygen permeability) when films were at low and intermediate RH. The addition of alpha-tocopherol in microfluidized films gave rise to an increase in their resistance to break and extensibility (up to 27 % in E values) at intermediate and high RH. These results add a new insight into the potential of employing pea protein and alpha-tocopherol in the development of fully biodegradable antioxidant films which are of interest in food packaging.     

Evaluation of Norrish’s Equation for Correlating the Water Activity of Highly Concentrated Solutions of Sugars,Polyols, and Polyethylene Glycols

Norrish’s equation, a_\textw = X_\textw exp( - KX²_\texts )a_{{\text{w}}} = X_{{\text{w}}} \exp {\left( { - KX^{2}_{{\text{s}}} } \right)}, where a _w is water activity, X _w and X _s are molar fractions of water and solute, respectively, and K is the correlating constant, has been widely used to predict a _w of aqueous nonelectrolyte solutions in connection with development of intermediate moisture foods, i.e., food having a _w ≥ 0.85. Present work evaluated the ability of Norrish’s equation to model the water activity of solutions of sugars, polyols, and some polyethylene glycols, in a wide range of concentration, i.e., from low to highly concentrated solutions. For sugar and polyols, a relatively small modification of the “most accepted” literature parameters K allowed the fitting of the data for the wide range of solute concentrations corresponding to a range of a _w from 0.99 to about 0.3 for same solutes. However, a modified Norrish’s model needs to be used to model the behavior of polyethylene glycols 400 and 600 up to water activities as low as 0.5.     

Extracts of Mexican Oregano (<Emphasis Type="Italic">Lippia berlandieri</Emphasis> Schauer) with Antioxidant and Antimicrobial Activity

Antimicrobial activity of fractions obtained from Mexican oregano (Lippia berlandieri Schauer) chloroform extract was tested by growth inhibition against Escherichia coli, Staphylococcus aureus and Bacillus cereus, and antioxidant capacity was tested by inhibition of linoleic acid oxidation. Fractions were obtained by differences in polarity or structure (phenolic and non-phenolic fraction). Gram-positive organisms were more susceptible to Mexican oregano extracts. Fraction 3 (by polarity) and phenolic fractions I, II, III, IV and V were the extracts with higher antimicrobial activity. The non-phenolic fraction had effect against B. cereus. Polarity fraction 5 and phenolic Fraction II had a high antioxidant capacity; a 0.08% concentration of fraction 5 had a similar effect as butylated hydroxytoluene at 0.01% concentration. Fractions of Mexican oregano with different polarity and functional groups had antioxidant and antimicrobial activity and can be used in a variety of applications.     

Anthocyanin composition of Tempranillo, Garnacha and Cabernet Sauvignon grapes from high- and low-quality vineyards over two years

The anthocyanin composition of Tempranillo, Garnacha and Cabernet Sauvignon grapes over two vintages was studied. Samples were obtained during berry ripening from two vineyards that differed by producing fruit of high and low quality. The proportions of the individual compounds remained practically constant within a single vineyard along the sampling period, the changes in the anthocyanin composition being principally quantitative. Different multivariate statistical methods showed that the anthocyanin profile was primarily determined by variety. This genetic dependence was particularly verified when the sums of the non-acylated glucosides, the acetates and the p-coumaryl derivatives, were analysed. The mean relative content corresponding to these three anthocyanin fractions was always the same within each variety, independently either of the vineyard or the vintage year considered. Relating to the individual compounds, several permanent qualitative differences between vineyards in each variety were also found, although the difference in the total anthocyanin concentration was always much higher.     

Evaluation of the spiral plating method for the enumeration of microorganisms throughout the manufacturing and ripening of a raw goat's milk cheese

A statistical comparison of the spiral plate count (SPLPC) and the standard plate count (SPC) methods for enumeration of microorganisms in raw goat's milk cheese throughout its manufacturing and ripening was carried out. Enumeration of mesophiles, lactic acid bacteria (presumptive lactococci, presumptive leuconostocs, and presumptive lactobacilli), Micrococcaceae, Enterobacteriaceae, and molds and yeasts was carried out for milk, curd, and 2-, 5-, 10-, 17-, and 27-day-old cheeses. Average counts for the SPLPC and SPC methods differed by less than half of a log cycle for all microbial groups studied (range of difference, -0.1386 [mesophiles] to +0.4397 [presumptive lactobacilli]). The results of the SPLPC method compared favorably with the results of the SPC procedure for mesophiles, presumptive lactococci, presumptive leuconostocs, Enterobacteriaceae, and molds and yeasts (the variance between replicate platings was close to 0.005, and correlation coefficients were >0.9). Correlation coefficients were lower for Micrococcaceae (r = 0.824) and presumptive lactobacilli (r = 0.670). Analysis of variance showed that the plating method was a significant factor (P < 0.05) for presumptive lactobacilli counts. In general, results from the SPLPC method compared favorably with results from SPC procedure in the enumeration of microorganisms in goat cheese throughout its manufacturingand ripening processes. However, the suitability of the SPLPC method depends mainly on the microbial group studied.     

HPLC quantification of biogenic amines in cheeses: correlation with PCR-detection of tyramine-producing microorganisms

The consumption of food and beverages containing high amounts of biogenic amines (BA) can have toxicological effects. BA found in foods and beverages are synthesized by the microbial decarboxylation of certain amino acids. This paper reports the concentrations of BAs in a number of commercial cheeses, as determined by HPLC. The cheeses studied were made from raw and pasteurized milk of different origin, and were subjected to different ripening periods. BA concentrations were lower in short ripening period than in long ripening period cheeses, and higher in cheeses made from raw milk than in those made from pasteurized milk. The highest BA concentrations were recorded in blue cheeses made from raw milk. Tyramine was the most commonly recorded and abundant BA. The presence of tyramine-producing bacteria was determined by PCR, and a good correlation obtained between the results of this method and tyramine detection by HPLC. These methods could be used to complement one another in the detection and quantification of tyramine in cheese prevention of tyramine accumulation in cheese.