Bioaccessibility of tocopherols, carotenoids, and ascorbic acid from milk- and soy-based fruit beverages: influence of food matrix and processing

A study was made of the effect of high-pressure processing (HPP) and thermal treatment (TT) on plant bioactive compounds (tocopherols, carotenoids, and ascorbic acid) in 12 fruit juice-milk beverages and of how the food matrix [whole milk (JW), skimmed milk (JS), and soy milk (JSy)] modulates their bioaccessibility (%). HPP (400 MPa/40 °C/5 min) produced a significant decrease in carotenoid and ascorbic acid bioaccessibility in all three beverages and maintained the bioaccessibility of tocopherols in JW and JS while decreasing it in JSy. TT (90 °C/30 s) produced a significant decrease in tocopherol and carotenoid bioaccessibility in all three beverages and increased the bioaccessibility of ascorbic acid. With regard to the food matrix, α-tocopherol and ascorbic acid bioaccessibility was greatest in JW beverages and lowest in JSy beverages, whereas no significant differences were found among the three beverages in terms of carotenoid bioaccessibility. HPP-treated samples showed higher tocopherol and carotenoid bioaccessibility than TT-treated samples, thus indicating that HPP combined with a milk matrix positively modulates the bioaccessibility of certain types of bioactive components of food, mainly those of a lipophilic nature.     

Humic acids buffer the effects of urea on soil ammonia oxidizers and potential nitrification

Humic acids (HAs) play an important role in the global nitrogen cycle by influencing the distribution, bioavailability, and ultimate fate of organic nitrogen. Ammonium oxidation by autotrophic ammonia-oxidizing bacteria (AOB) is a key process in ecosystems and is limited, in part, by the availability of NH₄⁺. We evaluated the impact of HAs on soil AOB in microcosms by applying urea (1.0%, equal to 10 mg urea/g soil) with 0.1% bHA (biodegraded lignite humic acids, equal to 1 mg/g soil), 0.1% cHA (crude lignite humic acids) or no amendment. AOB population size, ammonium and nitrate concentrations were monitored for 12 weeks after urea and HA application. AOB densities (quantified by real-time PCR targeting the amoA) in the Urea treatments increased about ten-fold (the final abundance: 5.02 × 10⁷ copies (g of dry soil)⁻¹) after one week of incubation and decreased to the initial density after 12 weeks incubation; the population size of total bacteria (quantified by real-time PCR with a universal bacterial probe) decreased from 1.12 × 10¹⁰ to 2.59 × 10⁹ copies (g of dry soil)⁻¹ at week one and fluctuated back to the initial copy number at week 12. In the Urea + bHA and Urea + cHA treatments, the AOB densities were 4 and 6 times higher, respectively, than the initial density of approximately 5.07 × 10⁶ copies (g of dry soil)⁻¹ at week 1 and did not change much up to week 4; the total bacteria density changed little over time. The AOB and total bacteria density of the controls changed little during the 12 weeks of incubation. The microbial community composition of the Urea treatment, based on T-RFLP using CCA (canonical correspondence analysis) and pCCA (partial CCA) analysis, was clearly different from those of other treatments, and suggested that lignite HAs buffered the change in diversity and quantity of total bacteria caused by the application of urea to the soil. We hypothesize that HAs can inhibit the change in microbial community composition and numbers, as well as AOB population size by reducing the hydrolysis rate from urea to ammonium in soils amended with urea.     

A kinetic study on the isomerization of hop alpha-acids

In this article, a detailed study on hop alpha-acid isomerization kinetics is presented. Because of the complex wort matrix and interfering interactions occurring during real wort boiling (i.e., trub formation and alpha-acids/iso-alpha-acids complexation), this investigation on alpha-acid isomerization kinetics was performed in aqueous buffer solution as a function of time (0-90 min) and heating temperature (80-100 degrees C). Rate constants and activation energies for the formation of individual iso-alpha-acids were determined. It was found that iso-alpha-acid formation follows first-order kinetics and Arrhenius behavior. Differences in activation energies for the formation of trans- and cis-isomers were noticed, the activation energy for the formation of trans-iso-alpha-acids being approximately 9 kJmol (-1) lower.     

Vinasse irrigation: effects on soil fertility and arbuscular mycorrhizal fungi population

Purpose

The aim of this research was to determine the vinasse irrigation effects on the arbuscular mycorrhizal fungi (AMF) population (total spore abundance (TSA), richness, relative abundance, and diversity indices) and soil parameters and nutrients at high doses. The irrigation of soil with vinasses derived from sugarcane, beet, or alcohol production is a common practice around the world. Little is known about how this affects the AMF community and soil nutrients.

Materials and methods

The spider plant (Chlorophytum comosum, (Thunb.) Jacques), a mycorrhizable plant, was used to investigate the effect of 4 months of frequent vinasse irrigation (0, 25, 50, 75, and 100% vinasse concentration) on AMF and soil characteristics, e.g., electrical conductivity (EC), pH, mineral N, available P, Na⁺, K⁺, Ca²⁺, and Mg²⁺.

Results and discussion

The vinasse irrigation decreased the TSA, AMF richness and diversity after 4 months, regardless of vinasse concentration. The vinasse irrigation did not acidify the soil, but the EC, mineral N and available P increased. The biomass of C. comosum decreased (77–81%) after vinasse irrigation for 4 months.

Conclusions

Frequent irrigation with vinasse at concentrations ≥50% increases EC, K⁺, Na⁺, Mg²⁺, Ca²⁺ and available P in the soil, and decreases the amount of AMF spores, richness and diversity, which is not desirable in agricultural soils.