Protocatechuic acid as an inhibitor of lipid oxidation in meat.

Lipid oxidation is the principal driver of meat and meat product deterioration during shelf life, causing the loss of fresh meat color, flavor, and aroma. Currently, synthetic antioxidants are used to prevent oxidation, but increasing consumer demand for natural ones leaves the industry with few alternatives. In this study, protocatechuic acid (PCA), known to have high antioxidant activity, was evaluated as a potential inhibitor of meat lipid oxidation. For this purpose, the antioxidant capacity and lipoxygenase (LOX) inhibitory activity of PCA were evaluated in vitro, and a set of four experiments was conducted, treating minced meat with water (control), lactic acid (LA), rosmarinic acid (RA) and PCA, at different concentrations (1-12 mg mL-1), depending on the experiment. The potential antioxidant effect of PCA when applied to meat cubes was also evaluated, as well as the potential of carboxymethyl cellulose (CMC) as a delivery system for PCA. The in vitro results showed that PCA is a potent antioxidant and an effective LOX inhibitor at 1 mg mL-1. PCA effect on meat lipid oxidation prevention was dose-dependent, and at 2 mg mL-1, it inhibited color change by 50% and lipid peroxidation by up to 70% when compared to water-treated samples, performing better than RA at 0.25 mg mL-1. These results suggest that PCA is a promising molecule to the meat industry as a natural preservative for meat and meat products directly or in a formulation.

Antioxidant effects of phenolic extract from sugarcane straw and mannan extract from brewer's spent yeast on fresh-cut apples.

BACKGROUND: Fresh-cut fruit are convenient ready-to-eat products increasingly demanded by consumers, but highly susceptible to oxidation. To increase the shelf life of these products, this industry is currently facing the challenge of finding sustainable natural preservatives capable of maintaining fresh-cut fruit quality while meeting consumers' expectations regarding health and environmental concerns. RESULTS: In this work, fresh-cut apple slices were treated with two antioxidant extracts derived from industrial by-products: a phenolic-rich extract produced from sugarcane straw (PE-SCS) and applied at 15 g L-1 , and a mannan-rich extract obtained from brewer's spent yeast (MN-BSY) applied at two concentrations: 1 and 5 g L-1 . PE-SCS, having a brown color, imparted a brownish hue to the fruit and increased the browning rate during storage, and not even the initial robust antioxidant response (high superoxide dismutase, catalase, ascorbate peroxidase and guaiacol peroxidase activities), prevented oxidation. Fruit treated with MN-BSY extract at 5 g L-1 showed lower color loss rate and higher polyphenol oxidase inhibition, while at 1 g L-1 it showed lower firmness loss rate and lower lipid peroxidation after 6 days of storage. CONCLUSION: The results showed that PE-SCS triggers a potent antioxidant response in fresh-cut fruit and, despite it imparting a brown color to the fruit at 15 g L-1 , it may have potential for application at lower concentrations. Regarding MN-BSY, it generally decreased oxidative stress, but its effect on quality maintenance was dependent on the concentration and, thus, to confirm its potential as a fruit preservative more concentrations must be tested. © 2023 Society of Chemical Industry.

Growth and Nutritional Responses of Bean and Soybean Genotypes to Elevated CO2 in a Controlled Environment.

In the current situation of a constant increase in the atmospheric CO2 concentration, there is a potential risk of decreased nutritional value and food crop quality. Therefore, selecting strong-responsive varieties to elevated CO2 (eCO2) conditions in terms of yield and nutritional quality is an important decision for improving crop productivity under future CO2 conditions. Using bean and soybean varieties of contrasting responses to eCO2 and different origins, we assessed the effects of eCO2 (800 ppm) in a controlled environment on the yield performance and the concentration of protein, fat, and mineral elements in seeds. The range of seed yield responses to eCO2 was - 11.0 to 32.7% (average change of 5%) in beans and -23.8 to 39.6% (average change of 7.1%) in soybeans. There was a significant correlation between seed yield enhancement and aboveground biomass, seed number, and pod number per plant. At maturity, eCO2 increased seed protein concentration in beans, while it did not affect soybean. Lipid concentration was not affected by eCO2 in either legume species. Compared with ambient CO2 (aCO2), the concentrations of manganese (Mn), iron (Fe), and potassium (K) decreased significantly, magnesium (Mg) increased, while zinc (Zn), phosphorus (P), and calcium (Ca) were not changed under eCO2 in bean seeds. However, in soybean, Mn and K concentrations decreased significantly, Ca increased, and Zn, Fe, P, and Mg concentrations were not significantly affected by eCO2 conditions. Our results suggest that intraspecific variation in seed yield improvement and reduced sensitivity to mineral losses might be suitable parameters for breeders to begin selecting lines that maximize yield and nutrition under eCO2.for breeders to begin selecting lines that maximize yield and nutrition under eCO2.

Biochemical markers to predict internal browning disorders in 'Rocha' pear during storage under high CO2.

BACKGROUND: The aim of this study was to identify biochemical markers to predict internal browning disorders (IBD) in 'Rocha' pear. Fruits from five orchards were stored for 45 days under cold air followed by 100 days in browning-inducing controlled atmosphere (CA) conditions (1 kPa O2 + 10 kPa CO2 ). RESULTS: Relationships between concentrations of ethanol (EtOH), acetaldehyde (AcDH) and ascorbic acid (AA), activities of peroxidase (POX) and polyphenoloxidase (PPO) and IBD incidence were established. The partial least square (PLS) model using the most promising markers, EtOH and AcDH, explained 89% of the variance in IBD incidence, whereas the univariate models based on the same markers explained between 89 and 94%. In contrast, the models based on AA levels and AA depletion rate only explained 57 and 82% of the variance in IBD incidence respectively. Model validation confirmed the robustness of EtOH for the prediction (R2 = 0.91, RMSE = 11.1) and allowed proposing a threshold level of 30 µL EtOH L-1 above which IBD may occur. Using this threshold value, the storage time limit associated with the occurrence of the first IBD symptoms was predicted with an acceptable RMSE of 9 days. CONCLUSION: This work clearly identifies biochemical IBD markers for 'Rocha' pear and shows that dynamic changes in ethanol concentration during the beginning of storage may be used to predict IBD development. Therefore the results presented herein represent a major step forward in the prediction of IBD in 'Rocha' pear. © 2017 Society of Chemical Industry.

Biochemical Basis of CO2-Related Internal Browning Disorders in Pears (Pyrus communis L. cv. Rocha) during Long-Term Storage.

This study aimed at understanding the biochemical basis of internal browning disorders (IBDs) in 'Rocha' pear. For this purpose, the effects of storage under normal controlled atmosphere (CA) (3 kPa of O2 + 0.5 kPa of CO2) and IBD-inducing CA (1 kPa of O2 + 10 kPa of CO2) on the antioxidant and fermentative metabolisms and polyphenol oxidase (PPO) activity and phenolics concentration were studied. The higher IBD incidence in high CO2-stored fruits was positively correlated with fermentative metabolites and negatively with ascorbate and H2O2 concentrations, and it was linked to PPO activation. These results indicate that both the antioxidant and fermentative metabolisms are involved in the occurrence of IBD in 'Rocha' pear. From the integration of the biochemical and enzymatic data, a schematic model illustrating the effects of high CO2 and low O2 in 'Rocha' pears during long-term storage was constructed.

Structure, diffusion, and permeability of protein-stabilized monodispersed oil in water emulsions and their gels: a self-diffusion NMR study.

Self-diffusion NMR is used to investigate monodispersed oil in water emulsions and the subsequent gel formed by removing the water through evaporation. The radius of the oil droplets in the emulsions is measured using a number of diffusion methods based on the measurement of the mean squared displacement of the oil, water, and tracer molecules. The results are consistent with the known size of the emulsions. Bragg-like reflections due to the restricted diffusion of the water around the oil droplets are observed due to the low polydispersity of the emulsions and the dense packing. The resulting data are fitted to a pore glass model to give the diameter of both the pools of interstitial water and the oil droplets. In the gel, information on the residual three-dimensional structure is obtained using the short time behavior of the effective diffusion coefficient to give the surface to volume ratio of the residual protein network structure. The values for the surface to volume ratio are found to be consistent with the expected increase of the surface area of monodisperse droplets forming a gel network. At long diffusion observation times, the permeability of the network structure is investigated by diffusion NMR to give a complete picture of the colloidal system considered.

Design and performance of a high pressure insert for use in a standard magic angle spinning NMR probe.

In this paper we describe the construction and performance of high pressure magic angle inserts made from the polymer PEEK. The inserts were designed to fit inside standard commercial 7 mm magic angle spinning rotors and spin at the maximum frequency of the probe. The sample volume of the inserts was 100 microL. A gas loading chamber that operates at room temperature is described. The performance of the inserts is discussed for a number of gases in terms of resolution as a function of spinning speed and leakage of the gas due to permeation through the polymer. Finally, some preliminary results are shown in relation to complex food materials.