Unsaturated fat fraction from lard increases the oxidative stability of minced pork

Abstract Lard from pork back fat was dry fractionated based on crystallization temperature, resulting in fractions with a ratio of saturated to unsaturated fatty acids of 1.10 and 0.61. Lean minced pork was mixed with the saturated and unsaturated fat fraction and stored in modified atmosphere (80% O2 and 20% CO2) at 5 °C for 2, 5, 7, 9, and 12 days under light to investigate the effect on oxidative stability of lipids and proteins. The saturated fat group developed higher TBARS values and lower levels of free thiol groups during storage, indicating that the unsaturated fat fraction in minced pork promoted increased oxidative stability of both lipids and proteins. A higher content of α-tocopherol in the unsaturated fat fraction suggests that the differences in oxidative stability is causatively linked to the balance between the fatty acid composition and content of antioxidants. The TBARS values and free thiol content were negatively correlated, suggesting a relationship between lipid and protein oxidation.Peer reviewe

Lipid-modifying enzymes in oat and faba bean

The aim was to study lipase, lipoxygenase (LOX) and peroxygenase (PDX) activities in oat and faba bean samples to be able to evaluate their potential in formation of lipid-derived off-flavours. Lipase and LOX activities were measured by spectroscopy, and PDX activities via the formation of epoxides. An ultra-high performance liquid chromatography method was developed to study the formation of fatty acid epoxides. The epoxides of esters were measured by gas chromatography. Mass spectroscopy was used to verify the identity of the epoxides. Both oat and faba bean possessed high lipase activities. In faba bean, LOX catalysed the formation of hydroperoxides, whose break-down products are the likely cause of off-flavours. Since oat had low LOX activity, autoxidation is needed to initiate lipid oxidation. Oat had high PDX activity, which is able to convert hydroperoxides to epoxy and hydroxy fatty acids that could contribute significantly to off-flavours. PDX activity in the faba bean was low. Thus, in faba bean volatile lipid oxidation products could rapidly be formed by LOX, whereas in oat reactions are slower due to the need of autoxidation prior to further reactions.Peer reviewe

Potential of faba bean lipase and lipoxygenase to promote formation of volatile lipid oxidation products in food models

Faba bean can respond to the need for plant-based proteins for human consumption. The aim of this work was to study the role of lipid-modifying enzymes in faba bean in causing off-flavour compounds during processing. The faba bean exhibited high lipase and lipoxygenase (LOX) activities, with pH optima being 8.0 and 6.0, respectively. Faba bean LOX preferred free fatty acids (FFAs) over triacylglycerols as substrates, and together with other LOX pathway enzymes, it formed specific volatile products, as measured using headspace solid-phase microextraction-gas chromatography. During the preparation of the food models (i.e. the extracts and emulsions), enzymatic lipid oxidation occurred. The inclusion in the emulsions of rapeseed oil, especially of rapeseed oil FFAs, remarkably increased the amounts of volatile products. The largest quantities of products were formed in food models at pH 6.4, which is close to the pH optimum of LOX. Further studies on lipase in food models are needed.Peer reviewe

The Impact of Vanilla and Lemon Aromas on Sensory Perception in Plant-Based Yogurts Measured with Static and Dynamic Methods

The application of cross-modal interaction is a potential strategy to tackle the challenges related to poor sensory properties, such as thin mouthfeel, in plant-based yogurts. Thus, we aim to study the influence of aroma compounds possibly congruent with sweetness on the perceived sensory profile. Descriptive analysis and temporal dominance of sensations (n = 10 × 4) with a trained panel were conducted with and without a nose clip. One unflavored sample and samples flavored with either lemon or vanilla aromas were included (vanilla; 0.05%; 0.1%; lemon: 0.025%; 0.05%). Odor intensity, thick, sticky, and melting sensation, sweetness, and grain-like flavor were evaluated on an unstructured 10-cm line scale with anchors and reference samples. The results demonstrate how vanilla and lemon aromas suppressed grain-like flavor and enhanced odor intensity and sweetness. The following order was detected among samples in perceived sweetness intensity: unflavored < lemon < vanilla. The two sessions with and without nose clip differed statistically in sweetness, highlighting that the aromas impacted the perceived sweetness but not the mouthfeel in vanilla samples. The study suggests that congruent aromas could modify the perceived sweetness in plant-based yogurts; however, aroma or perceived sweetness does not impact the mouthfeel in plant-based yogurts. While the odor–taste interaction in such products is evident, the study highlights that aroma compounds alone do not modify mouthfeel

The Impact of Vanilla and Lemon Aromas on Sensory Perception in Plant-Based Yogurts Measured with Static and Dynamic Methods

The application of cross-modal interaction is a potential strategy to tackle the challenges related to poor sensory properties, such as thin mouthfeel, in plant-based yogurts. Thus, we aim to study the influence of aroma compounds possibly congruent with sweetness on the perceived sensory profile. Descriptive analysis and temporal dominance of sensations (n = 10 × 4) with a trained panel were conducted with and without a nose clip. One unflavored sample and samples flavored with either lemon or vanilla aromas were included (vanilla; 0.05%; 0.1%; lemon: 0.025%; 0.05%). Odor intensity, thick, sticky, and melting sensation, sweetness, and grain-like flavor were evaluated on an unstructured 10-cm line scale with anchors and reference samples. The results demonstrate how vanilla and lemon aromas suppressed grain-like flavor and enhanced odor intensity and sweetness. The following order was detected among samples in perceived sweetness intensity: unflavored < lemon < vanilla. The two sessions with and without nose clip differed statistically in sweetness, highlighting that the aromas impacted the perceived sweetness but not the mouthfeel in vanilla samples. The study suggests that congruent aromas could modify the perceived sweetness in plant-based yogurts; however, aroma or perceived sweetness does not impact the mouthfeel in plant-based yogurts. While the odor–taste interaction in such products is evident, the study highlights that aroma compounds alone do not modify mouthfeel

Fermentation Conditions Affect the Synthesis of Volatile Compounds, Dextran, and Organic Acids by Weissella confusa A16 in Faba Bean Protein Concentrate

Fermentation with Weissella confusa A16 could improve the flavor of various plant-based sources. However, less is known about the influence of fermentation conditions on the profile of volatile compounds, dextran synthesis and acidity. The present work investigates the synthesis of potential flavor-active volatile compounds, dextran, acetic acid, and lactic acid, as well as the changes in viscosity, pH, and total titratable acidity, during fermentation of faba bean protein concentrate with W. confusa A16. A Response Surface Methodology was applied to study the effect of time, temperature, dough yield, and inoculum ratio on the aforementioned responses. Twenty-nine fermentations were carried out using a Central Composite Face design. A total of 39 volatile organic compounds were identified: 2 organic acids, 7 alcohols, 8 aldehydes, 2 alkanes, 12 esters, 3 ketones, 2 aromatic compounds, and 3 terpenes. Long fermentation time and high temperature caused the formation of ethanol and ethyl acetate and the reduction of hexanal, among other compounds linked to the beany flavor. Levels of dextran, acetic acid, and lactic acid increased with increasing temperature, time, and dough yield. Optimal points set for increased dextran and reduced acidity were found at low temperatures and high dough yield. Such conditions would result in hexanal, ethyl acetate and ethanol having a relative peak area of 35.9%, 7.4%, and 4.9%, respectively

Addressing criticalities in the INFOGEST static in vitro digestion protocol for oleogel analysis

The interest on the digestive fate of oleogels, i.e., substitutes for solid fats rich in liquid oil, have pushed re-searchers to use the widely adopted INFOGEST protocol for static in vitro digestion. However, this protocol was originally designed to simulate the digestibility of conventional foods and to accommodate the large fraction of oil in oleogels, researchers have deliberately modified the INFOGEST protocol, inadvertently leading to results difficult to be compared. In this study, we highlighted possible problems that may arise during oleogel simulated digestion such as under-or overestimation of oleogel lipolysis. The effect of oleogel amount, oleogelator type and concentration, and shear applied during digestion on the rate and extent of oleogel digestion was studied. The release of fatty acids during the application of INFOGEST protocol was monitored using the pH-stat method and compared to those analyzed by HPLC-ELSD. Oleogels' structural information was obtained using brightfield, polarized, and fluorescence microscopy, and DSC. We determined that lipolysis of ethylcellulose oleogels follow the "interaction with enzymes and bile salts " pattern, whereas that of wax oleogels follow the "disintegration of oleogel and interaction with enzymes and bile salts ". We also observed that the chemical composition of wax, crystal morphology, and crystal distribution do not alter the lipolysis of oil entrapped inside the wax crystals. We finally recommended a few minimal but fundamental modifications to the INFOGEST protocol to achieve more reliable results from the static in vitro digestion of oleogels and possibly other lipid-based systems.Peer reviewe

Determination of non-polar and mid-polar monomeric oxidation products of stigmasterol during thermo-oxidation

Oxidation products of stigmasterol were characterised by their polarity and molecular size using solid phase extraction (SPE) and high-performance size exclusion chromatography (HPSEC) methods. Monomeric oxides were studied further by GC–MS and GC–FID. The focus was on identifying and quantifying non-polar and mid-polar monomeric oxides after SPE fractionation. Commercial stigmasterol was subjected to 180 °C up to 3 h. Six oxidation products were identified by GC–MS in the non-polar and mid-polar monomeric fractions; all appeared during the first hour of heating. Quantification by GC–FID showed an increase in the non-polar and mid-polar oxidation products during the heating time, and their amounts reached values of 6.1 and 47.0 g/kg of commercial stigmasterol, respectively. Polar oxidation products commonly measured reached a value of 193 g/kg after 1 h of heating, while after 3 h of heating their concentration was only 164 g/kg. Since as much as 550 g/kg of stigmasterol was decomposed, the monomeric products explained only partly the stigmasterol loss. Dimeric and polymeric products contributed to 165 g/kg of the loss showing the importance of polymerisation reactions at 180 °C