Mode of pancreatic lipase inhibition activity in vitro by some flavonoids and non-flavonoid polyphenols

Numerous reports have shown plant metabolites as potential inhibitors of pancreatic lipase (PL). The most notable group is plant polyphenols. However, a limited number of reports diagnosed their mode of inhibition delineating conflicting results. To elucidate the kinetic mode of PL inhibition, some selected flavonoid and non-flavonoid polyphenol standards were first screened for their lipase inhibition potency by their half maximal inhibitory concentration (IC₅₀) followed by inhibition kinetic analysis. Of the phenolics tested, only gallic acid (GA) and galloyl moiety containing epicatechin, viz., epigallocatechin (EGC) and epigallocatechin gallate (EGCG) showed, comparative to others, higher PL inhibitions (IC₅₀, 387.2, 237.3, and 391.2 μM respectively). Analysis of enzyme inhibition modalities at various substrate concentrations revealed a dose-dependent inhibition of reaction velocity. Inhibitory rates decreased by the order of EGCG > EGC > GA (Ki, 13.29 > 35.0 > 44.61 μM respectively). The results, when verified by visual inspection of Lineweaver–Burk as well as Dixon plots, showed inhibitions of PL by GA, EGC, and EGCG that were best fit to competitive inhibitions. A role of the galloyl moiety in enzyme-inhibitor binding has been evident from their structural resemblance. Depicting it further, ethyl gallate (EG), showed a similar competitive inhibition, therefore, indicating a galloyl moiety driven competitive inhibition of PL.     

Milk enhances intestinal absorption of green tea catechins in in vitro digestion/Caco-2 cells model

The effect of milk on the absorption of polyphenols is still controversial so far. In order to determine the impact of milk addition on green tea catechins bioaccessibility and intestinal absorption an in vitro digestion/Caco-2 cell model was applied. Green tea extract (GTE) was solubilized in distilled water at 23 °C and 100 °C, combined with skimmed milk (GTE + 10% milk and GTE + 25% milk) and subjected to simulated gastric and intestinal digestion, followed by transepithelial absorption in Caco-2 cells monolayers. In the mixture with milk, gallated catechins: ECG and EGCG showed binding to milk proteins while EC and EGC seemed to have weaker affinity. Catechins were stable during gastric incubation and very sensitive to intestinal digestion. Bioaccessibility of green tea catechins brewed at 100 °C was higher than brewed at 23 °C. Catechins from digested GTE with 10% and 25% milk exhibited enhanced intestinal permeability in Caco-2 model in comparison to non-digested GTE and digested GTE without milk. Apparent permeability coefficients (P_app) of EGCG and ECG in digested GTE with 25% milk were significantly higher compared to those in GTE with 10% milk, and amounted to 2.41 × 10^− 6 cm/s and 1.39 × 10^− 6 cm/s. The recoveries of all catechins in GTE with milk in Caco-2 cells after 2 h incubation were significantly higher than that without milk. To summarize, these data suggest that milk addition may increase catechin bioavailability by enhancing their transepithelial absorption and uptake from green tea extract.     

Quality changes of pasteurised mango juice during storage. Part II: Kinetic modelling of the shelf-life markers

The present work shows the potential of the integrated fingerprinting-kinetics approach in evaluating shelf-life changes of pasteurised mango juice (cv. ‘Totapuri’). Seven mango juice formulations (i.e. control (mango puree and water), ascorbic acid-enriched (AA₂₅₀ and AA₅₀₀), citric acid-enriched (CA, CA + AA₂₅₀ and CA + AA₅₀₀) and sugar-enriched (S) samples) were pasteurised and stored at 42 °C for 8 weeks. In this part, the kinetics of the shelf-life markers selected from the multivariate fingerprinting approach was modelled. Changes in selected targeted parameters could be best described by a zero-order (colour values, °Brix, furfural, HMF), a first-order (ascorbic acid), a fractional conversion (fructose, glucose, oxygen) and a second-order model (sucrose). Differences in the rate constant were observed, with faster ascorbic acid degradation and furfural formation in AA-enriched samples and faster hydrolysis of sugars and HMF formation in CA-enriched samples compared to control samples. To describe changes in selected volatiles (terpenes, sulphur compounds, acids, ketones and esters), different kinetic models were selected. Two trends were observed: changes as affected by different mango juice formulations (e.g., faster reaction in CA-enriched samples or in a lower pH condition) and changes irrespective of the formulations. Referring to the literature, in general, acid-catalysed reactions, ascorbic acid degradation and oxidation reactions are the main reactions responsible for the observed quality changes in stored mango juice.     

Quality changes of pasteurised mango juice during storage. Part I: Selecting shelf-life markers by integration of a targeted and untargeted multivariate approach

For the first time, a multivariate approach combining targeted and untargeted data was used to obtain insight into quality changes in pasteurised mango juice (cv. ‘Totapuri’) as a function of storage (42 °C for 8 weeks). Mango juice samples were formulated with addition of different potential precursors for different quality-related chemical reactions: ascorbic acid, citric acid and sugars. Control (diluted mango puree with water), ascorbic acid-enriched (AA₂₅₀ and AA₅₀₀), citric acid-enriched (CA, CA + AA₂₅₀ and CA + AA₅₀₀) and sugar-enriched (S) samples were characterised for a range of targeted quality parameters as well as for a volatile fingerprint (untargeted). Selection of shelf-life markers or quality parameters significantly changing during shelf-life was performed over all formulations as well as per mango juice formulation. Our study showed that a common trend over all formulations was observed for colour values (VID > │0.90│), while specific shelf-life markers were selected for each formulation. In acidified mango juice samples (CA, CA + AA₂₅₀, CA + AA₅₀₀), more terpene oxides were selected compared to other formulations. In ascorbic acid-enriched samples (AA₂₅₀, AA₅₀₀, CA + AA₂₅₀, CA + AA₅₀₀), furfural and ascorbic acid were significantly changing during shelf-life. It seems that the reaction pathways for compounds being formed or degraded upon shelf-life are clearly affected by the acidity level.     

Physical alterations of soybean during accelerated and natural aging

The aim of the present study was to investigate the effect of accelerated aging (AA) and natural aging (NA) on the physical characteristics of soybeans (Glycine max). Soybeans from two cultivars (Coodetec 214 and BRS 267) were stored under AA (30 °C and 84% RH up to nine months), NA (ambient temperature and RH, fluctuation in the period = 17.3 at 24.5 °C and 59 at 93% RH, up to 18 months), and control conditions (− 20 °C and 47% RH). Scanning electron micrographs (SEM) of the hull and cotyledons, the water sorption rate (S) during hydration and equilibrium moisture content (X_eq), the color of the grains and ground soybeans, and the hardness of cooked soybeans were analyzed. After storage of AA and NA, the surface of the palisade cells of the cotyledons became wrinkled and wilted; the browning of the hull, the ground soybeans, and the hardness of the cooked soybeans increased for both cultivars. It was observed that the increase of S and decrease of X_eq were more pronounced in Coodetec 214 than BRS 267.     

Effect of coating and intermittent warming on enzymes,soluble pectin substances and ascorbic acid of Prunus persica (Cv. Zhonghuashoutao) during refrigerated storage

The effect of 1% chitosan coating + polyethylene (PE) package, 1% chitosan + 0.5% CaCl₂ coating + PEpackage, and 1% chitosan + 0.5% CaCl₂ coating + PEpackage + intermittent warming on the enzymes and quality of Zhonghuashoutao fruits (Prunus persica) was studied during refrigerated storage (1 °C). The results showed that, compared to the control (CK) of water dip + PEpackage, all treatments had positive effectiveness on the inhibition of polyphenol oxidase, peroxidase (POD), ascorbic acid oxidases (ASA-POD) and polygalacturonase (PG) activities to some extent, and reduced the increase of soluble pectinefic substance. Results also showed that 1% chitosan + 0.5% CaCl₂ + PEpackage + intermittent warming treatment significantly inhibited ASA-POD and PG activities, kept vitamin C at a high level, and reduced fruit sensitivity to chilling injury at the later stage of storage.     

Inhibition of mackerel (Scomber scombrus) muscle lipoxygenase by green tea polyphenols

The high polyunsaturated fatty acid content of oily fish such as mackerel (Scomber scombrus) makes it particularly susceptible to oxidative degradation. We have shown previously the presence of lipoxygenase (LOX), a lipid oxygenase, in mackerel muscle. In the current study, commercially available green tea polyphenols were shown to effectively inhibit the LOX activity of mackerel muscle. EGCG (epigallocatechin gallate) was the strongest inhibitor tested with an IC₅₀ (concentration for half maximal inhibition) value of 0.13 nM. All the tea catechins showed a mixed non-competitive type inhibition. In addition, antioxidants such as BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), esculetin, caffeic acid, ascorbic acid, and ethylene diamine tetraacetic acid (EDTA) were effective to varying degrees (IC₅₀ values between 0.02 and >50 μM) in the inhibition of mackerel muscle LOX. Nordihydroguaiaretic acid (NDGA), a classical LOX inhibitor and potassium cyanide (KCN), a heme protein inhibitor were assayed for their inhibitory activities for comparison.Post harvest spoilage of fish account for loss of as much as 10% of the world’s catches of cultured fish. This data indicates that the green tea polyphenols, nature’s very potent antioxidants, may be used as an effective and natural means of reducing post harvest spoilage in fish.     

Digestive stability and absorption of green tea polyphenols: Influence of acid and xylitol addition

The objective of this study was to determine the effect of sugar substitute and acid on digestive stability and intestinal uptake of catechins in Ready-To-Drink (RTD) green tea. Green tea extracts formulated with prescribed amounts of sucrose (200, 500, and 1000 mg), glucose (280, 700, and 1400 mg), and xylitol (200, 500, and 1000 mg) in combination with citric acid (10 mg) or vitamin C (10 mg) were subjected to an in vitro digestion model coupled with Caco-2 cells. Green tea extracts only showed a poor digestive recovery (5.3%) of total catechins and EGC and EGCG significantly decreased with the digestive recovery of 4.6% and 6.1%, respectively. However, measured amount of EGC, EGCG, or ECG in digestive fluids and caco-2 human intestinal cell significantly increased by adding citric acid or vitamin C. There was remarkable increase of digestive recovery of total catechins in green tea with xylitol/citric acid and xylitol/vitamin C by 1.7–2.5 times and 3 times, respectively, with different amounts of xylitol. It was also determined that intestinal uptake of total catechins significantly increased 6 and 11 times in green tea with xylitol/citric acid and xylitol/vitamin C, respectively, compared to green tea only.     

High molecular weight persimmon tannin is a potent antioxidant both ex vivo and in vivo

The antioxidant activities of high molecular weight persimmon condensed tannin (HMWPT) were evaluated in an ex vivo tissue system and in vivo. Addition of HMWPT to mouse liver homogenate protected the samples against auto-peroxidation or H₂O₂- or Fe²⁺/ascorbic acid-induced lipid peroxidation. The IC₅₀ values for HMWPT were 4.32 ± 0.20 μg/mL (auto-oxidation), 1.36 ± 0.40 μg/mL (H₂O₂-induced peroxidation) or 0.20 ± 0.09 mg/mL (Fe²⁺/ascorbic acid-induced peroxidation). Mice were oxidatively stressed with bromobenzene to test the antioxidant activity of HMWPT in vivo. An oral dose of HMWPT at 200 or 400 mg/kg HMWPT significantly (P < 0.01) prevented the bromobenzene-induced decrease in serum and liver superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities, and decreased liver malondialdehyde levels in bromobenzene-treated mice (P < 0.01). The results suggest that dietary HMWPT may provide protection from oxidative damage both ex vivo and in vivo.     

Effect of a prestorage treatment with 6-benzylaminopurine and modified atmosphere packaging storage on the respiration and quality of green asparagus spears

Fresh green asparagus (Asparagus officinalis L.) spears were subjected to a prestorage treatment by dipping in 20 ppm 6-benzylaminopurine (6-BA) for 10 min. Treated and untreated spears were placed into low-density polyethylene (LDPE) bags with a thickness of 15 μm, in which a passive modification of the atmosphere was developed, or 25 μm, in which a gas mixture of 10 kPa O₂ + 5 kPa CO₂ was flushed and then the bags were stored for 24 days at 2 °C. Atmosphere composition, chlorophyll, ascorbic acid, fiber, color and sensory attributes were determined every 4 days. Throughout the storage period, O₂ level decreased from the initial values (21 kPa, 10 kPa) to 2.1–4.2 kPa in package without 6-BA treatment and to 4.9–6.8 kPa in package with 6-BA treatment. CO₂ level increased from the initial value (0 kPa, 5 kPa) to 5.5–7.2 kPa in packages without 6-BA treatment and to 4.1–6.1 kPa in packages with 6-BA treatment. In both packaging treatments, at the end of the 24 day storage period, the spears treated with 6-BA had a better color, firmness and overall appearance; moreover they retained more chlorophyll and ascorbic acid and they had less fiber.     

Rheological study of giant squid surimi (Dosidicus gigas) made by two methods with different cryoprotectants added

Two new methods were designed for making surimi from giant squid (Dosidicus gigas) muscle. The first is based on protein precipitation at the isoelectric point (type A), and the second on washing with an acid solution (type B). Chemical analyses (e.g. protein solubility, electrophoretic profile), structural analyses (scanning electronic microscopy) and above all rheological analyses were carried out. Small amplitude oscillatory tests were performed to evaluate the influence of these two methods on the viscoelasticity and gel-forming ability of squid surimi. The results showed that method B preserves the functionality of the myofibrillar proteins better, thus making for a better gel structure than method A. Moreover, the addition of different cryoprotectants (sorbitol + sucrose, sorbitol + trehalose, trehalose alone), resulted in essential differences between the two kinds of surimi. In surimi A, trehalose favoured less initial protein aggregation and hence a thermorheologically stable structure, with a better gelation profile than sorbitol + sucrose or sorbitol + trehalose, in surimi, suwari-gels and definitive-gels alike. However, in B samples the influence of different cryoprotectants was not discernible.     

Improved in vitro digestion stability of (−)-epigallocatechin gallate through nanoliposome encapsulation

(−)-Epigallocatechin gallate (EGCG) is unstable and degraded in near-neutral or alkaline fluids. To overcome its limitation, EGCG nanoliposome (EN) was prepared by an ethanol injection method combined with dynamic high-pressure microfluidization. EN possessed good physicochemical characterizations (high entrapment efficiency = 92.1%, small average particle size = 71.7 nm, low polydispersity index = 0.286 and zeta potential = − 10.81 mv). EN exhibited a relative good sustained release property. Stability of EGCG in simulated intestinal fluid (SIF) was significantly improved by nanoliposome encapsulation. After 1.5 h incubating in SIF without or with pancreatin, the residual EGCG of EN was 31.2% and 47.7% respectively, but the residual EGCG in EGCG solution was only 3.4% and 3.5% respectively. The degenerations of in vitro antioxidant activities of EGCG were effectively slowed by nanoliposome encapsulation. This study expects to provide theories and practice guides for further applications of EN.     

Osmotic dehydration of carrot tissue enhanced by pulsed electric field,salt and centrifugal force

The osmotic dehydration (OD) kinetics of carrot disc untreated and treated by pulsed electric field (PEF) was studied under centrifugation (2400 × g), stirring (250 rpm) and with a salt addition (NaCl/sucrose solutions 0%/65%, 5%/60% and 15%/50%). The PEF intensity was E = 0.60 kV/cm and the treatment duration was t_PEF = 0.05 s (500 rectangular monopolar pulses each of 100 μs). The water loss (WL), solids gain (SG) and water loss/solids gain ratios (WL/SG) were evaluated in the binary (sucrose + water) and ternary (sucrose + salt + water) solutions at the temperature of 20 °C during 4 h. The mass ratio of sample to solution was 1:3. The PEF treatment and salt addition enhanced the OD kinetics. WL and SG were increased under centrifugation (centrifugal OD) and under stirring (static OD). The centrifugal field enhanced the WL, however, decreased the SG comparing to the static OD. Therefore, the static OD has advantages for the higher SG (confectionary adds), while the centrifugal OD is better appropriated if the WL should be increased and the solids (sugar) uptake should be limited (dietetic products).The two-exponential kinetic model fitted well to experimental data for both static and centrifugal OD. The correlation coefficient was R² = 0.982–0.999 and the standard error was 5–10%.     

Packaging-specific influence of chitosan on color stability and lipid oxidation in refrigerated ground beef

We examined the influence of chitosan on lipid oxidation and color stability of ground beef stored in different modified atmosphere packaging (MAP) systems. Ground beef patties with chitosan (1%) or without chitosan (control) were packaged either in high-oxygen MAP (HIOX; 80% O₂ + 20% CO₂), carbon monoxide MAP (CO; 0.4% CO + 19.6% CO₂ + 80% N₂), vacuum (VP), or aerobic packaging (PVC) and stored at 1 °C. Chitosan increased (P < 0.05) redness of patties stored in PVC and CO, whereas it had no effect (P > 0.05) in HIOX. Chitosan patties demonstrated lower (P < 0.05) lipid oxidation than controls in all packaging. Control patties in PVC and HIOX exhibited greater (P < 0.05) lipid oxidation than those in VP and CO, whereas chitosan patties in different packaging systems were not different (P > 0.05) from each other. Our findings suggested that antioxidant effects of chitosan on ground beef are packaging-specific.     

Lipase-catalyzed synthesis of acetylated EGCG and antioxidant properties of the acetylated derivatives

(−)-Epigallocatechin-3-O-gallate (EGCG) acetylated derivatives were prepared by lipase catalyzed acylation of EGCG with vinyl acetate to improve its lipophilicity and expand its application in lipophilic media. The immobilized lipase, Lipozyme RM IM, was found to be the optimum catalyst. The optimized conditions were as follows, 1:1 of the molar ratio of EGCG to vinyl acetate, 2.0% (w/w of both substrates) of enzyme amount, and 84.5% conversion was obtained after 8 h reaction at 40 °C in acetonitrile. The presence of mono-, di- and tri-acetylated derivatives in acetylated EGCG were confirmed by LC–MS–MS and the tri-acetylated EGCG was identified as 5′,3″,5″-3-O-acetyl-EGCG by NMR. Their enhanced lipophilicity was confirmed by octanol–water partition coefficient. The antioxidant activity of the acetylated EGCG derivatives were superior to butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ) and EGCG as determined by peroxide values (POVs) in sunflower oil as well as by the p-anisidine method. Acetylated EGCG exhibited the highest 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (IC₅₀ of 0.09 mg/mL) compared to EGCG, BHT and TBHQ. Acetylated EGCG might be used as a potent antioxidant for controlling oxidation of sunflower oil.     

Chemical composition of wild edible mushrooms and antioxidant properties of their water soluble polysaccharidic and ethanolic fractions

Mushrooms have become attractive as functional foods and as a source of physiologically beneficial bioactive compounds. Herein, we describe and compare the chemical constituents (phenolic compounds, macronutrients, sugars, fatty acids, tocopherols and ascorbic acid) of four wild edible mushrooms widely appreciated in gastronomy: Armillaria mellea (Vahl) P. Kumm., Calocybe gambosa (Fr.) Donk, Clitocybe odora (Fr.) P. Kumm., Coprinus comatus (O.F. Müll.) Pers. Furthermore, the antioxidant activity of their water soluble polysaccharidic and ethanolic fractions was studied by three different in vitro assays. C. comatus revealed the highest concentrations of sugars (43.23/100 g dry weight), PUFA (77.46%), phenolic compounds (45.02 mg/kg), tocopherols (301.03 μg/100 g) and, among all of the fractions tested, its ethanolic fraction showed the highest antioxidant activity (EC₅₀ < 2.6 mg/ml). C. odora revealed one of the highest ascorbic acid (172.65 mg/100 g) contents and its water soluble polysaccharidic fraction showed the best antioxidant properties (EC₅₀ < 3.6 mg/ml) among the polysaccharidic fractions. The studied mushrooms species could potentially be used in well-balanced diets and as a source of bioactive compounds.     

Decontamination of Salmonella enterica Typhimurium on green onions using a new formula of sanitizer washing and pulsed UV light (PL)

Pathogenic bacteria such as Salmonella and Shigella flexneri have been linked to green onion contamination. This study was conducted to evaluate decontamination of Salmonella Typhimurium using a new formula of sanitizer washing (0.4 mg/mL thymol and five new formula sanitizers including 300 ppm H₂O₂ + 4% SDS, 2 mg/mL citric acid + 4% SDS, 0.2 mg/mL thymol + 4% SDS, 0.2 mg/mL thymol + 2 mg/mL citric acid and 0.2 mg/mL thymol + 2 mg/mL acetic acid), pulsed UV light (PL) as well as synergy between the sanitizer wash and PL. New formula sanitizers based on decontamination efficacy of single washing solutions (organic acids, hydrogen peroxide (H₂O₂), essential oil or surfactant) were applied to decontaminate spot inoculated green onions. PL, the novel technique, alone has been applied to inactivate Salmonella on both dip and spot inoculated green onions. Salmonella inactivation of PL–new formula sanitizer combinations on dip inoculated green onions was investigated for their potential synergy. As a result, for spot inoculated green onions, 0.4 mg/mL thymol individually and the five new formula sanitizers all achieved higher log reduction of Salmonella (4.5–5.3 log 10 CFU/g reduction) than the 200 ppm chlorine washing. These new formulas of sanitizer would be potential alternatives to chlorine. The 5 s dry PL (4.6 log 10 CFU/g) or 60 s wet PL treatment (3.6 log 10 CFU/g) was better or comparable as chlorine washing. The sanitizer combinations did not provide significantly higher log reduction than PL, and PL has the potential of being used in the green onion industry for decontamination purpose. For dip inoculated green onions, none of our treatment provided > 0.8 log 10 CFU/g (0.6–0.8 log 10 CFU/g) reduction of Salmonella. As a result, the PL–new formula sanitizer combinations had no or minimal synergy to inactivate Salmonella dip inoculated on green onions.     

Mastication effects on carotenoid bioaccessibility from mango fruit tissue

The release of carotenoids from fresh fruits or vegetables is determined by the encapsulating plant tissue matrix, intracellular carotenoid location within the cell, and the mastication process. The objectives of this study were to assess the particle sizes obtained after mastication of mango fruit tissue, and how the resulting degree of plant tissue rupture affects carotenoid bioaccessibility. A fine and a coarse chewer were selected after screening 20 healthy volunteers for in vivo human mastication, and the collected chewed boluses were subjected to wet sieving fractionation, followed by an in vitro gastric and small intestinal digestion model. Confocal micrographs show that the smallest particle size fraction (0.075 mm) consists mostly of fragmented cells and the largest size fraction (2.8 mm) contains bulky clusters of whole cells and vascular fibers. Higher amounts of total carotenoids (211–320 μg/100 g) were observed in the larger particle size fraction (2.8 mm) relative to the 1 mm (192–249 μg/100 g) and 0.075 mm fractions (136–199 μg/100 g). Smaller particles showed a greater % release of total carotenoids after in vitro digestion. Xanthophyll derivatives are more bioaccessible than β-carotene for all particle sizes. The effects of particle size or degree of fine vs coarse chewing are unexpectedly small (p > 0.05), but the process of chewing substantially reduced the release of β-carotene and xanthophylls by 34% and 18%, respectively. While there is a (small) particle size effect, this appears to not be the primary factor controlling bioaccessibility for soft tissues such as mango, in contrast to previous reports that a single cell wall appears to be enough to prevent bioaccessibility of carotenoids in more robust carrot tissues.     

Effect of chill storage and modified atmosphere packaging (MAP) on antioxidant activity,anthocyanins, carotenoids,phenolics and sensory quality of ready-to-eat shredded orange and purple carrots

Ready-to-eat shredded orange and purple carrots, packed in air (control), or in modified atmosphere packaging [MAP; (90%N₂ + 5%O₂ + 5%CO₂ and 95%O₂ + 5%CO₂)], and stored chilled for up to 13 days, were examined for their antioxidant activity and contents of anthocyanins, carotenoids and phenolics, as well as sensory quality. Total antioxidant activity, carotenoids and phenolics of purple carrots were initially 2.8-, 2.3- and 2.9-fold higher than orange carrots, respectively. Total antioxidant activity remained relatively constant in orange carrots during storage under all treatment conditions, whereas a highly significant decrease (P<0.01) in (95%O₂ + 5%CO₂)-treated purple carrots was observed. The content of anthocyanin, only found in purple carrots, was decreased slightly during the storage period, and this was particularly significant in the 95%O₂ + 5%CO₂ treatment. In both orange and purple carrots, loss of total carotenoids occurred in the 95%O₂ + 5%CO₂ treatment. Total phenolic content of purple carrots increased at a much higher rate during storage than orange carrots. The MAP treatment (90%N₂ + 5%O₂ + 5%CO₂) gave better sensory quality and extended shelf-life for purple carrots (∼2–3 days longer shelf-life than other treatments,) but, no difference was observed for orange carrots. Shredded purple carrot can be stored under 90%N₂ + 5%CO₂ + 5%O₂ treatment for up to 10 days and high nitrogen treatment may be used in maintaining the storage quality of shredded purple carrots. Thus, purple carrots may be used in place of orange carrots to take advantage of their nutraceutical components.     

Fat contributes to the buffering capacity of chicken skin and meat but enhances the vulnerability of attached Salmonella cells to acetic acid treatment

Chicken skin and chicken meat display different buffering effects which may impact the survival of Salmonella attached to them when treated with acids. This study investigated the role that differences in fat composition of chicken skin and meat play in their buffering capacity. The survival of Salmonella attached to chicken skin and meat in the presence of fat, and treated with acetic acid was also investigated. Fat was extracted from chicken skin and meat and the buffering capacities of chicken skin, meat, extracted fat and their respective remnants were determined. Two strains of Salmonella Typhimurium and two strains of S. Enteritidis were attached independently to each of the chicken component listed above and enumerated before and after treatment with 0.3 M acetic acid. Chicken skin has a higher fat content as compared to chicken meat. Skin (13 mmol H⁺/(pH1 kg)) had a stronger buffering capacity (p < 0.05) than the extracted fat alone and skin remnants alone (7.0 mmol H⁺/(pH 1 kg) and 6.9 mmol H⁺/(pH 1 kg) respectively). From an initial inoculum (~ 9 log CFU/g), Salmonella cells attached better (p < 0.05) to chicken meat (~ 8 log CFU/g) and chicken skin (~ 7 log CFU/g) than extracted fat (~ 1.5 log CFU/g). Skin remnants without fat were better (p < 0.05) at protecting attached Salmonella than other chicken components. For example S. Typhimurium ATCC 33062 decreased ~ 1 log CFU/g (p < 0.05) on skin remnants after acetic acid treatment while its viable counts on other components decreased from ~ 1.5 to 7 log CFU/g (p < 0.05). We suggest that the fat content present in the skin may enhance the vulnerability of attached cells to acetic acid.