Efficacy of plant essential oils as antimicrobial agents against Listeria monocytogenes in hotdogs

The purpose of this study was to evaluate the antimicrobial activity of different plant essential oils against Listeria monocytogenes, both in vitro and in a food system. Essential oils of thyme, clove, and pimenta were found to be most effective, based on disc diffusion experiments. Thyme and clove proved to be highly effective against L. monocytogenes in peptone water (1 g/l) and reduced the bacterial population below detection limits at concentrations of 1 ml/l. Experiments were also carried out in hotdogs of different fat content (zero-, low-, and full-fat) to evaluate the antimicrobial activity of essential oils against L. monocytogenes. Thyme essential oil reduced bacterial populations significantly (P⩽0.05) at 1 ml/l level in zero- and low-fat hotdogs, but not in full-fat hotdogs. At 10 ml/l level it reduced the bacterial population >1.3 log₁₀ cfu/g in zero-fat hotdogs, but was less effective in low- and full-fat hotdogs. Clove essential oil also exhibited antimicrobial activity at 1 ml/l in all hotdogs, and was more effective than thyme at 5 ml/l. However, increasing concentration to 10 ml/l did not result in significant (P⩽0.05) reduction of bacterial population. It is concluded that efficacy of essential oils was reduced in a food system due to interaction with food components.     

Antioxidant and antibacterial effects of Lavandula and Mentha essential oils in minced beef inoculated with E. coli O157:H7 and S. aureus during storage at abuse refrigeration temperature

The essential oils (EOs) of Lavandula angustifolia L. and Mentha piperita L. were analyzed by gas chromatography mass spectrometry (GC/MS). The major constituents were linalool (22.35%), linalyl acetate (21.80%), trans-ocimene (6.16%) and 4-terpineol (5.19%) for L. angustifolia and menthol (33.28%), menthone (22.03%), and menthyl acetate (6.40%) for M. piperita.In vitro antibacterial activity of both EOs against Escherichia coli O157:H7 and Staphylococcus aureus CECT 4459 showed high inhibition against S. aureus. The lowest minimal inhibitory concentrations (MIC) were obtained with L. angustifolia (0.25 μL/mL) against S. aureus; M. piperita exhibited a MIC of 0.50 μL/mL against both microorganisms. Both EOs caused a significant decrease of bacterial growth in minced beef (p < 0.05) stored at 9 ± 1 °C. Minced beef treated with EOs showed the lowest TBARS values (lipid oxidation). Moreover, the results showed that the addition of EOs significantly extended fresh meat odor even at abuse temperature.     

Purification and characterization of angiotensin I-converting enzyme inhibitory peptides of small red bean (Phaseolus vulgaris) hydrolysates

Angiotensin I-converting enzyme (ACE) inhibitory activity was investigated for small red bean (Phaseolus vulgaris) protein hydrolysate produced by sequential digestion of Alcalase, papain followed by in vitro gastrointestinal simulation. The hydrolysate had ACE inhibitory activity with IC₅₀ of 67.2 ± 1.8 μg protein/mL. Peptides responsible for potent ACE inhibitory activity were isolated by a three-step purification process, including ultrafiltration, gel filtration and preparative reverse phase high performance chromatography (RP-HPLC). The fraction obtained after RP-HPLC fractionation with the highest activity yielded an IC₅₀ of 19.3 ± 1.4 μg protein/mL. Enzymatic kinetic studies using this fraction demonstrated competitive inhibition with K_i of 11.6 ± 1.7 μg protein/mL. Mass spectrometric characterization identified for the first time the octapeptide PVNNPQIH which demonstrated an IC₅₀ value of 206.7 ± 3.9 μM. The results expand the knowledge base of ACE inhibitory properties of small red bean protein hydrolysate and should be useful in further identification of specific ACE inhibitory peptides in beans.     

Antimicrobial and antioxidant activity of essential oil from pink pepper tree (Schinus terebinthifolius Raddi) in vitro and in cheese experimentally contaminated with Listeria monocytogenes

Natural compounds with preservative activity have gained prominence in the field of food science as an alternative to traditional additives. To be effective, biopreservatives must have antioxidant and/or antimicrobial activities, characteristics often found in the essential oils (EO). This study aimed to verify the antimicrobial and antioxidant activity of EO from pink pepper tree fruit. Antimicrobial activity was evaluated in vitro on 18 bacteria, and in situ (Minas-type fresh cheese) against Listeria monocytogenes during storage (30 days/4 °C). The EO from ripe fruit showed the greatest activity in in vitro tests (MBC of 6.8 mg/mL for L. monocytogenes) and exhibited biopreservative activity in situ, having reduced the development of L. monocytogenes by 1.3 log CFU/g in 30 days. The values of peroxides and malonaldehydes were reduced by 3 Meq O₂/Kg and 0.15 mg MDA/Kg, respectively, in 30 days. Results demonstrate that this EO has the potential to act as a preservative in food.Industrial relevanceThe pink pepper tree (Schinus terebinthifolius Raddi) is a plant with favorable features for industrial use, but little exploited by the food industry so far. In this work, the essential oil (EO) of the pink pepper tree was presented as an alternative to us of preservatives traditionally applied in food. For this, antimicrobial and antioxidant activities of the EO were evaluated and discussed, analyzing its effects initially in vitro and after in situ, in order to infer the technological potential for application this extract may have use as a food biopreservative.     

In vitro antioxidant study of vegetable oils containing conjugated linolenic acid isomers

The study aimed to evaluate the antioxidant activity (in vitro) of vegetable oils containing conjugated linolenic acid (CLnA) isomers such as α-eleostearic and punicic acid and also to evaluate the comparative effectiveness of these vegetable oils due to presence of cis–trans isomers in variable amount. Different in vitro methods were used to evaluate the free radical scavenging activity, hydroxyl radical scavenging activity, metal chelating activity and reducing activity of oils at different concentrations of CLnA isomers such as 125, 250 and 375 μg/mL. Inhibition on lipid peroxidation was evaluated by measuring thiobarbituric acid responsive substance (TBARS) and conjugated diene formation at 125 and 250 μg/mL concentrations of CLnA. Both the oils showed potent free radical scavenging activity at 375 μg/mL concentration. In contrary, these oils showed higher hydroxyl radical scavenging, metal chelation and reducing activity at lower concentration i.e. 125 μg/mL. TBARS formation and conjugated diene formation was lower i.e. inhibition of lipid peroxidation was maximum at 125 μg/mL of both CLnA isomers. Overall, both the oils showed better antioxidant activity at lower concentration due to better oxidative stability and bitter gourd oil showed more prominent antioxidant activity than snake gourd oil due to presence of higher trans content.     

Angiotensin I-converting enzyme inhibitory activity of chickpea and pea protein hydrolysates

ACE inhibitory activity was studied for different hydrolysates obtained from protein concentrates of chickpea (kabuli and desi) and yellow pea (Golden) using in vitro gastrointestinal simulation, alcalase/flavourzyme, and papain. Protein/peptide profiles studied by SDS–PAGE and SE-HPLC, showed a rich composition of the hydrolysates in small peptides having MWs under 4 kDa. Papain hydrolysed yellow pea proteins showed the highest ACE inhibitory activity. In addition, chickpea desi proteins hydrolysed by in vitro gastrointestinal simulation showed higher ACE inhibition (IC₅₀ of 140 ± 1 μg/ml) compared to its digests obtained by alcalase/flavourzyme (IC₅₀ of 228 ± 3 μg/ml) or papain (IC₅₀ of 180 ± 1 μg/ml) and to chickpea kabuli hydrolysed by gastrointestinal simulation (IC₅₀ of 229 ± 1 μg/ml). The results demonstrate that enzymatic hydrolysates of chickpea and pea proteins contain bioactive ACE inhibitory peptides; furthermore, the type of enzyme used for hydrolysis affects the ACE inhibitory activity.     

Nanoencapsulation of Zataria multiflora essential oil preparation and characterization with enhanced antifungal activity for controlling Botrytis cinerea,the causal agent of gray mould disease

This study was undertaken to investigate the nanoencapsulation of Zataria multiflora essential oil (ZEO) in chitosan nanoparticles (CSNPs) in order to enhance antifungal activity and stability of the oils against one isolate of Botrytis cinerea Pers., the causal agent of gray mould disease. ZEO was encapsulated by an ionic gelation technique into CSNPs with an average size of 125–175 nm as observed by transmission electron microscopy (TEM). From UV-vis spectrophotometry results, the drug encapsulation and loading efficiency of ZEO decreased from 45.24% to 3.26% and from 9.05% to 5.22%, respectively, upon increasing initial ZEO content from 0.25 to 1 g/g chitosan. In vitro release studies also demonstrated a controlled and sustained release of ZEO for 40 days. The superior performance of ZEO when encapsulated by CSNPs under both in vitro and in vivo conditions in comparison with unmodified ZEO against B. cinerea was revealed. The in vivo experiment also showed that the encapsulated oils at 1500 ppm concentration significantly decreased both disease severity and incidence of Botrytis-inoculated strawberries during 7 days of storage at 4 °C followed by 2–3 more days at 20 °C. These findings revealed the promising role of CSNPs as a controlled release system for EOs in order to enhance antifungal activities.Industrial relevance: Application of plant essential oil (EOs) treatment at pre- or postharvest stage has been considered as an alternative treatment to the use of synthetic fungicides to prevent fruit postharvest decay and to extend the storage life while retaining the overall quality of different fresh commodities. Although EOs have proved to be good antimicrobial agents, their use for maintaining fruit quality and reducing fungal decay is often limited due to their volatile compounds which can easily suffer degradation under the action of heat, pressure, light and oxygen. Furthermore, they are insoluble in water, and for certain applications a controlled release is required. In this regard, nano-size carriers provide more surface area and can possibly upgrade solubility, enhance bioavailability and improve controlled release and targeting of the encapsulated food ingredients, in comparison to micro-size carriers. These findings revealed the promising role of CSNPs as a controlled release system for EOs in order to enhance their antimicrobial activities.     

Evaluation and improvement of antioxidant and antibacterial activities of supercritical extracts from clove buds

For the first time, extracts from clove buds obtained by supercritical carbon dioxide extraction were screened for antioxidant and antibacterial activities. Additionally, antioxidant and antibacterial activities of extracts obtained by the supercritical extraction of the clove bud–oregano leaf mixtures were studied. Supercritical extract of pure clove had the highest eugenol (64%) and total phenolic content (530.56 mg GAE/g_extract). All extracts had antioxidant activity comparable to synthetic antioxidants against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and formation of peroxides. Presence of 0.6% and 5% of oregano extract in the clove extracts obtained from the clove–oregano plant mixtures improved their antioxidant activity with respect to the extract from pure clove. Clove extract showed moderate antibacterial activities against selected Staphylococcus and Enterococcus bacterial strains. Presence of 50% of the oregano extract improved antibacterial activity of clove extract against all tested strains and resulted in a synergistic antibacterial activity against Methicillin-resistant Staphylococcus haemolyticus strain (MIC ? 1.25 μg/mL). Study demonstrated great potential of supercritical clove extract as natural functional ingredient and the possibility of increasing its antioxidant and antibacterial efficiencies in order to apply lower concentrations and to reduce undesirable flavour notes and toxicological effects in final products.     

Studies on the anthocyanin profile and biological properties from the fruits of Acanthopanax senticosus (Siberian Ginseng)

The anthocyanin profile and biological activities, including antioxidant, xanthine oxidase inhibitory, angiotensin converting enzyme (ACE) inhibitory, and anticancer of Acanthopanax senticosus fruits were evaluated for the first time. The acidified 80% methanol extract of this species exhibited high biological properties at a concentration of 60 μg/ml. Moreover, cyanidin-3-O-(2″-O-xylosyl)-glucoside was identified using C₁₈ column chromatography, NMR spectroscopy, and HPLC-DAD-ESI/MS analysis. This compound was present at 5.2 mg/g, representing approximately 91% of the total peak area and possessed strong antioxidant effects against DPPH, ABTS, and hydroxyl radicals (IC₅₀ of 85.2, 43.7, and 126.6 μg/ml, respectively). Cyanidin-3-O-(2″-O-xylosyl)-glucoside also exhibited significant inhibitory activities against xanthine oxidase and ACE (IC₅₀: 55.5 and 47.1 μg/ml, respectively). Especially, LNCap (prostate), MOLT-4F (leukaemia), and ACHN (renal) cell lines exhibited potent anticancer effects, with IC₅₀ of 5.2, 11.2, and 22.5 μg/ml, respectively, in comparison with other cancer cell lines. Therefore, A. senticosus fruit may be utilised as an effective source for food and nutraceutical uses due to its high anthocyanin content as well as various biological properties.     

Yerba mate tea (Ilex paraguariensis): Phenolics,antioxidant capacity and in vitro inhibition of colon cancer cell proliferation

Mate tea (MT) is a rich source of phenolic compounds that vary depending on geographical origin and mode of preparation. Total phenolic concentration and antioxidant capacity of Mate tea (Ilex paraguariensis) products were determined in this work. In addition, a representative MT was tested for in vitro inhibition of human colon carcinoma cell proliferation. Total polyphenol concentration, was measured using Folin–Ciocalteau method, ranged from 90 to 176 mg gallic acid eq (GAE)/g dry leaves (DL) in traditional MT and from 40 to 113 mg GAE/g DL in MT added with other flavouring ingredients. It was estimated that a cup of tea (250 ml) containing one teaspoon (5 g) of instant MT could provide an average intake of 1.5 g GAE. Fresh tea (FT) from Mate leaves displayed high antioxidant capacity (85 ± 1%) and preferentially inhibited 50% of net growth of human colorectal adenocarcinoma cells CaCo-2 (GI₅₀ = 1.0 ± 0.03 μg/ml) and HT-29 (GI₅₀ = 105.2 ± 15.2 μg/ml) when compared with the CCD-33Co normal colon fibroblast cell line (GI₅₀ > 300 μg/ml). MT inhibited in vitro colon cancer cell proliferation possibly mediated via pro-oxidant activities, therefore represents a potential source of chemopreventive agents that deserve further investigation.     

Inhibition of dipeptidyl peptidase IV (DPP-IV) by proline containing casein-derived peptides

Dipeptides with a C terminal Pro inhibit dipeptidyl peptidase IV (DPP-IV), a key enzyme in incretin hormone processing. It was hypothesised that tri- and tetrapeptides with a proline at the C-terminus may also be DPP-IV inhibitors. Therefore, an in silico hydrolysis approach was used to release short (4 ? amino acids) C terminal Pro peptides from the individual caseins which constitute Pro rich substrates. This was achieved using theoretical digestion of caseins with a prolyl oligopeptidase activity. Fifteen peptides were subsequently selected for in vitro DPP-IV inhibitory analysis. Stability of these peptides to gastrointestinal enzymes was also evaluated in silico and the predicted breakdown peptides were assessed for their DPP-IV inhibitory and antioxidant potential. New DPP-IV inhibitors were identified, the most potent being Phe-Leu-Gln-Pro (IC₅₀ 65.3 ± 3.5 μM). A low in vitro antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging) activity was also associated with the peptides studied. The strategy presented highlights the utility of employing an in silico approach for the prediction of food-derived peptides with a potential role in glycaemic management for subsequent development of functional foods.     

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.     

Antimicrobial activity of whey protein based edible films incorporated with oregano,rosemary and garlic essential oils

The use of edible films to release antimicrobial constituents in food packaging is a form of active packaging. Antimicrobial properties of spice extracts are well known, however their application to edible films is limited. In this study, antimicrobial properties of whey protein isolate (WPI) films containing 1.0–4.0% (wt/vol) ratios of oregano, rosemary and garlic essential oils were tested against Escherichia coli O157:H7 (ATCC 35218), Staphylococcus aureus (ATCC 43300), Salmonella enteritidis (ATCC 13076), Listeria monocytogenes (NCTC 2167) and Lactobacillus plantarum (DSM 20174). Ten millilitres of molten hard agar was inoculated by 200 μl of bacterial cultures (colony count of 1 × 10⁸ CFU/ml) grown overnight in appropriate medium. Circular discs of WPI films containing spice extracts, prepared by casting method, were placed on a bacterial lawn. Zones of inhibition were measured after an incubation period. The film containing oregano essential oil was the most effective against these bacteria at 2% level than those containing garlic and rosemary extracts (P < 0.05). The use of rosemary essential oil incorporated into WPI films did not exhibit any antimicrobial activity whereas inhibitory effect of WPI film containing garlic essential oil was observed only at 3% and 4% level (P < 0.05). The results of this study suggested that the antimicrobial activity of some spice extracts were expressed in a WPI based edible film.     

Antifungal activity of five different essential oils in vapour phase for the control of Colletotrichum gloeosporioides and Lasiodiplodia theobromae in vitro and on mango

Mango fruit has high commercial value; however, major postharvest losses are encountered throughout the supply chain due to postharvest diseases. These results lead to the search for natural fungicide for postharvest diseases control. The antifungal effects of five essential oils (thyme, clove, cinnamon, anise and vitex) were assessed by disc volatilisation method. Thyme oil vapours at 5 μL per Petriplate, and clove and cinnamon oil at 8 μL per Petriplate showed 100% growth inhibition of mango pathogens in vitro. GC/MS analysis of essential oil showed thymol (23.88), o‐cymol (23.88) and terpinolene (23.88) as the major constituents of thyme oil. Clove and cinnamon oils contain 3‐allyl‐2‐methoxyphenol (37.42%) and benzofuran 3‐methyl (17.97%), respectively. Thyme oil as a fumigant at 66.7 μL L^?1 showed a significant (P < 0.05) inhibition on postharvest pathogens of mango fruits stored at 25 °C for 6 days. Results of our study suggest the possibility of using thyme oil as an alternate natural fungicide to manage postharvest diseases in mango.     

Air-dried capsicum annuum var. acuminatum medium and big: Determination of bioactive constituents,antioxidant activity and carbohydrate-hydrolyzing enzymes inhibition

In the present study the total phenols, flavonoids, carotenoids and capsaicinoids content, the in vitro antioxidant and hypoglycemic activities of extracts of air-dried fruits from two Capsicum annuum cultivars were investigated. A different composition between the two cultivars was evidenced. C. annuum var. acuminatum medium extract presented a major content of phenols, carotenoids, capsaicin and dihydrocapsaicin while C. annuum var. acuminatum big extract is characterized by the highest quercetin, luteolin and kaempferol content with 68.0, 87.6 and 29.7 μg/g dried weight, respectively, analyzed by HPLC. Medium pepper showed the highest radical scavenging activity in DPPH assay (IC₅₀ of 85.3 μg/ml) while big pepper have an interesting activity in ABTS assay (IC₅₀ of 16.4 μg/ml) and the highest inhibition of linoleic acid oxidation with an IC₅₀ value of 1.2 μg/ml after 30 min of incubation. A selective inhibitory activity against α-amylase was demonstrated for C. annuum var. acuminatum big lipophilic fraction (IC₅₀ values of 8.7 μg/ml). The obtained results suggest that C. annuum cultivars could be used as valuable flavor with functional properties for foods.     

The effect of time and origin of harvest on the in vitro biological activity of Palmaria palmata protein hydrolysates

The effect of starting protein composition, and the origin and time of harvesting on the in vitro tyrosinase, dipeptidyl peptidase (DPP) IV and angiotensin converting enzyme (ACE) inhibitory and antioxidant activity of Palmaria palmata protein hydrolysates were investigated. Electrophoretic profiles showed significant differences in aqueous protein extracts obtained from the red macroalga Palmaria palmata harvested at different times of the year. No significant difference was observed in aqueous protein profiles extracted from wild and aquacultured samples of Palmaria palmata. Protein extracts from Palmaria palmata samples harvested from wild plants in April, July and October, and samples cultivated on longlines and harvested in April were hydrolysed with Alcalase 2.4 L and Corolase PP. The hydrolysates, when tested at 10 mg/ml, were shown to inhibit tyrosinase by 37–56%. The oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) values of the hydrolysates ranged from 323–494 and 8.9–19.9 μmol trolox equivalents per gram, respectively. The Palmaria palmata hydrolysates inhibited DPP-IV (IC₅₀: 1.60–4.24 mg/mL) and ACE (IC₅₀: 0.14–0.35 mg/mL) activities. The starting protein composition had a significant effect on the tyrosinase inhibitory activity, while protein composition and hydrolytic enzyme preparation had a significant effect on DPP-IV inhibitory and antioxidant activities. In general, the origin of the samples, wild or cultivated, had no effect on the in vitro biological activity of the protein hydrolysates. The results show that Palmaria palmata hydrolysates may have potential applications as health enhancing ingredients and as food preservatives due to their antioxidant and tyrosinase inhibitory effects.     

Quantitative evaluation of sanguinarine as an index of argemone oil adulteration in edible mustard oil by high performance thin layer chromatography

A simple analytical procedure based on HPTLC method was developed for the detection of argemone oil adulteration in edible mustard oil using sanguinarine as an index of argemone oil adulteration (measured as % adulteration). The methodology required no elaborate extraction procedure. The quantitation was achieved by densitometric scanning of the chromatogram in fluorescence/reflectance mode. Dihydrosanguinarine concentration was determined after its conversion to sanguinarine by UV (366 nm) irradiation, for a period of 15 min. The limit of detection (LOD) of sanguinarine in argemone oil was estimated as 1 ng per 6 mm band with a signal-to-noise ratio of 3:1 and limit of quantitation in the samples was estimated as 3 ng per 6 mm band with a signal-to-noise ratio of 10:1. The total content of sanguinarine (sanguinarine + dihydrosanguinarine) in argemone oil samples were in the range of 4.84–5.79 mg/ml of oil. Standard sanguinarine was spiked to edible mustard oil at two levels (50 and 100 μg/ml) and recoveries were found to be 79% and 82%, respectively. A linear regression plot (y = 40.44 (±0.014)x − 5.81 (±0.078)) was generated between the percent adulteration of argemone oil in edible mustard oil and the concentration of sanguinarine in the edible mustard oil spiked with various levels of argemone oil (1–30%). Analyzing the adulterated edible mustard oil samples collected from the area, wherein an outbreak of epidemic dropsy was reported in the recent past, validated this linear regression plot. The percent adulteration in these samples was found to be in the range of 1.22–8.77%. Food and forensic laboratories can use this method routinely in order to assess the adulteration of edible oils by argemone oil and in poisoning cases due to argemone oil toxicity.     

The effects of composite coatings containing chitosan and Mentha (piperita L. or x villosa Huds) essential oil on postharvest mold occurrence and quality of table grape cv. Isabella

The effects of coatings containing shrimp chitosan and the essential oil from Mentha piperita L. (MPEO) or M. villosa Huds (MVEO) to control common mold infections in table grape cv. Isabella (Vitis labrusca L.) that were caused by Aspergillus niger, Botrytis cinerea, Penicillium expansum and Rhizopus stolonifer were evaluated. The effects of the coatings on physicochemical and sensory characteristics of the grapes were also assessed. The coatings containing chitosan (4, 8 mg/mL) and MPEO or MVEO (1.25, 2.5, 5 μL/mL) delayed the mold growth and reduced the incidence of infections caused by all test fungi in grapes during storage at room and low temperatures. The coatings (chitosan 4 mg/mL; MPEO or MVEO 1.25, 2.5 μL/mL) did not negatively affect the physicochemical and sensory characteristics of grapes. From these results, coatings containing chitosan and MPEO or MVEO are potential postharvest treatments to control common mold infections in table grape cv. Isabella.Industrial relevanceIn table grapes, the reduction of losses resulting from fungal rot is a major goal of postharvest technology, which seeks to use effective methods to control the contamination and the growth of phytopathogenic fungi. However, the negative consumer perception of synthetic fungicides used for many years to solve the problem of mold infections in table grapes and the development of fungicide-resistant strains have impelled researchers to study the efficacy of natural compounds against postharvest pathogenic fungi. In this context, edible coatings composed of chitosan and essential oils have been considered as an environmentally friendly and added-value technology to control fungal postharvest decay in table grapes because of their biodegradability and lack of phytotoxicity. In this study, the authors evaluated composite coatings that contained shrimp chitosan and reduced amounts of Mentha (piperita L. or x vilosa Huds) essential oil as postharvest treatment to control the occurrence of mold infections caused by fungi in table grape cv. Isabella (Vitis labrusca L.), and their effects on the quality attributes of this fruit during storage. The tested composite coatings are presented as possible alternative technologies to control fungal infections and related post-harvest losses in table grape cv. Isabella.     

Addition of seaweed (Laminaria digitata) extracts containing laminarin and fucoidan to porcine diets: Influence on the quality and shelf-life of fresh pork

A seaweed extract containing laminarin (L) and fucoidan (F) (L/F) was manufactured from brown seaweed (Laminaria digitata) in spray-dried (L/F-SD) and wet (L/F-WS) forms. The effect of supplementation of pig diets with L/F-SD and L/F-WS (L, 500 mg/kg feed; F, 420 mg/kg feed) for 21 days pre-slaughter, on quality indices of fresh M. longissimus dorsi (LD) steaks was examined. Susceptibility of porcine liver, heart, kidney and lung tissue homogenates to iron-induced (1 mM FeSO₄) lipid oxidation was also investigated. Dietary supplementation with L/F did not increase plasma total antioxidant status (TAS). In LD steaks stored in modified atmosphere packs (80% O₂:20% CO₂) (MAP) for up to 15 days at 4 °C, muscle pH, surface colour (CIE ‘L*’ lightness, ‘a*’ redness and ‘b*’ yellowness values) and microbiology (psychrotrophic and mesophilic counts, log CFU/g pork) were unaffected by dietary L/F. In general, levels of lipid oxidation (TBARS, mg MDA (malondialdehyde)/kg pork) followed the order: C > LF-SD > L/F-WS. A statistically significant reduction in lipid oxidation (P < 0.05) was observed in LD steaks from 75% of pigs (n = 6) fed with L/F-WS compared to controls. Iron-induced lipid oxidation increased in liver, heart, kidney and lung tissue homogenates over the 24 h storage period and dietary L/F-WS reduced lipid oxidation to the greatest extent in liver tissue homogenates. Results demonstrate potential for the incorporation of marine-derived bioactive antioxidant components into muscle foods via the animal's diet.