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1.
Food Microbiol ; 85: 103282, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31500713

RESUMO

Two biopreservation approaches for fresh lettuce, rocket salad, parsley and spinach were studied. The potential of Pediococcus pentosaceus DT016, as a protective culture, to suppress Listeria monocytogenes in vegetables during storage was evaluated. The pathogen numbers in the vegetables inoculated with P. pentosaceus DT016 were significantly (p < 0.01) lower throughout the storage period and, at the last storage day, a minimum difference of 1.4 log CFU/g was reported when compared with the vegetables without the protective culture. Moreover, by using two levels of L. monocytogenes (about 6 and 4 log CFU/g), it was observed that the antagonist effect of P. pentosaceus was higher for the lower pathogen numbers. The second approach evaluated a pediocin DT016 solution to inactivate and control L. monocytogenes proliferation. The pathogen load was studied after washing with: water, chlorine and the pediocin solution and along storage at 4  °C. Comparing the various washing solutions, the vegetables washed with pediocin presented significantly (p < 0.01) lower pathogen numbers throughout storage, by a minimum of 3.2 and 2.7 log CFU/g, than in vegetables washed with water and chlorine, respectively. The proposed methodologies are promising alternatives to maintain the safety of fresh vegetables during extended storage at refrigeration temperature.


Assuntos
Antibiose , Microbiologia de Alimentos/métodos , Conservação de Alimentos/métodos , Listeria monocytogenes/fisiologia , Verduras/microbiologia , Carga Bacteriana , Cloro/farmacologia , Temperatura Baixa , Qualidade de Produtos para o Consumidor , Manipulação de Alimentos/métodos , Alface/microbiologia , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/crescimento & desenvolvimento , Pediocinas/farmacologia , Pediococcus pentosaceus/fisiologia , Petroselinum/microbiologia , Refrigeração , Spinacia oleracea/microbiologia , Água
2.
J Sci Food Agric ; 100(1): 145-153, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31471914

RESUMO

BACKGROUND: Previous reports have addressed the effectiveness of postharvest methyl jasmonate (MeJA) treatments on maintaining quality properties of pomegranate fruit during storage. However, there is no literature regarding the effects of preharvest MeJA treatments on pomegranate 'Mollar de Elche' crop yield, fruit ripening, quality attributes and bioactive compounds content (at harvest or after long-term storage), which were evaluated in this research. RESULTS: Preharvest MeJA treatments (1, 5, and 10 mmol L-1 ) increased pomegranate crop yield. MeJA at 1 and 5 mmol L-1 accelerated the on-tree ripening process, while it was delayed with 10 mmol L-1 . Losses in fruit weight, firmness and organic acids during storage at 10 °C were delayed in MeJA treated fruit, leading to quality maintenance. In addition, MeJA treatments improved arils colour due to increased concentration of total and individual anthocyanins, at harvest and during storage. Total phenolic and ascorbic acid contents and total antioxidant activity [hydrophilic (H-TAA) and lipophilic (L-TAA) fractions] were also higher in arils from treated pomegranate fruits than in controls. CONCLUSION: Preharvest treatments with MeJA could be a promising tool to improve pomegranate crop yield, fruit quality and its content in bioactive compounds at harvest and during storage. The higher effects were obtained with MeJA at 5 mmol L-1 dose, which could be the selected treatment for practical application purposes. © 2019 Society of Chemical Industry.


Assuntos
Acetatos/farmacologia , Ciclopentanos/farmacologia , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Frutas/química , Lythraceae/efeitos dos fármacos , Oxilipinas/farmacologia , Extratos Vegetais/análise , Antocianinas/análise , Antioxidantes/análise , Ácido Ascórbico/análise , Cor , Armazenamento de Alimentos , Frutas/efeitos dos fármacos , Lythraceae/química , Fenóis/análise
3.
J Sci Food Agric ; 100(1): 184-192, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31472017

RESUMO

BACKGROUND: Slight acidic electrolyzed water (SAEW) has been widely used in cleaning systems of fruit and vegetables. It strongly reduces microbial contamination. However, no information is available on whether SAEW offers the potential for fresh jujube cleaning. The purposes of this study were, first, to compare the effectiveness of SAEW with commercial sanitizers (i.e. sodium hypochlorite (NaClO) or calcium hypochlorite (Ca(ClO)2 )) on 'Jiancui' jujube; second, to determine the response of fruit decay, tissue calcium (Ca) content, and quality attributes to dip application of calcium nitrate (Ca(NO3 )2 ) by concentration; and third, to investigate the effects of SAEW combined with Ca(NO3 )2 or calcium acetate (Ca(OAc)2 )) on fruit Ca uptake, quality attributes, and bioactive compounds. RESULTS: Fruits washed with NaClO, Ca(ClO)2 , or an SAEW solution showed no difference in reduction of decay incidence. In contrast to NaClO treatment, SAEW or Ca(ClO)2 significantly retarded losses in fruit firmness (FF), green color (hue angle), and skin lightness (L*), and maintained intact pericarp tissue structure during storage at 1 °C. Application of Ca(NO3 )2 at 5-10 g L-1 effectively promoted Ca2+ uptake and minimized declines in FF and L* value but had no effect on decay development. Adding 10 g L-1 Ca(NO3 )2 or Ca(OAc)2 to SAEW provided an additional benefit in increasing decay resistance, increasing Ca2+ into fruit and increasing levels of bioactive compounds in jujube fruit. CONCLUSION: SAEW in combination with Ca(NO3 )2 or Ca(OAc)2 has commercial potential for fresh jujube disinfection and improving storage quality as a result of the cleaning processes. © 2019 Society of Chemical Industry.


Assuntos
Acetatos/farmacologia , Compostos de Cálcio/farmacologia , Cálcio/análise , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Frutas/química , Nitratos/farmacologia , Ziziphus/efeitos dos fármacos , Eletrólise , Armazenamento de Alimentos , Frutas/efeitos dos fármacos , Controle de Qualidade , Água/química , Ziziphus/química
4.
J Sci Food Agric ; 100(2): 656-664, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31577841

RESUMO

BACKGROUND: The frozen preservation of lamb meat could be crucial for successful international trade. The shelf life of thawed meat is shorter than that of fresh meat, so techniques or procedures are required to improve post-thawing meat quality attributes. This study investigated the effect of alginate-based edible coatings after the incorporation of essential oils of thyme (Thymus vulgaris L.) and garlic (Allium sativum L.) on thawed lamb meat (longissimus thoracis et lumborum muscle) quality after long-term frozen storage. Meat samples came from ten light lambs and the evolution of attributes related to shelf life, such as water-holding capacity, color stability, and lipid oxidation, was monitored during display (1, 4 and 7 days). Four meat treatments were evaluated: control (CON, uncoated meat), edible coat of alginate meat (ECA), and ECA with thyme or garlic essential oils (0.05%) (THY and GAR). RESULTS: The alginate-based edible coatings decreased exudative losses (P < 0.001) and modified color characteristics, especially increasing yellowness (P < 0.001) and chrome (P < 0.001). GAR decreased redness (P < 0.001) and the oxy/met ratio [R (630/580) wavelength light reflectance] or discoloration [R (630-580)]. THY was the treatment that best retained color during display and also showed a significantly lower lipid oxidation (P < 0.05) than CON and ECA, whereas GAR presented intermediate values. CONCLUSION: The addition of bioactive essential oils to alginate-based edible coatings improved preservation and shelf life of lamb meat after thawing. © 2019 Society of Chemical Industry.


Assuntos
Conservação de Alimentos/métodos , Conservantes de Alimentos/análise , Alho/química , Carne/análise , Óleos Voláteis/análise , Extratos Vegetais/análise , Thymus (Planta)/química , Animais , Armazenamento de Alimentos , Lipídeos/química , Oxirredução , Ovinos
5.
Int J Food Microbiol ; 309: 108330, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31493566

RESUMO

A probabilistic model based on logistic regression was developed for a target log reduction of microorganisms inactivated by high hydrostatic pressure. Published inactivation data of Salmonella Typhimurium in broth for 4 and 5 log reductions, and Escherichia coli in buffer and carrot juice for 5 log reduction were used. The probabilities of achieving 4 or 5 log reductions for S. Typhimurium in broth and 5 log reduction for E. coli in buffer and carrot juice could be calculated at different pressure, temperature and time levels. The fitted interfaces of achieving/not achieving the target log reduction were consistent with the experimental data. Although the reliability of the predictions of the developed models could be questioned due to strain variation and different food matrix, a validation study has demonstrated that the developed models could be used to predict the target log reduction of these microorganisms at different pressure, temperature and time levels. This study has indicated that the probabilistic modeling for target log reductions can be useful tool for HHP inactivation of microorganisms, but further studies could be performed with several other factors such as pH and water activity of the food, concentration of certain additives as well as initial number of bacteria present in the food.


Assuntos
Escherichia coli/isolamento & purificação , Microbiologia de Alimentos/métodos , Conservação de Alimentos/métodos , Pressão Hidrostática , Salmonella typhimurium/isolamento & purificação , Contagem de Colônia Microbiana , Reprodutibilidade dos Testes , Temperatura Ambiente
6.
Int J Food Microbiol ; 309: 108328, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31518953

RESUMO

Ultrasound (US) has a high capacity to increase food safety. Although high and/or moderate temperature in combination with US has been studied, the knowledge about cooling/low temperatures as well as its combined effect with chemical preservation methods is scarce. Therefore, the aim of this study was to describe the inactivation of Staphylococcus spp. (SA) present in the natural microbiota of sliced Brazilian dry-cured loin (Socol, BDL) using US (40 kHz and 5.40 W/g) at 1.6-17.9 kJ/g, temperature (T) between 6.4 and 73.6 °C and peracetic acid (PA) between 5.5 and 274.5 mg/L employing the Central Composite Rotatable Design. The model fully describes how the combination of US, T, and PA affects SA inactivation. In BDL, an increase in US acoustic energy density (kJ/g) allows the reduction of T necessary to inactivate SA because of the occurrence of synergistic effect. However, US applied at low T was inefficient. On the other hand, PA was more efficient at low T, since high T degraded this compound at different rates according to the holding T. Therefore, the data indicates a relation between the technologies used in the combined decontamination of sliced BDL improving dry-cured meat safety.


Assuntos
Descontaminação/métodos , Desinfetantes/farmacologia , Conservação de Alimentos/métodos , Carne/microbiologia , Ácido Peracético/farmacologia , Staphylococcus/efeitos dos fármacos , Ondas Ultrassônicas , Brasil , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Inocuidade dos Alimentos/métodos , Staphylococcus/classificação , Staphylococcus/isolamento & purificação , Temperatura Ambiente
7.
J Sci Food Agric ; 99(15): 6859-6867, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31385314

RESUMO

BACKGROUND: In this study, we analyzed the effect of the application of high levels of CO2 (20 kPa CO2 + 20 kPa O2 + 60 kPa N2 ) for 3 days at low temperature on a white table-grape cultivar (Superior Seedless) in comparison with a black one (cv. Autumn Royal) in terms of quality parameters. We also used a solid-state voltammetry methodology to analyze the effect of the 3-day gaseous treatment in berry tissues from both cultivars in the first stage of storage. We determined the role of the non-enzymatic (total phenols, total anthocyanins, and antioxidant activity) and the enzymatic antioxidant (catalase (GCAT), ascorbate peroxidase (VcAPX) gene expression) systems in the behaviors of both cultivars. RESULTS: Our results indicate that the application of a 3-day gaseous treatment was effective in maintaining the quality of black and white table grapes for up to 28 days of storage at 0 °C. The electrochemical methodology applied was useful for differentiating between skin and pulp samples, and between black and white table grape cultivars. Some molecular mechanisms were modulated in the skin of both cultivars to overcome oxidative stress, which was not manifested with the same intensity in grapes treated with CO2 for 3 days. However, some differences were observed in relation to the non-enzymatic system. CONCLUSION: The 3-day gaseous treatment was useful to maintain black and white table grape quality at 0 °C. The voltammetry analysis indicated that CO2 -treated samples from the skin and pulp showed more similarity to freshly harvested ones. © 2019 Society of Chemical Industry.


Assuntos
Antioxidantes/análise , Dióxido de Carbono/farmacologia , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Vitis/efeitos dos fármacos , Antioxidantes/metabolismo , Ascorbato Peroxidases/genética , Ascorbato Peroxidases/metabolismo , Dióxido de Carbono/química , Catalase/genética , Catalase/metabolismo , Cor , Conservantes de Alimentos/química , Armazenamento de Alimentos , Frutas/química , Frutas/efeitos dos fármacos , Gases/farmacologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Vitis/química , Vitis/enzimologia , Vitis/genética
8.
J Microbiol Biotechnol ; 29(8): 1240-1247, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31370118

RESUMO

This study was conducted to examine the inactivation effect of the combined treatment of high hydrostatic pressure (HHP; 400 MPa for 1, 3, and 5 min) and cationic surfactant washing (0.05% benzethonium chloride, BEC) against Listeria monocytogenes inoculated on fresh-cut broccoli (FCB). Washing with BEC at concentrations exceeding 0.05% resulted in 2.3 logreduction of L. monocytogenes counts on FCB, whereas HHP treatment had approximately 5.5- 5.6 log-reductions regardless of the treatment time. Scanning electron microscopy corroborated microbial enumeration, revealing that the combined treatment was more effective in removing L. monocytogenes from FCB than individual treatment with HHP or BEC. Color and total glucosinolate content were maintained after the combined treatment, although the hardness of the FCB slightly decreased. The results clearly suggest that the combined treatment of HHP and BEC washing has potential value as a new sanitization method to improve the microbial safety of FCB.


Assuntos
Brassica/microbiologia , Conservação de Alimentos/métodos , Listeria monocytogenes/efeitos dos fármacos , Tensoativos/farmacologia , Benzetônio/farmacologia , Contagem de Colônia Microbiana , Cor , Contaminação de Alimentos/prevenção & controle , Microbiologia de Alimentos , Qualidade dos Alimentos , Inocuidade dos Alimentos , Pressão Hidrostática , Listeria monocytogenes/crescimento & desenvolvimento
9.
J Food Sci ; 84(9): 2467-2474, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31449337

RESUMO

The antioxidant stability of minced pork treated with thyme and oregano essential oils (EOs) was determined. Minced pork containing different concentrations (0%, 0.3%, 0.6%, or 0.9%) of thyme (TEO) or oregano essential oil (OEO) and packaged under vacuum or modified atmosphere (MAP) (30%O2 /50%CO2 /20%N2 ) was evaluated within 15 days of refrigeration (3 ± 1 °C) storage. EOs were examined for scavenging capacity toward 2,2-diphenyl-1-picrylhydrazyl, nitric oxide radicals, and hydroxyl, and inhibition of lipid peroxidation and ferric ion reducing antioxidant power (butylated hydroxytoluene was used as positive controls). The order of antioxidative effectiveness was as follows: butylated hydroxytoluene > OEO > TEO, with significant differences between agents (P < 0.05). Lipid oxidation in meat was determined by monitoring malondialdehyde (MDA) formation and lipolysis was assessed by measuring the acidity index immediately and after 3, 6, 9, 12, and 15 days of storage. EOs significantly (P < 0.05) increased the stability of minced pork with respect to lipid oxidation compared with the control, and the antioxidative effect was dose-dependent. Moreover, vacuum packaging resulted in mince with significantly lower oxidation and lipolysis levels than modified atmosphere packaged mince (P < 0.05). The results demonstrate that both EOs examined effectively reduced lipid oxidation in raw pork mince after 2 weeks' storage. PRACTICAL APPLICATION: The natural food preservatives market is growing rapidly, as is high demand for organic foods. These results are likely to be of interest to the scientists, researchers, and persons who work in the meat industry. Results and discussion can contribute to a better understanding of antioxidative properties of essential oils in food model. Furthermore, no study has reported the effect of these MAP on pork oxidative stability.


Assuntos
Antioxidantes/química , Conservação de Alimentos/métodos , Conservantes de Alimentos/química , Carne/análise , Óleos Voláteis/química , Origanum/química , Extratos Vegetais/química , Thymus (Planta)/química , Animais , Embalagem de Alimentos , Oxirredução , Refrigeração , Suínos , Vácuo
10.
J Sci Food Agric ; 99(14): 6562-6571, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31321778

RESUMO

BACKGROUND: Excessive reactive oxygen species (ROS) may attack biological macromolecules and induce oxidative stress. The inhibition by ascorbic acid (AsA) on oxidative damage has been reported in fruits, while the barrier effect of ceramide has also been proven. However, there are few reports about the effects of ceramide-AsA interactions to enhance storability and boost antioxidant systems in fruits during storage. This study was conducted to study the synergistic effects of AsA in combination with ceramide on the quality of postharvest strawberry (Fragaria anannasa cv. Tianbao). RESULTS: Treatment with 100 mg L-1 AsA plus 1.2 mmol L-1 ceramide significantly delayed the rot of strawberries, reduced the water loss and the contents of ROS, malonaldehyde (MDA), and proline, however, increased the contents of total flavonoids, total phenols, and anthocyanins compared with other treatments. Also, treatment with 100 mg L-1 AsA plus 1.2 mmol L-1 ceramide significantly increased the activities of peroxidase (POD) and superoxide dismutase (SOD) but inhibited the activity of polyphenol oxidase (PPO). CONCLUSION: It is suggested that treatment with 100 mg L-1 AsA plus 1.2 mmol L-1 ceramide could significantly reduce the oxidative damage and maintain the storage quality of strawberries during storage by enhancing the antioxidant systems. © 2019 Society of Chemical Industry.


Assuntos
Antioxidantes/metabolismo , Ácido Ascórbico/farmacologia , Ceramidas/farmacologia , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Fragaria/efeitos dos fármacos , Catalase/metabolismo , Sinergismo Farmacológico , Armazenamento de Alimentos , Fragaria/química , Fragaria/metabolismo , Frutas/química , Frutas/efeitos dos fármacos , Frutas/metabolismo , Malondialdeído/metabolismo , Estresse Oxidativo , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo
11.
J Sci Food Agric ; 99(14): 6572-6581, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31325328

RESUMO

BACKGROUND: As a pretreatment before drying, the purpose of osmotic dehydration (OD) is to reduce the initial water content of samples and shorten the drying time. When OD is combined with pulse vacuum, the mass transfer is enhanced. Furthermore, the properties of materials, which affect the absorption and dissipation of microwaves, can be changed by OD. In this work, pulsed vacuum osmotic dehydration (PVOD) with sucrose solution was adopted before microwave freeze-drying (MFD). The effects of PVOD on the drying characteristics and quality of dried products were studied. RESULTS: Results showed that the unfrozen water content was increased by PVOD, which made the dielectric constant and loss factor of Chinese yam larger than that of untreated samples, and the difference amplified with the increasing temperature. Thus, the shortened drying time (up to 38.5%) and increased average drying rate (up to 16.8%) were achieved by MFD combined with PVOD. While in traditional freeze-drying, PVOD resulted in slightly shortened drying time but decreased drying rate. The mechanism of PVOD on improving drying rate of MFD was analyzed from the perspective of unfrozen water content and dielectric properties. Furthermore, the quality assessments indicated that PVOD treatment retained a better color and improved the total phenolic content of dried yams compared to untreated and dried samples. CONCLUSION: PVOD using sucrose solution was an effective method to change the characteristics of yam, enhancing the MFD rate and improving the product qualities. © 2019 Society of Chemical Industry.


Assuntos
Dessecação/métodos , Dioscorea/química , Conservação de Alimentos/métodos , Tubérculos/química , Água/análise , Cor , Dessecação/instrumentação , Conservação de Alimentos/instrumentação , Liofilização , Micro-Ondas , Osmose , Fenóis/análise
12.
J Sci Food Agric ; 99(14): 6296-6306, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31260121

RESUMO

BACKGROUND: Blueberries are appreciated by consumers for their rich natural antioxidants and their good nutritional and health functions. However, blueberries are very perishable due to microbial infection and metabolic aging after harvest. Ethanol has been shown to have the effect of controlling postharvest microorganisms and improving storage quality of fruits and vegetables. This study aimed to clarify the effects of ethanol on the appearance quality and flavor attributes of postharvest blueberries. Blueberries were treated with ethanol (250, 500, and 1000 µL L-1 ) and stored at 0 ± 0.5 °C, 90% relative humidity (RH), for 40 days. RESULTS: The results indicated that ethanol treatment could slow the decline of blueberry firmness and reduce the decay rate significantly in a dose-dependent manner. The soluble solids content (SSC) and titratable acidity (TA) of ethanol-treated blueberries increased significantly (P < 0.05), improving the taste of the blueberries. The activities of alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC) were stimulated with the accumulation of ethanol in blueberries, which catalyzed the conversion of ethanol, acetaldehyde, and pyruvate, increasing their levels in blueberries. More volatiles, especially esters, were detected in ethanol-treated blueberries, e.g. methyl acetate, ethyl acetate, ethyl propanoate, ethyl isobutyrate, ethyl 2-methylbutanoate, ethyl isovalerate, ethyl 3-methyl-2-butenoate, diethyl sebacate, and isopropyl myristate. CONCLUSION: The preservative effect of ethanol on blueberry was significantly affected by ethanol concentration. In this study, the effect of 500 µL L-1 ethanol fumigation on blueberry was the best in terms of appearance quality (firmness and decay rate) and flavor attributes (SSC, TA, and volatiles). © 2019 Society of Chemical Industry.


Assuntos
Mirtilos Azuis (Planta)/química , Etanol/farmacologia , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Frutas/efeitos dos fármacos , Mirtilos Azuis (Planta)/efeitos dos fármacos , Frutas/química , Fumigação/métodos , Humanos , Controle de Qualidade , Paladar , Compostos Orgânicos Voláteis/análise
13.
Food Chem ; 299: 125122, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31288165

RESUMO

To ease the mass exchange in fruit tissues, cutting and blanching are traditionally performed. However, recently, unconventional methods such as sonication are becoming more popular, which cause several alterations of physical and chemical properties as well as microstructure changes. The aim of this work was to evaluate the distribution of water inside the cranberry fruits, microstructural changes and sugars content, following traditional and sonication pre-treatments in osmotic solutions. TD-NMR spectroscopy was used to measure the transverse relaxation time (T2) and intensity of proton pools in different cellular compartments. The microstructure of the samples was evaluated by SEM microscopy, sugars content by HPLC and sucrose melting temperature and enthalpy by DSC. Different pre-treatments appeared to promote microstructure alterations and loss of water from vacuole and cytoplasm/extracellular space, more pronounced in cut and blanched samples. Cutting and blanching followed by osmotic dehydration with assisted sonication eased sucrose penetration into the tissue.


Assuntos
Conservação de Alimentos/métodos , Frutas/química , Açúcares/análise , Vaccinium macrocarpon/química , Água/metabolismo , Varredura Diferencial de Calorimetria , Dessecação , Frutas/ultraestrutura , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Varredura , Osmose , Sonicação , Sacarose/análise , Temperatura Ambiente , Vaccinium macrocarpon/ultraestrutura
14.
Food Chem ; 299: 125104, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31279125

RESUMO

The role of protein denaturation in formation of thaw loss is currently not well understood. This study investigated denaturation of myofibrillar and sarcoplasmic proteins of pork loins caused by freezing-thawing in relation to freezing rate. Compared to fast freezing, slow freezing caused 28% larger thaw loss, decreased water-holding capacity of myofibrils and increased surface hydrophobicity, indicating more pronounced denaturation of myofibrillar proteins. We here propose a model: In slow freezing protons are concentrated in the unfrozen water resulting in reduced pH in proximity of structural proteins causing protein denaturation. In parallel, large ice crystals are formed outside of muscle fibers resulting in transversal shrinkage. In fast freezing small ice crystals trap protons and cause less severe protein denaturation and reduced thaw loss. Differential scanning calorimetry and tryptophan fluorescence spectra indicated sarcoplasmic protein denaturation in drip due to freezing-thawing. However, sarcoplasmic protein denaturation was independent of freezing rate.


Assuntos
Congelamento , Proteínas Musculares/química , Miofibrilas/química , Desnaturação Proteica , Carne Vermelha , Animais , Varredura Diferencial de Calorimetria , Conservação de Alimentos/métodos , Interações Hidrofóbicas e Hidrofílicas , Gelo , Músculos Paraespinais/química , Carne Vermelha/análise , Espectrometria de Fluorescência , Triptofano/química , Água/química
15.
Environ Sci Pollut Res Int ; 26(25): 25414-25431, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31313235

RESUMO

Fungal and mycotoxin contamination of stored food items is of utmost concern throughout the world due to their hazardous effects on mammalian systems. Most of the synthetic chemicals used as preservatives have often been realised to be toxic to humans and also cause adverse environmental effects. In this respect, use of different plant products especially essential oils (EOs) and their bioactive compounds has been recognized as a green strategy and safer alternatives to grey synthetic chemicals in view of their long traditional use. The current nanoencapsulation technology has strengthened the prospective of EOs and their bioactive compounds in food preservation by enhancing their bioactivity and mitigating other problems regarding their large-scale application. Although, the antimicrobial potential of EOs and their bioactive compounds has been reviewed time to time by different food microbiologists, but very less is known about their mode of action. Based on these backgrounds, the present article provides an account on the antifungal and antimycotoxigenic mode of action of EOs as well as their bioactive compounds. In addition, the article also deals with the application of currently used nanoencapsulation approach to improve the stability and efficacy of EOs and their bioactive compounds against mycotoxigenic fungi causing deterioration of stored food items so as to recommend their large-scale application for safe preservation and enhancement of shelf life of food items during storage.


Assuntos
Antifúngicos/farmacologia , Contaminação de Alimentos/análise , Fungos/efeitos dos fármacos , Micotoxinas/análise , Óleos Voláteis/química , Antifúngicos/química , Microbiologia de Alimentos , Conservação de Alimentos/métodos , Humanos , Óleos Voláteis/farmacologia , Conservantes Farmacêuticos , Estudos Prospectivos
16.
J Food Sci ; 84(8): 2190-2198, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31313308

RESUMO

A new microbial decontamination system combining washing with a natural antimicrobial solution and coating with a carnauba wax (CW)-based antimicrobial coating was developed and its effects on mandarin storability were investigated. Mandarins were washed with an antimicrobial solution and/or coated with grapefruit seed extract-CW (GSE/CW). Values for the disease incidence of Penicillium digitatum in untreated mandarins; mandarins coated with GSE/CW without washing; and mandarins coated with GSE/CW after washing with a fumaric acid (FA) solution of slightly acidic electrolyzed water, a highly activated calcium oxide (CaO) aqueous solution, or CaO solution followed by FA solution were 96.0, 70.0, 78.8, 50.0, and 72.2%, respectively. GSE/CW coating after CaO washing was most effective in inhibiting P. digitatum growth during storage at 25 °C. Compared to untreated samples, GSE/CW coating alone or after CaO washing retained CO2 generation, firmness, and total polyphenol content of mandarins at 25 °C. Such treatments also effectively maintained mandarin pH, ascorbic acid concentration, and antioxidant capacity at both 4 and 25 °C. Moreover, GSE/CW coating after CaO washing more effectively inhibited P. digitatum growth at 25 °C and maintained ascorbic acid concentration and antioxidant capacity at 4 and 25 °C than GSE/CW coating alone. The microbial decontamination system integrating CaO washing and GSE/CW coating demonstrates potential for improving mandarin storability by inhibiting P. digitatum growth and improving the preservation of quality properties and sensory characteristics. PRACTICAL APPLICATION: This is the first study to develop a microbial decontamination system involving both washing with a natural antimicrobial solution and carnauba wax coating containing grapefruit seed extract to improve the storability of fruits. This system demonstrated a primary effect of inhibiting fungi that cause mandarin surface decay at 25 °C via the highly activated calcium oxide wash and secondary effects of delaying quality degradation and inhibiting fungal growth by the action of the antimicrobial coating. These effects led to improvements in mandarin storability, along with enhanced visual appeal while not affecting taste, flavor, or texture.


Assuntos
Anti-Infecciosos/farmacologia , Compostos de Cálcio/farmacologia , Citrus/microbiologia , Descontaminação/métodos , Conservação de Alimentos/métodos , Frutas/microbiologia , Óxidos/farmacologia , Citrus/química , Frutas/química , Penicillium/efeitos dos fármacos , Penicillium/crescimento & desenvolvimento , Água/análise , Ceras/análise
17.
Carbohydr Polym ; 222: 114981, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31320073

RESUMO

The incorporation of antimicrobial compounds into natural polymers can promote increased shelf life and ensure food safety. The aim of this study was to evaluate the antibacterial activity, morphological, optical, mechanical, and barrier properties of corn starch films containing orange (Citrus sinensis var. Valencia) essential oil (OEO). The corn starch films were prepared using the casting method. OEO and the corn starch films incorporated with OEO showed higher antibacterial activity against Staphylococcus aureus and Listeria monocytogenes. The addition of OEO to the films increased the morphological heterogeneity and contributed to the reduction of the tensile strength and elongation of the films, and it increased the moisture content, water solubility, and water vapor permeability. The water vapor permeability and partial or total solubility of a film in water prior to consumption of a product are of interest when the film is used as food coating or for encapsulation of specific molecules.


Assuntos
Antibacterianos , Conservação de Alimentos/métodos , Conservantes de Alimentos , Óleos Voláteis , Amido , Antibacterianos/química , Antibacterianos/farmacologia , Conservantes de Alimentos/química , Conservantes de Alimentos/farmacologia , Listeria monocytogenes/efeitos dos fármacos , Óleos Voláteis/química , Óleos Voláteis/farmacologia , Óleos Vegetais/química , Óleos Vegetais/farmacologia , Solubilidade , Staphylococcus aureus/efeitos dos fármacos , Amido/química , Amido/farmacologia , Resistência à Tração
18.
J Sci Food Agric ; 99(14): 6408-6417, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31283020

RESUMO

BACKGROUND: Blood orange is sensitive to chilling injury (CI) depending on cultivar and storage temperature. Postharvest treatments with γ-aminobutyric acid (GABA), methyl jasmonate (MeJA), or methyl salicylate (MeSA) are known to alleviate CI. γ-Aminobutyric acid aqueous solution, applied at 20 and 40 mM, was vacuum-infiltrated at 30 kPa for 8 min at 20 °C. Methyl jasmonate or MeSA vapor treatments were applied separately at 50 and 100 µM by putting the fruit in 20 L plastic containers for 18 h at 20 °C. There have been no reports about postharvest treatments of GABA, MeJA, or MeSA on enhancing the tolerance of 'Moro' blood orange to chilling during long-term cold storage at 3 °C for 150 days, which was the subject of this study. RESULTS: All treatments significantly alleviated CI symptoms of blood orange manifested by lower electrolyte leakage (EL), malondialdehyde (MDA), hydrogen peroxide (H2 O2 ) concentrations, and higher proline content in flavedo during storage. The largest effects were obtained with 100, 50 µM, and 40 mM for MeSA, MeJA, and GABA, respectively, which enhanced the activity of the antioxidant enzymes catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD), and phenylalanine ammonia-lyase (PAL). On the other hand, these treatments suppressed peroxidase (POD) and polyphenol oxidase (PPO) activities. CONCLUSION: The mechanisms involved in enhancing the tolerance of 'Moro' blood orange to chilling could involve scavenging H2 O2 by increasing the activity of antioxidant enzymes, higher PAL/PPO activity ratio, and osmoregulation by increasing proline content. These changes led to the maintenance of the epidermis structure. This was confirmed by scanning electron microscopy (SEM) micrographs. © 2019 Society of Chemical Industry.


Assuntos
Acetatos/farmacologia , Citrus sinensis/efeitos dos fármacos , Ciclopentanos/farmacologia , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Frutas/efeitos dos fármacos , Oxilipinas/farmacologia , Salicilatos/farmacologia , Ácido gama-Aminobutírico/farmacologia , Ascorbato Peroxidases/metabolismo , Catalase , Citrus sinensis/química , Temperatura Baixa , Conservação de Alimentos/instrumentação , Armazenamento de Alimentos , Frutas/química , Proteínas de Plantas/metabolismo
19.
Food Chem ; 298: 125080, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260985

RESUMO

Propolis extract was investigated as potential substitute for sorbate in orangeade. Extract was prepared by using aqueous solution of hydroxypropyl-beta-cyclodextrins. Propolis extract was incorporated in non-carbonated orange soft drinks and its antioxidant activity, microbiological stability and color changes were estimated and compared to those of orangeade containing potassium sorbate. l-Ascorbic acid (AsA) degradation at concentrations 0.13 and 1.3% w/w was investigated in the presence of propolis during storage using High Performance Liquid Chromatography-Ion Exclusion Column (HPLC-IEC). The results indicate that the rate of degradation decreased with an increase in ascorbic acid concentration, while addition of propolis affected the degradation rate of samples containing a high AsA concentration. The antifungal effect of propolis extract, potassium sorbate and their combination was assayed. Results showed the inhibition of Aspergillus spp. and B. bruxellensis inhibited in low combined concentrations antimicrobials, while Aspergillus spp. and T. macrosporus were inhibited at 450 mg/g propolis extract.


Assuntos
Bebidas , Conservação de Alimentos/métodos , Conservantes de Alimentos/química , Própole/química , Anti-Infecciosos , Antifúngicos/farmacologia , Antioxidantes/química , Ácido Ascórbico/análise , Ácido Ascórbico/química , Aspergillus/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão/métodos , Cor , Microbiologia de Alimentos , Extratos Vegetais/química , Própole/farmacologia , Ácido Sórbico/farmacologia
20.
Int J Food Microbiol ; 305: 108257, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31276954

RESUMO

Freezing vegetables requires pre-treatments to reduce microbial load and destroy enzymes that impair the frozen product quality. So far blanching has been the most effective pre-treatment, preferred by the food industry, despite its severity: heating up to temperatures close to 100 °C for 1-3 min causes sensory and texture changes in most horticultural products. Alternative blanching treatments, using UV-C radiation combined with milder thermal treatments or with thermosonication, may improve the quality of the final frozen vegetables. Zucchini (Cucurbita pepo L.), the vegetable under study, has an availability in fresh restricted to a season, needing therefore to be often frozen to be used throughout the year. In this study, its surface was first inoculated with two vegetable contaminants, Enterococcus faecalis and Deinococcus radiodurans cells, which are resistant, respectively, to high temperatures and to radiation and then submitted to several blanching treatments, single or combined, and the effect on these microorganisms reduction was evaluated. As single treatments, water blanching (the control treatment, as it is the blanching treatment traditionally used) was applied up to 180 s at temperatures ranging from 65 to 90 °C, and UV-irradiation applied in continuous. As combined pre-treatments, water blanching combined with UV-C (continuous or in pulses), and thermosonication (20 kHz at 50% of power) combined with UV-C pulses were also studied. The continuous UV-C radiation incident irradiance was 11 W/m2 up to 180 s, and the pulses at incident radiance of 67 W/m2, lasting 3.5 s each (35 pulses). Mathematical modeling of bacterial reduction data was carried out using the Bigelow, the Weibull and Weibull modified models, and estimation of their respective kinetic parameters proved that the latter models presented a better fit below 75 °C. The best results proved to be the combination of water blanching at temperatures as low as 85 °C during <2 min with 25 pulses of UV-C (incident irradiance of 67 W/m2) or thermosonication at 90 °C also combined with UV-C pulses, both resulting in 3 log reductions of both microorganisms under study. These results proved to overcome what industry is requiring so far (a 2 log microbial reduction in 3 min), hence minimizing quality changes of frozen zucchini.


Assuntos
Cucurbita/química , Cucurbita/microbiologia , Deinococcus/fisiologia , Enterococcus faecalis/fisiologia , Conservação de Alimentos/métodos , Verduras/química , Verduras/microbiologia , Carga Bacteriana , Deinococcus/genética , Deinococcus/isolamento & purificação , Enterococcus faecalis/genética , Enterococcus faecalis/isolamento & purificação , Congelamento , Temperatura Ambiente , Água/análise
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