Preservation Of Food Products Research Articles

Chemical Composition and Antimicrobial Activity of the Essential Oils from Three Chemotypes of Origanum vulgare L. ssp. hirtum (Link) Ietswaart Growing Wild in Campania (Southern Italy)

Essential oils obtained from inflorescences of three Origanum vulgare L. ssp. hirtum (Link) Ietswaart samples, growing wild in different locations in Campania (Southern Italy), were analysed. Three chemotypes were found: the first, with a prevalence of carvacrol/thymol; the second, characterized by the prevalence of thymol/α-terpineol; the third, featuring a prevalence of linalyl acetate and linalool. This chemical study attempts to provide a contribution in shedding light on the relationship between chemical composition and biotypes and/or chemotypes in Origanum vulgare ssp. hirtum. The essential oils were also evaluated for their antibacterial activity against 10 selected microorganisms. The data obtained contribute to the future view to use the essential oils as natural preservatives for food products, due to their positive effect on their safety and shelf life.

The Alternative Sigma Factor σLofL. monocytogenesPromotes Growth Under Diverse Environmental Stresses

Listeria monocytogenes are important foodborne pathogens that can cause outbreaks of serious human disease. These organisms frequently colonize and proliferate on preserved food products despite exposure to stress conditions induced by low storage temperatures, inclusion of organic acid-based preservatives, and high osmolarity. To assess alternative sigma factor sigma(L) contributions to such stress resistance of L. monocytogenes, quantitative RT-PCR assays and sigL gene deletion mutagenesis were applied in L. monocytogenes EGDe. Transcription of sigL was significantly induced by growth of EGDe under cold, organic acid, and elevated NaCl salt concentration stress conditions. The growth of a DeltasigL strain exposed to these stress conditions was also found to be significantly impaired in comparison to that of its isogenic wild-type strain. The contribution of sigma(L) to transcription control of cold and NaCl stress adaptation genes, oppA, cspD, and clpP, was also comparatively assessed in DeltasigL and wild-type EGDe cells. Transcription of the oppA gene, which encodes the OppA protein that also promotes L. monocytogenes cold growth, was significantly reduced in cold stress-grown DeltasigL cells compared to levels of the wild-type EGDe strain. These findings therefore suggest important roles of sigma(L) regulatory pathways in facilitating resistance of L. monocytogenes organisms against stress conditions associated with low storage temperatures, exposure to organic acid, and elevated NaCl salt concentrations.

High-performance liquid chromatographic analysis of anthraquinone compounds in the Laurera benguelensis

A high-performance liquid chromatographic (HPLC) method has been developed for the characterization of anthraquinone metabolites in extracts of the lichen Laurera benguelensis. With this method four anthraquinone derivatives 1,8-dihydroxy-3-methoxy-6-methylanthraquinone, 1,8-dihydroxy-3-formyl-6-methoxyanthraquinone, 1,8-dihydroxy-3-hydroxymethyl-6-methoxy-anthraquinone and 1,3,8-trihyroxy-6-methylanthraquinone can be analyzed. Components of lichen were detected by characteristic ultraviolet spectra and relative retention times. This is first report of phytochemical analysis of L. benguelensis. Importance of this research is in recognizing some new source (lichen and its extracts) as a natural emplacement of antioxidants because oxidation with free radicals or autooxidation is big problem for preservation of food products.

Modeling the combined effects of enterocins A and B, lactate, and EDTA on the growth of "Salmonella" at different temperatures

The effects of enterocins A and B (produced by Enterococcus faecium CTC492), lactate, and ethylenediaminetetraacetic acid (EDTA) on the growth of Salmonella were modeled together with temperature using the response surface methodology. Six serovars of Salmonella enterica were inoculated (ca. 10(3) cells/ml) in brain-heart infusion broth with different levels of the studied factors and then incubated at different temperatures. The results showed that while Salmonella growth was affected by all the factors, temperature was the most important factor influencing the time to detection of the pathogen. All factors, including temperature, showed significant two-way interactions. The presence of enterocins A and B, lactate, and EDTA had an inhibitory effect that was enhanced at suboptimal temperatures for growth, thus delaying the time to detection. Moderate-low concentrations of lactate and EDTA increased the inhibitory effect of enterocins A and B. The effectiveness of these bacteriocins was not further enhanced by high concentrations of lactate (>3.6%) or EDTA (>200 mg/l). The mathematical model obtained from these analyses provides a useful tool to assess the effects of natural antimicrobials and their interactions with other growth-related factors on the growth response of Salmonella. The results can be applied to determine the most effective combination of hurdles to be used in the preservation of food products.

Studies on the antimicrobial activities of extracts from Eupatorium lindleyanum DC against food spoilage and food-borne pathogens

Antimicrobial activity of extracts from Eupatorium lindleyanum DC (EEL), a traditional Chinese medicine, was screened against eight selected food spoilage and food-borne pathogens. The EEL was observed to show effective antimicrobial effects with a remarkable dose–response relationship and broad antimicrobial spectrum on all test Gram-positive bacteria and Gram-negative species. Acid environment or medium helps enhance the antimicrobial activity. The activity remains rather stable under conventional food sterilization conditions and normal shelving temperature. The EEL obtained by water decoction exhibited the maximum inhibitory effect on test strains with its MIC (minimum inhibitory concentration) and/or MBC (minimum bactericidal concentration) value of 0.4–0.8 mg ml −1. When the EEL was used in commercial orange juice at a concentration of 0.4 mg ml −1, a similar antimicrobial effect to potassium sorbate at the level of 0.2 mg ml −1 was observed. In conclusion, in addition to use as a functional food ingredient, the EEL may be selected as an inhibitor to preserve food products where a natural preservative is desired.

Microbial fermented tea – a potential source of natural food preservatives

Antimicrobial activities of microbial fermented tea are much less known than its health beneficial properties. These antimicrobial activities are generated in natural microbial fermentation process with tea leaves as substrates. The antimicrobial components produced during the fermentation process have shown inhibitory effects against several food-borne and pathogenic bacteria. With the trend of increasing use of natural and biological preservatives in food products, natural antimicrobial agents from microbial fermented tea may offer an innovative and interesting measure for such applications. However, a breakthrough in this field can only be realised after several critical aspects are clarified and further studied. Only then, the application of these potential, novel and natural antimicrobial substances from microbial fermented tea can be industrialized. The present review describes some unique microbial fermentation of tea and the antimicrobial activities formed during the fermentation process. Moreover, future needs in research and development of these antimicrobial compounds from microbial fermentation of tea are discussed for potential industrial applications.

Extracellular Production of a Novel Ice Structuring Protein by Bacillus subtilis—a Case of Recombinant Food Peptide Additive Production

Bacillus subtilis is an ideal host for the production of extracellular heterologous proteins. Antifreeze protein (ice structuring protein, ISP) is a potent additive in cryogenic preservation of food products. In this investigation, the first production of a recombinant ISP was achieved by using a high-efficient artificial promoter and a signal peptide from subtilisin YaB. The functional ISP was expressed extracellularly at a high level by a protease deficient host, B. subtilis WB800. This study provides an efficient tool to produce recombinant food peptide additive at a high level and overcomes the problem of natural resources limitation as well.

High pressure versus heat treatments for pasteurisation and sterilisation of model emulsions

Heat treatments can have considerable influence on the droplet size distribution of oil-in-water emulsions. In the present study, high-pressure (HP) pasteurisation and sterilisation were evaluated as alternatives for heat preservation of emulsions. HP conditions used were 600 MPa, 5 min, room temperature and 800 MPa, 5 min, 80 °C initial temperature, 115 °C maximum temperature for HP pasteurisation and HP sterilisation respectively. The effects on droplet size of these conditions were compared to heat treatments for whey protein isolate (WPI) and soy protein isolate (SPI) emulsions at two pH values and two ionic strengths. For WPI, also the effect of protein in the bulk phase was evaluated. Both HP and heat pasteurisation treatments resulted in similar or slightly decreased average droplet sizes compared to the untreated samples. For neutral SPI emulsions, heat sterilisation increased the average droplet size from 1.6 μm to 43.7 μm, while HP sterilisation resulted only in a small increase towards an average droplet size of 2.1 μm. The neutral WPI emulsions, except those with a high ionic strength, gave similar results with respect to the droplet size, showing that for neutral pH WPI or SPI emulsions HP sterilisation is preferable above heat sterilisation. Concerning the low pH WPI emulsions, the droplet sizes were unaffected after both heat and HP sterilisation. Heat pasteurisation and sterilisation are effective treatments to preserve food products that are based on emulsions with respect to microbial safety. However, heat treatments can negatively affect emulsion stability. Currently, in addition to high pressure at room temperature, high-pressure treatments at elevated temperature received a great deal of interest to achieve sterilised products. This study evaluated the effects of both heat and high-pressure pasteurisation and sterilisation on droplet size of whey protein isolate and soy protein isolate emulsions. It was shown that for pasteurisation treatments, both heat and high pressure have minor effects on the droplet size of the emulsion. However, for sterilisation purposes high-pressure treatment is preferable for emulsion at neutral pH. High-pressure sterilisation can therefore be interesting alternatives to heat treatments to preserve emulsion stability.

Впровадження технологiй радіаційної пастеризації та консервацiї продуктiв харчування

Впровадження технологiй радіаційної пастеризації та консервацiї продуктiв харчування

Technical note - effects of seaming conditions on external and internal double-seam characteristics in round metal cans

Canning is the major packaging technology for fully preserved food products. To obtain safe canned foods with extended shelf-life, the closed cans have to be hermetic. The consistency and quality of the seaming process are crucial to food safety. This note investigates the effects of different seaming conditions (base-plate pressure and seaming-roller pressure) on external (seam thickness, seam height) and internal (body hook length, overlap, lid hook length, seam gap and body hook butting) double-seam characteristics in round metal cans. External double-seam characteristics were significantly affected by the seaming-roller pressure during the final closure of the cans. Generally, there were small effects of base-plate pressure on the external double-seam characteristics. In contrast, all the investigated double-seam characteristics were affected significantly by the seaming-roller pressure, whereas only body hook length and seam gap were significantly affected by the base-plate pressure. This note illustrates the importance of close control and optimization of the seaming conditions during production of canned foods as a means to reduce the processing induced variability in double-seam characteristics, and subsequently to obtain safe and high-quality canned products. Copyright © 2005 John Wiley & Sons, Ltd.

Effects of butylated hydroxyanisole on the development and functions of reproductive system in rats

Butylated hydroxyanisol (BHA) is a widely used antioxidant for long preservation of food products, cosmetics and pharmaceuticals. Although BHA is generally recognized as safe, it is classified as a suspected endocrine-disrupting compound. We investigated the effects of BHA on reproductive function and development by the treatment of mature male and female SD rats (F0) through pre-gestation, gestation and lactation period and of their offspring (F1) until 13 weeks old via gavage with BHA 0 (corn oil, vehicle control), 10, 100 and 500 mg/kg bw/day. Organ weights of liver, adrenal gland and thyroid gland of F0 rats were increased by BHA 500 mg/kg but those of spleen and ventral prostate were decreased without significant difference in terminal body weight. Reduced serum testosterone and thyroxine (T4) were observed with dose-dependent manner in F0 male rats. Mating rate was decreased and cohabitation duration for conception was longer without differences in the number, motility and morphology of sperm by BHA 500 mg/kg. Body weight of F1 offspring was significantly decreased with change of relative weight of liver and brain by BHA 500 mg/kg at PND21. Sexual maturation indicated by vaginal opening and preputial separation was delayed by BHA 500 mg/kg. The weights of liver and adrenal gland were increased while those of spleen, vagina, testes and ventral prostate were decreased in F1 rats exposed to BHA 100 or 500 mg/kg for 13 weeks. Also, BHA 500 mg/kg reduced the velocity of sperm motion and number with smaller-sized sperm head in F1 male rats and slightly shortened estrous cycle length with higher frequency of estrus and lower frequency of diestrus stages in F1 female rats. Lower serum T4 and testosterone contents with higher serum cholesterol levels were also observed by BHA 500 mg/kg. Increased follicular cell height, and exfoliated and vacuolated follicular epithelial cells were observed in thyroids of F1 female and males rats exposed to BHA 500 mg/kg. This study elucidates that high dose of BHA induce weak dysfunction and underdevelopment of reproductive system of male and female rats with the change of T4 and testosterone levels, sex organ weights and sexual maturation and histological lesions of thyroid gland.

Development of polythene films for food packaging activated with an antilisterial bacteriocin from Lactobacillus curvatus 32Y.

The aims of this work were to (i) use a bacteriocin produced by Lactobacillus curvatus 32Y active against Listeria monocytogenes to activate polythene films by different methods, (ii) implement a large-scale process for antilisterial polythene films production and (iii) verify the efficacy of the developed films in inhibiting the growth of L. monocytogenes during the storage of meat products. The film was made active by using the antilisterial bacteriocin 32Y by Lact. curvatus with three different procedures: soaking, spraying and coating. The antimicrobial activity of the activated films was tested in plate assays against the indicator strain L. monocytogenes V7. All the used procedures yielded active polythene films although the quality of the inhibition was different. The coating was therefore employed to develop active polythene films in an industrial plant. The antimicrobial activity of the industrially produced films was tested in experiments of food packaging involving pork steak and ground beef contaminated by L. monocytogenes V7 at roughly 10(3) CFU cm(-2) and gram respectively. The results of the challenge tests showed the highest antimicrobial activity after 24 h at 4 degrees C, with a decrease of about 1 log of the L. monocytogenes population. Antimicrobial packaging can play an important role in reducing the risk of pathogen development, as well as extending the shelf life of foods. Studies of new food-grade bacteriocins as preservatives and development of suitable systems of bacteriocin treatment of plastic films for food packaging are important issues in applied microbiology and biotechnology, both for implementing and improving effective hurdle technologies for a better preservation of food products.

Application of heat transfer analysis for frozen food storage caverns

Supply of high quality preserved food products has always been very important. Storage of food in underground caverns is superior over food storage tanks constructed at surface from an energy conservation point of view. There are a lot of underground openings excavated in tuff used for the storage of fruits and vegetables at the Cappadocia Region of Turkey. However, there has not been any attempt to use these underground openings for deep frozen food storage and related heat transfer details. The main purpose of this work was to investigate underground food storage openings in the Cappadocia Region and their potential use for frozen food storage. Details of heat transfer around openings for various geometrics in three-dimensional have been modelled by using a finite element software package called MARC. For the sake of comparison, heat transfer details around a similar opening excavated in granite were also determined. A comparison of underground caverns excavated in tuff and granite with a surface deep freeze storage tank was also made by both taking construction and operational costs into account. Construction of an underground deep freeze storage cavern excavated in tuff would cost one half of a same size surface tank whereas, energy loss due to heat transfer is three times lower in the favour of underground storage cavern opened in tuff.

Antioxidant activities of grape (Vitis vinifera) pomace extracts.

Antioxidant-rich fractions were extracted from grape (Vitis vinifera) pomace using ethyl acetate, methanol, and water. The extracts were screened for their potential as antioxidants in different models. The ethyl acetate, methanol, and water extracts showed 76, 87.1, and 21.7% antioxidant activities at 100 ppm, respectively, using the 1,1-diphenyl-2-picrylhydrazyl model system. As the methanol extract of grape pomace showed maximum antioxidant activity among all of the extracts, it was selected to determine its effect on lipid peroxidation, hydroxyl radical scavenging activity, and human low-density lipoprotein (LDL) oxidation. The methanol extract showed 71.7, 73.6, and 91.2% inhibition using the thiobarbituric acid method, hydroxyl radical scavenging activity, and LDL oxidation, respectively, at 200 ppm. Treatment of albino rats of the Wistar strain with a single dose of CCl(4) at 1.25 mL/kg of body weight decreases the activities of catalase, superoxide dismutase (SOD), and peroxidase by 81, 49, and 89%, respectively, whereas the lipid peroxidation value increased nearly 3-fold. Pretreatment of the rats with the methanolic extract of grape pomace at 50 mg/kg (in terms of catechin equivalents) followed by CCl(4) treatment causes restoration of catalase, SOD, and peroxidase by 43.6, 73.2, and 54%, respectively, as compared with control, whereas lipid peroxidation was restored to values comparable with the control. Histopathological studies of the liver of different groups also support the protective effects exhibited by the methanol extract of grape pomace by restoring the normal hepatic architecture. Owing to this property, the studies on grape pomace can be further extended to exploit its possible application for the preservation of food products as well as a health supplement and neutraceutical.

Studies on the Antioxidant Activity of Pomegranate (Punica granatum) Peel and Seed Extracts Using in Vitro Models

Antioxidant-rich fractions were extracted from pomegranate (Punica granatum) peels and seeds using ethyl acetate, methanol, and water. The extracts were screened for their potential as antioxidants using various in vitro models, such as beta-carotene-linoleate and 1,1-diphenyl-2-picryl hydrazyl (DPPH) model systems. The methanol extract of peels showed 83 and 81% antioxidant activity at 50 ppm using the beta-carotene-linoleate and DPPH model systems, respectively. Similarly, the methanol extract of seeds showed 22.6 and 23.2% antioxidant activity at 100 ppm using the beta-carotene-linoleate and DPPH model systems, respectively. As the methanol extract of pomegranate peel showed the highest antioxidant activity among all of the extracts, it was selected for testing of its effect on lipid peroxidation, hydroxyl radical scavenging activity, and human low-density lipoprotein (LDL) oxidation. The methanol extract showed 56, 58, and 93.7% inhibition using the thiobarbituric acid method, hydroxyl radical scavenging activity, and LDL oxidation, respectively, at 100 ppm. This is the first report on the antioxidant properties of the extracts from pomegranate peel and seeds. Owing to this property, the studies can be further extended to exploit them for their possible application for the preservation of food products as well as their use as health supplements and neutraceuticals.

Membrane permeabilization in relation to inactivation kinetics of Lactobacillus species due to pulsed electric fields.

Membrane permeabilization due to pulsed electric field (PEF) treatment of gram-positive Lactobacillus cells was investigated by using propidium iodide uptake and single-cell analysis with flow cytometry. Electric field strength, energy input, treatment time, and growth phase affected membrane permeabilization of Lactobacillus plantarum during PEF treatment. A correlation between PEF inactivation and membrane permeabilization of L. plantarum cells was demonstrated, whereas no relationship was observed between membrane permeabilization and heat inactivation. The same results were obtained with a Lactobacillus fermentum strain, but the latter organism was more PEF resistant and exhibited less membrane permeabilization, indicating that various bacteria have different responses to PEF treatment. While membrane permeabilization was the main factor involved in the mechanism of inactivation, the growth phase and the acidity of the environment also influenced inactivation. By using flow cytometry it was possible to sort cells in the L. plantarum population based on different cell sizes and shapes, and the results were confirmed by image analysis. An apparent effect of morphology on membrane permeabilization was observed, and larger cells were more easily permeabilized than smaller cells. In conclusion, our results indicate that the ability of PEF treatment to cause membrane permeabilization is an important factor in determining inactivation. This finding should have an effect on the final choice of the processing parameters used so that all microorganisms can be inactivated and, consequently, on the use of PEF treatment as an alternative method for preserving food products.

Antioxidant activity of grape seed (Vitis vinifera) extracts on peroxidation models in vitro

Antioxidant-rich fractions were extracted from grape seeds (Vitis vinifera) using various solvents, such as acetone, ethyl acetate, methanol and mixtures of different solvents, such as ethyl acetate (EtOAc) and water in 9:1, 17:3 and 4:1 ratios. The antioxidant activity of the extracts was evaluated using a β-carotene-linoleate model system and linoleic acid peroxidation method. At 100 ppm concentration, various extracts showed 65–90% antioxidant activity. Mixtures of EtOAc and water at different concentrations exhibited more antioxidant activity than other extracts. These extracts also showed good reducing power, at 500 μg/ml concentration, by the potassium ferricyanide reduction method. Grape seed extracts may be exploitable for the preservation of food products as well as for health supplements and nutraceuticals.

Critical factors determining inactivation kinetics by pulsed electric field food processing

The potential to commercialize the non-thermal pulsed electric field (PEF) technology as a new method to preserve food products has caught the attention of the food industry that wishes to fulfil consumers demands for fresh products. In recent years, numerous research groups have demonstrated the possibility to inactivate a range of microorganisms both in buffer systems and in food products using different PEF systems. In this review, we survey the critical process factors and main characteristics of food products that determine the microbial inactivation kinetics.

Combined industrial processes with irradiation to assure innocuity and preservation of food products — a review

The desire to assure food safety for consumption requires better food preservation techniques. The presence of parasites, insects, mites, and micro-organisms, is an important source of problems. In this regard, irradiation is an interesting alternative to be considered to satisfy quarantine requirements, to control severe losses during transportation and commercialization, and to insure food safety. This paper reviews some potential applications of irradiation for preserving food products.

Antimicrobial screening of some Indian spices.

In India, spices have been traditionally used since ancient times, for the preservation of food products as they have been reported to have antiseptic and disinfectant properties. In this respect, a preliminary screening for antimicrobial activities of 35 different Indian spices has been carried out. Of the spices surveyed, the results indicate that clove, cinnamon, bishop's weed, chilli, horse raddish, cumin, tamarind, black cumin, pomegranate seeds, nutmeg, garlic, onion, tejpat, celery, cambodge, have potent antimicrobial activities against the test organisms Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC 10536) and Saccharomyces cerevisiae (ATCC 9763). The results also establish the traditional use of spices as food preservatives, disinfectants and antiseptics.