Preservation Of Fruit Juices Research Articles

Chemical composition, in vitro anti-yeast activity and fruit juice preservation potential of lemon grass oil

The anti-yeast activity of lemon grass oil was evaluated against several food spoiling yeasts (Saccharomyces cerevisiae, Zygosaccharomyces bailii, Aureobasidium pullulans, Candida diversa, Pichia fermentans, Pichia kluyveri, Pichia anomala and Hansenula polymorpha) through disc diffusion and microbroth dilution method. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) varied from 0.28 to 1.3 mg/ml and 0.56 to 4.5 mg/ml, respectively, where highest MIC (2.25 mg/ml) was shown by A. pullulans and lowest MIC (0.28 mg/ml) was shown by C. diversa and P. anomala. Kill time assay was conducted for selected three yeast strains where S. cerevisiae showed highest reduction (3 log cfu) in viability within 24 h exposure of lemon grass oil at MFC level. Further, the anti-yeast efficacy of lemon grass oil alone and in combination with thermal treatment was evaluated in real food system i.e. mixed fruit juices. Chemical composition analysis of lemon grass oil by gas chromatography–mass spectrometry (GC–MS) revealed that the dominant compounds were geranial (40.5%), neral (30.7%), geranyl acetate (5.1%), caryophyllene (2.5%). Present results established the superior performance of integrated (thermal–lemon grass oil) treatment over the individual exposure (lemon grass oil or thermal treatment alone) for fruit juice preservation.

Emerging preservation techniques for controlling spoilage and pathogenic microorganisms in fruit juices.

Fruit juices are important commodities in the global market providing vast possibilities for new value added products to meet consumer demand for convenience, nutrition, and health. Fruit juices are spoiled primarily due to proliferation of acid tolerant and osmophilic microflora. There is also risk of food borne microbial infections which is associated with the consumption of fruit juices. In order to reduce the incidence of outbreaks, fruit juices are preserved by various techniques. Thermal pasteurization is used commercially by fruit juice industries for the preservation of fruit juices but results in losses of essential nutrients and changes in physicochemical and organoleptic properties. Nonthermal pasteurization methods such as high hydrostatic pressure, pulsed electric field, and ultrasound and irradiations have also been employed in fruit juices to overcome the negative effects of thermal pasteurization. Some of these techniques have already been commercialized. Some are still in research or pilot scale. Apart from these emerging techniques, preservatives from natural sources have also shown considerable promise for use in some food products. In this review article, spoilage, pathogenic microflora, and food borne outbreaks associated with fruit juices of last two decades are given in one section. In other sections various prevention methods to control the growth of spoilage and pathogenic microflora to increase the shelf life of fruit juices are discussed.

Eucalyptus essential oil as a natural food preservative: in vivo and in vitro antiyeast potential.

In this study, the application of eucalyptus essential oil/vapour as beverages preservative is reported. The chemical composition of eucalyptus oil was determined by gas chromatography-mass spectrometry (GC-MS) and solid phase microextraction GC-MS (SPME/GC-MS) analyses. GC-MS revealed that the major constituents were 1,8-cineole (80.5%), limonene (6.5%), α-pinene (5%), and γ-terpinene (2.9%) while SPME/GC-MS showed a relative reduction of 1,8-cineole (63.9%) and an increase of limonene (13.8%), α-pinene (8.87%), and γ-terpinene (3.98%). Antimicrobial potential of essential oil was initially determined in vitro against 8 different food spoilage yeasts by disc diffusion, disc volatilization, and microdilution method. The activity of eucalyptus vapours was significantly higher than the eucalyptus oil. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) varied from 0.56 to 4.50 mg/mL and from 1.13 to 9 mg/mL, respectively. Subsequently, the combined efficacy of essential oil and thermal treatment were used to evaluate the preservation of a mixed fruit juice in a time-dependent manner. These results suggest eucalyptus oil as a potent inhibitor of food spoilage yeasts not only in vitro but also in a real food system. Currently, this is the first report that uses eucalyptus essential oil for fruit juice preservation against food spoiling yeast.

Pulsed Electric Field Processing of Orange Juice: A Review on Microbial, Enzymatic, Nutritional, and Sensory Quality and Stability.

During the last decades pulsed electric field (PEF) processing received considerable attention due to its potential to enhance food products or create alternatives to conventional methods in food processing. It is generally acknowledged that PEF processing can deliver safe and chill-stable fruit juices with fresh-like sensory and nutritional properties. Relatively low-processing temperature and short residence times can achieve highly effective inactivation of microorganisms while retaining product quality. A first commercial application of PEF for preservation of fruit juices was launched in 2006 in the United States. Since then, industrial-scale processing equipment for liquid and solid products were developed and, in Europe in 2009, an industrial juice preservation line was installed using 20 kV/cm pulses at 40 to 50 °C to extend the chill-stability of fruit juices, including citrus juices and smoothies, from 6 to 21 d. The related PEF processing costs are in the range of US $0.02 to 0.03 per liter and are justified due to access to new markets and reduced return of spoiled product. However, despite its commercial success there are still many unknown factors associated with PEF processing of fruit and citrus juices and many conflicting reports in the literature. This literature review, therefore, aims to provide a comprehensive overview of the current scientific knowledge of PEF effects on microbial, enzymatic, nutritional, and sensory quality and stability of orange juices.

Characterization of bacteriocin bificin C6165: a novel bacteriocin

To purify and primarily characterize an anti-Alicyclobacillus bacteriocin produced by Bifidobacterium animalis subsp. animalis CICC 6165, suggested to be named bificin C6165. During purification of the bificin C6165, optimal recovery was achieved with ammonium sulfate precipitation followed by two chromatographic steps. Mass spectrometry analyses revealed a distinctive peak corresponding to a molecular mass of 3395·1 Da. This bacteriocin was heat stable, effective after refrigerated storage and freeze-thaw cycles. The primary mode of action of bificin C6165 is most probably due to pore formation, as indicated by the efflux of K(+) from metabolically active cells of Alicyclobacillus acidoterrestris. In the presence of 10 mmol l(-1) gadolinium, bificin C6165 did not affect cells of Alicyclobacillus acidoterrestris. This suggests that the mode of action of bificin C6165 relies on a net negatively charged cell surface. Bificin C6165 is indeed a novel bacteriocin and it exhibited remarkable potency for Alicyclobacillus control. Application of bacteriocins in preservation of fruit juices has seldom been studied. Bificin C6165 may be an alternative method to control juice spoilage by this Alicyclobacillus acidoterrestris and meet increasing consumer demand for nature and artificial chemical additive-free food products.

Synergistic combinations of high hydrostatic pressure and essential oils or their constituents and their use in preservation of fruit juices

This work addresses the inactivation achieved with Escherichia coli O157:H7 and Listeria monocytogenes EGD-e by combined processes of high hydrostatic pressure (HHP) and essential oils (EOs) or their chemical constituents (CCs). HHP treatments (175–400MPa for 20min) were combined with 200μL/L of each EO (Citrus sinensis L., Citrus lemon L., Citrus reticulata L., Thymus algeriensis L., Eucalyptus globulus L., Rosmarinus officinalis L., Mentha pulegium L., Juniperus phoenicea L., and Cyperus longus L.) or each CC ((+)-limonene, α-pinene, β-pinene, p-cymene, thymol, carvacrol, borneol, linalool, terpinen-4-ol, 1,8-cineole, α-terpinyl acetate, camphor, and (+)-pulegone) in buffer of pH 4.0 or 7.0. The tested combinations achieved different degrees of inactivation, the most effective being (+)-limonene, carvacrol, C. reticulata L. EO, T. algeriensis L. EO and C. sinensis L. EO which were capable of inactivating about 4–5 log10 cycles of the initial cell populations in combination with HHP, and therefore showed outstanding synergistic effects. (+)-Limonene was also capable of inactivating 5 log10 cycles of the initial E. coli O157:H7 population in combination with HHP (300MPa for 20min) in orange and apple juices, and a direct relationship was established between the inactivation degree caused by the combined process with (+)-limonene and the occurrence of sublethal injury after the HHP treatment. This work shows the potential of EOs and CCs in the inactivation of foodborne pathogens in combined treatments with HHP, and proposes their possible use in liquid food such as fruit juices.

Anti-yeast activity of mentha oil and vapours through in vitro and in vivo (real fruit juices) assays

The anti-yeast activity of mentha oil and vapours was evaluated against 8 food spoiling yeasts through disc diffusion, disc volatilisation and micro broth dilution method. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) varied from 0.28 to 2.25 and 1.13 to 4.5mg/ml, respectively. Furthermore, the anti-yeast efficacy of mentha oil alone and in combination with thermal treatment was evaluated in a real food system i.e. mixed fruit juices. The samples treated with a combination of mentha oil at the MIC, ½ MIC and ¼ MIC levels and thermal treatment enhanced the reduction viability. Chemical characterisation of mentha oil by gas chromatography-mass spectrometry (GC–MS) revealed that the dominant compounds were cis-menthone (27.43%), menthol (24.3%), trans-menthone (9.23%), limonene (5.84%), menthofuran (4.44%) and isomenthol (3.21%). Present results established the superior performance of integrated treatment over individual exposure for fruit juice preservation.

Combined Use of Ultrasound and Natural Antimicrobials To Inactivate Listeria monocytogenes in Orange Juice

The presence of Listeria monocytogenes could seriously affect the safety of nonpasteurized fruit juices. High-intensity ultrasound combined with mild heat treatment and natural antimicrobials may be an alternative technology for fruit juice preservation. The response of L. monocytogenes in orange juice to combined treatments involving moderate temperature (45°C), high-intensity ultrasound (600 W, 20 kHz, 95.2-μm wave amplitude), and the addition of different levels of vanillin (0, 1,000, 1,500, and 2,000 ppm), citral (0, 75, and 100 ppm), or both was investigated to find the most effective inactivation treatment. Nonlinear semilogarithmic survival curves were successfully fitted by the Weibull model. The presence of vanillin or citral greatly increased the bactericidal effect of thermosonication and changed the distribution of inactivation times. When both antimicrobials were added together and ultrasound was applied, narrowest frequency shapes, skewed to the right, with low variances and death time means between 1.6 and 2.6 min, were obtained. Orange juices with 1,500 or 1,000 ppm of vanillin and 100 ppm of citral were pleasant for the consumers.

Effects of Cymbopogon citratus L. essential oil on the growth, morphogenesis and aflatoxin production of Aspergillus flavus ML2‐strain

The mycelial growth of Aspergillus flavus Link was completely inhibited using 1.5 (microl/ml or 2.0 (microl/ml of Cymbopogon citratus essential oil applied by fumigation or contact method in Czapek's liquid medium, respectively. This oil was found also to be fungicidal at the same concentrations. The sublethal doses 1.0 and 1.5 (microl/ml inhibited about 65% of fungal growth after five days of incubation and delayed conidiation as compared with the control. Microscopic observations using Light Microscope (LM), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) were carried out to determine the ultra structural modifications of A. flavus hyphae after treatment with C. citratus essential oil. The hyphal diameter decreased and hyphal wall appeared as precipitates and disappeared in some regions. This oil also caused plasma membrane disruption and mitochondrial structure disorganization. Moreover, Ca(+2), K(+) and Mg(+2) leakages increased from the fumigated mycelium and its total lipid content decreased, while the saturated and unsaturated fatty acids increased. One of the most important results obtained during this study was the ability of C. citratus essential oil at its sublethal dose to completely inhibit aflatoxin B(1) production from A. flavus. These findings increase the possibility of exploiting C. citratus essential oil as an effective inhibitor of biodegradation and storage contaminating fungi and also in fruit juice preservation.

Effects of Cymbopogon citratus L. essential oil on the growth, lipid content and morphogenesis of Aspergillus niger ML2‐strain

The mycelial growth of Aspergillus niger van Tieghem was completely inhibited using 1.5 (microl/ml or 2.0 (microl/ml of Cymbopogon citratus essential oil applied by fumigation or contact method in Czapek liquid medium, respectively. This oil was found also to be fungicidal at the same concentrations. The sublethal doses 1.0 and 1.5 (microl/ml inhibited about 70% of fungal growth after five days of incubation and delayed conidiation as compared with the control. Microscopic observations using Light Microscope (LM), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) were carried out to determine the ultra structural modifications of A. niger hyphae after treatment with C. citratus essential oil. The hyphal diameter and hyphal wall appeared markedly thinner. This oil also caused plasma membrane disruption and mitochondrial structure disorganization. Moreover, Ca+2, K+ and Mg+2 leakages increased from the fumigated mycelium and its total lipid content decreased, while the saturated fatty acids decreased and unsaturated fatty acids increased. These findings increase the possibility of exploiting C. citratus essential oil as an effective inhibitor of biodegrading and storage contaminating fungi and in fruit juice preservation.

Microbial Stability of Mango (Mangifera indica L.) Juice Preserved by Combined Application of Mild Heat and Extracts of Two Tropical Spices

The microbial stability of mango (Mangifera indica L.) juice (pH 4.9) supplemented with extracts of ginger (Zingiber officinale) and nutmeg (Myristica fragrans) was investigated during 3 months of ambient-temperature storage. Heating at 55°C for 15 min markedly reduced the levels of non-spore-forming bacteria and produced a product with acceptable taste. Supplementing mango juice with an agueous extract of ginger (15%, vol/vol) or nutmeg (20%, vol/vol) inhibited the growth of challenge microorganisms, but produced a product with unacceptable taste. Heating the mango juice at 55°C for 15 min and supplementing with nutmeg (4%, vol/vol) and ginger (4%, vol/vol) markedly inhibited microbial growth and produced a product with acceptable taste. Tropical spices may prove useful in preservation of fruit juices by hurdle technology.

Combination of irradiation with mild heat treatment

In the case of fungi, heat treatment preceding irradiation usually results in a greater antimicrobial effect of the combination process compared with heating after irradiation. The usefulness of mild heat treatment prior to low-dose irradiation has been demonstrated for extending the shelf-life of certain fruits and cereal products, preservation of fruit juices and some other processed fruit products, and for inactivation of toxigenic moulds on nuts, dried fruits, cocoa beans and maize. With bacterial sproes, pre-irradiation followed by heating proved to be synergistic. This combination may be utilized for preservation of foods where heat resistance of bacterial spores is a critical factor. The radiation-damaged bacterial spores in irradiated dry food ingredients have been shown to be more easily destroyed by normal heat processing of complex foods containing such ingredients. In specific cases simultaneous application of heat and radiation (thermoradiation) might be considered for an enhanced destruction of microbes. Thermal stress can also complement or potentiate the effectiveness of radiation disinfestation.

Radiation preservation of fruit juices in combination with freeze-concentration

Juice was obtained of fresh strawberries, apples and grapes. The juice was clarified and then cryoconcentrated to different water activities (0·96-0·87). A 60Co radiation source was used for treatment. The samples were stored at 20–22°C. The storage life, colour and sensory quality of the samples were studied as a function of radiation dose and water activity. It was established that a cryoconcentrate of 0·90–0·92 water activity when treated with 0·8–1·3 Mrad, dependent on the initial cell count, may be considered microbiologically stable at a storage temperature of 20–22°C and its organoleptic quality is satisfactory.

Control of Quality in Fruit Products

Recent advances in our knowledge of nutrition have brought home the importance of fruits in a balanced diet. Fruits with their valuable vitamins and minerals are essential to man for maintaining good health. Unfortunately fruits, being highly seasonal, are subject to spoilage during periods of glut while they cannot be easily obtained during other parts of the year. Advances in food technology have, however, enabled us to preserve fruits in all their richness and flavour and make them available during any part of the year, and in any place by methods such as (1) Canning or bottling, (2) Preservation of fruit juices in the form of squashes, syrups, and cordials, (3) Conversion of fruit into jams, jellies, preserves and candies, (4) Dehydration and (5) Cold storage and freezing otc.

Heat penetration in the pasteurizing of syrups and concentrates in glass containers

does not appear. First page follows. Introduction The enforcement of the food and drug laws during the past decade has had a marked influence on the methods used for the preservation of fruit juices and syrups. Chemical preservatives, at one time very generally used, have been to a large extent replaced by pasteurization. The only chemical preservatives permitted by law are. sodium-benzoate and sulfur-dioxide. Used in moderate concentrations these preservatives are considered not injurious. to health; but the consuming public has reacted unfavorably toward them in recent years, largely because they affect the flavor of the product adversely. Since pasteurization is the method best suited to the preservation of these beverages, it is very desirable that accurate information regarding the factors affecting this operation should be available. Pasteurization is that process of food preservation in which the food is heated to a temperature sufficient to destroy or inhibit the growth of any microorganisms that would affect the food injuriously, but not necessarily to destroy all the living microorganisms with which the food may be infected. In the pasteurization of fruit juices, beverages, and syrups, the time and temperature of heating must be such as to destroy the yeasts and molds the activity of which would cause deterioration of the product.