Food Preservation Methods Research Articles

Control strategies for defrost and evaporator fans operation in walk-in freezers

Heat removal is the most extended method for food preservation in food manufacturing industry by lowering food temperatures to stop microorganisms growing, which might spoil the product and could cause toxicity. Therefore, walk-in freezers are used for that purpose consuming a relevant part of the energy on service sector. The compression refrigeration system of the walk-in freezers can be blocked by the frost accumulated on the evaporator. For that reason a defrost process, which requires an important part of the energy consumption, has to be launched from time to time. In this paper, the schedule which manages the defrost process is investigated to limit its activation only when it is necessary. Moreover, different fan operation strategies were tested regarding the energy efficiency of the whole refrigeration system. This study has provided a system control strategy both for defrost and fans operation, depending on the frost built up on the evaporator. The control improves the energy performance of the whole refrigeration system.

Novel Biocontrol Methods for Listeria monocytogenes Biofilms in Food Production Facilities.

High mortality and hospitalization rates have seen Listeria monocytogenes as a foodborne pathogen of public health importance for many years and of particular concern for high-risk population groups. Food manufactures face an ongoing challenge in preventing the entry of L. monocytogenes into food production environments (FPEs) due to its ubiquitous nature. In addition to this, the capacity of L. monocytogenes strains to colonize FPEs can lead to repeated identification of L. monocytogenes in FPE surveillance. The contamination of food products requiring product recall presents large economic burden to industry and is further exacerbated by damage to the brand. Poor equipment design, facility layout, and worn or damaged equipment can result in Listeria hotspots and biofilms where traditional cleaning and disinfecting procedures may be inadequate. Novel biocontrol methods may offer FPEs effective means to help improve control of L. monocytogenes and decrease cross contamination of food. Bacteriophages have been used as a medical treatment for many years for their ability to infect and lyse specific bacteria. Endolysins, the hydrolytic enzymes of bacteriophages responsible for breaking the cell wall of Gram-positive bacteria, are being explored as a biocontrol method for food preservation and in nanotechnology and medical applications. Antibacterial proteins known as bacteriocins have been used as alternatives to antibiotics for biopreservation and food product shelf life extension. Essential oils are natural antimicrobials formed by plants and have been used as food additives and preservatives for many years and more recently as a method to prevent food spoilage by microorganisms. Competitive exclusion occurs naturally among bacteria in the environment. However, intentionally selecting and applying bacteria to effect competitive exclusion of food borne pathogens has potential as a biocontrol application. This review discusses these novel biocontrol methods and their use in food safety and prevention of spoilage, and examines their potential to control L. monocytogenes within biofilms in food production facilities.

The effectiveness of radiant catalytic ionization in inactivation ofListeria monocytogenesplanktonic and biofilm cells from food and food contact surfaces as a method of food preservation

The aim of the study was to evaluate the microbicidal effectiveness of radiant catalytic ionization (RCI) against Listeria monocytogenes strains in the form of planktonic cells and biofilm on food products and food contact surfaces as a method of food preservation. The study material comprised six strains of L.monocytogenes, isolated from food. Samples of different types of food available by retail (raw carrot, frozen salmon filets, soft cheese) and the fragments of surfaces (stainless steel AISI 304, rubber, milled rock tiles, polypropylene) were used in the experiment. The obtained results showed the effectiveness of RCI in the inactivation of both forms of the tested L. monocytogenes strains on all the surfaces. The effectiveness of RCI for biofilm forms was lower as compared with planktonic forms. The PRR value ranged from 18·19 to 99·97% for planktonic form and from 3·92 to 70·10% for biofilm. The RCI phenomenon induces the inactivation of L.monocytogenes on surfaces of food and materials used in the processing industry to a varying degree, depending on the manner of surface contamination, the properties of the contaminated materials as well as on the origin of the strain and the properties of surrounding dispersive environment in which the micro-organisms were suspended. Searching of new actions aimed at the reduction of the microbial contamination of food and food contact surfaces are extremely important. RCI method has been already described as an effective technique of microbial and abiotic pollution removal from air. However, our studies provide new, additional data related to evaluation the RCI efficacy against microbes on different surfaces, both in planktonic and biofilm form.

Quality and postharvest-shelf life of cold-stored strawberry fruit as affected by gum arabic (Acacia senegal ) edible coating

The impact of gum arabic (GA) (10 and 15% w/v) on the quality and postharvest-shelf life of strawberry at storage condition of 4 ± 1°C for 10 days were evaluated. Significant (p < .05) differences were found for the overall 15% GA-coating as compared with the control. The application of GA-coatings maintained the total contents of phenolic, anthocyanin and total soluble solid (TSS) but significantly (p < .05) retarded the increase in polyphenol oxidase (PPO) activity, reduced weight loss, and completely inhibited fungal infections. Moreover, the 15% GA edible coating retained the color, improved the firmness, and increased antioxidant activity compared with control. Likewise, sensory analysis results also showed the effectiveness of 15% GA-coating by retaining the quality of strawberry fruits. The results show that 15% of GA-coating can be an effective strategy for enhancing the quality of strawberry fruits during cold storage without any negative effect. Practical applications The edible coating has demonstrated to be a promising food preservation method and is progressively used for the commercial processing of many fruits and vegetables. However, gum arabic has not been used for preserving the quality of highly perishable fruit such as strawberries. The result suggests that gum arabic coatings can be a valuable biochemical means of preserving strawberries during refrigerated storage and could be used as an alternative to the synthetic formulas of fruit and vegetable packaging. Thus, gum arabic coating could provide horticultural and food processors a useful way to improve the quality, prolong shelf life, and marketing strategy.

Population-Wide Survey of Salmonella enterica Response to High-Pressure Processing Reveals a Diversity of Responses and Tolerance Mechanisms.

High-pressure processing is a nonthermal method of food preservation that uses pressure to inactivate microorganisms. To ensure the effective validation of process parameters, it is important that the design of challenge protocols consider the potential for resistance in a particular species. Herein, the responses of 99 diverse Salmonella enterica strains to high pressure are reported. Members of this population belonged to 24 serovars and were isolated from various Canadian sources over a period of 26 years. When cells were exposed to 600 MPa for 3 min, the average reduction in cell numbers for this population was 5.6 log10 CFU/ml, with a range of 0.9 log10 CFU/ml to 6 log10 CFU/ml. Eleven strains, from 5 serovars, with variable levels of pressure resistance were selected for further study. The membrane characteristics (propidium iodide uptake during and after pressure treatment, sensitivity to membrane-active agents, and membrane fatty acid composition) and responses to stressors (heat, nutrient deprivation, desiccation, and acid) for this panel suggested potential roles for the cell membrane and the RpoS regulon in mediating pressure resistance in S. enterica The data indicate heterogeneous and multifactorial responses to high pressure that cannot be predicted for individual S. enterica strains.IMPORTANCE The responses of foodborne pathogens to increasingly popular minimal food decontamination methods are not understood and therefore are difficult to predict. This report shows that the responses of Salmonella enterica strains to high-pressure processing are diverse. The magnitude of inactivation does not depend on how closely related the strains are or where they were isolated. Moreover, strains that are resistant to high pressure do not behave similarly to other stresses, suggesting that more than one mechanism might be responsible for resistance to high pressure and the mechanisms used may vary from one strain to another.

Implications of the use of irradiation in the processing of animal origin foods: Review

Food irradiation has been used since the early twentieth century. It has become a safe method of animal food preservation, mainly by keeping their sensory and nutritional characteristics intact, reducing economic losses and increasing products durability. The technique can effectively eliminate or reduce foodborne microorganisms, parasites and pests without significant impact and change in composition, ensuring food safety and nutritional quality. Irradiation is currently used in meat and chicken giblets, beef, dairy products and other animal products. There is a growing consumer demand for nutritious and safe food worldwide. At the same time, contamination by microorganisms, especially of animal origin, remains a major public health problem, causing a significant increase in foodborne diseases, and thus affecting the productivity of human populations. The energy involved in irradiation is not powerful enough to affect the nucleus of the atoms within the food and, since the food does not come into contact with the radioactive source, it does not become radioactive. The process involves exposing the food, either packaged or in bulk, to carefully controlled amounts of ionizing radiation for a specific time to destroy pathogenic microorganisms. The limitation of this process concerns consumer acceptance, because they associate irradiation with radioactivity. Therefore, the present study aimed to clarify the practical benefits of food irradiation associated to a food preservation system, through a systematic literature review.

Pulsed Light Inactivation of Mushroom Polyphenol Oxidase: a Fluorometric and Spectrophotometric Study

Polyphenol oxidase (PPO) is one of the most important food enzymes; it is responsible for the browning of many foods. Pulsed light (PL) is a non-thermal method of food preservation that is able to inactivate PPO. The aim of this work was to gain insight into the mechanism of PPO inactivation by PL. To this, the kinetics of PPO inactivation by PL was measured, together with associated changes in tryptophan fluorescence, KI fluorescence quenching, and turbidity; and results were analyzed by parameter A and phase diagram methods. Enzyme inactivation followed the Weibull model. Tryptophan fluorescence decreased during PL treatment, as well as the parameter A, while Stern-Volmer constants increased and turbidity was constant. The phase diagram showed only two populated states. There was a high correlation between the loss of activity and parameter A. Results indicate that under the experimental conditions, the inactivation of PPO by PL is an all-or-none process where the enzyme progressively unfolds with no evidence of aggregation.

Evaluation of currently employed food preservation conditions to tackle biofilm forming food pathogens

AbstractControlling biofilm forming, pathogenic bacteria is an emerging challenge in the food industry, and the present study aims to test the efficacy of existing food preservation methods against these bacteria. We isolated 10 different biofilm forming pathogenic bacteria viz. Klebsiella quasipneumoniae, Bacillus cereus, Bacillus amyloliquefaciens, Bacillus anthracis, and Myroides odoratimimus from spoiled milk, biscuits, and cakes. K. quasipneumonia and B. amyloliquifaciens formed strong biofilm (OD550 &gt; 0.85), whereas B. cereus, B. anthracis, and M. odoratimimus made moderate biofilm (OD5505 &gt; 0.6) in 72 hr. The isolates, B. amyloliquifaciencs, B. anthracis, and M. odoratimimus were found positive for protease activity. The isolates showed significant tolerance to preservation conditions: pH (4–10), salt (up to 5%), temperature (up to 50°C) and sodium benzoate (up to 0.1%). The isolates also exhibited high antibiotic resistance, maximum by M. odoratimimus (MIC ≤ 256 µg/ml) against chloramphenicol which can have serious implications especially in tackling food borne illness caused by the biofilm forming food pathogens.Practical applicationsThe present study discloses the presence of biofilm forming pathogenic bacterial strains in common food stuff and their tolerance of preservation conditions and resistance to antibiotics. The occurrence of pathogens tolerant to common preservation conditions and their resistance to antibiotic should be addressed very cautiously. The significant findings of this study warrant the need for more stringent preservation methods to control food pathogens, especially the biofilm forming type. Moreover, findings of the present study will help to design novel preservation techniques such as incorporating antibiofilm coatings in food processing units and packaging materials, which will ensure food safety and public health.

The Nature and Pace of Change in American Indian Cultures: Pennsylvania, 4000 to 3000 BP

The Nature and Pace of Change in American Indian Cultures: Pennsylvania, 4000 to 3000 BP

Review on methods for preservation and natural preservatives for extending the food longevity

&lt;p&gt;Chemical, enzymatic or microbial activities from the surrounding environment and the food itself can cause spoilage to food products. In the meantime, the recent surge in world population, calls forfood products to be stored and delivered from one place to another place. During delivery, food products will start to deteriorate, losetheir appearance and decrease in nutritional values. Thus, the presence of food preservation methods such as heating, pickling, edible coating, drying, freezing and high-pressure processing can solve this problem by extending the food products‟ shelf life, stabilize their quality, maintaining their appearance and their taste. There are two categories of food preservations, the modern technology preservation method and the conventional preservation method. In the meantime, conventional food preservations usually use natural food preservatives. Meanwhile, the use of the synthetic preservative such as sulphites, benzoates, sorbates etc. for food preservation can cause certain health problems. In this light, replacing these synthetic preservatives with natural preservatives such as salt, vinegar, honey, etc. are much safer for human and environment. Furthermore, natural preservatives are easy to obtain since the sources are from plant, animal and microbes origin. This review paper focuses on preservation methodsand the natural preservatives that are suitable to be used for food preservation.&lt;/p&gt;&lt;p&gt;Chemical Engineering Research Bulletin 19(2017) 145-153&lt;/p&gt;

Inactivation of pathogenic bacteria in food matrices: high pressure processing, photodynamic inactivation and pressure-assisted photodynamic inactivation

Traditional food processing methods frequently depend on the application of high temperature. However, heat may cause undesirable changes in food properties and often has a negative impact on nutritional value and organoleptic characteristics. Therefore, reducing the microbial load without compromising the desirable properties of food products is still a technological challenge. High-pressure processing (HPP) can be classified as a cold pasteurization technique, since it is a non-thermal food preservation method that uses hydrostatic pressure to inactivate spoilage microorganisms. At the same time, it increases shelf life and retains the original features of food. Photodynamic inactivation (PDI) is also regarded as promising approach for the decontamination of food matrices. In this case, the inactivation of bacterial cells is achieved by the cytotoxic effects of reactive oxygens species (ROS) produced from the combined interaction of a photosensitizer molecule, light and oxygen. This short review examines some recent developments on the application of HPP and PDI with food-grade photosensitizers for the inactivation of listeriae, taken as a food pathogen model. The results of a proof-of-concept trial of the use of high-pressure as a coadjutant to increase the efficiency of photodynamic inactivation of bacterial endospores is also addressed.

Effect of combined static magnetic field and cold water shock treatment on the physicochemical properties of cucumbers

Based on the mechanism of temperature shock treatment and electromagnetic effect for food preservation, this paper developed a novel food preservation method by combining static magnetic field with low magnetic flux density and low-temperature water shock to process the fresh postharvest vegetable. Compared with the single cold-water shock treatment (CST, Tw = 2 °C, τ = 40 min), the static magnetic field and cold-water shock treatment (SMCT, B = 70 Gs, Tw = 2 °C, τ = 40 min) caused an increase of cooling-rate of cucumbers' tissues during treatment. Weight loss of SMCT was also lower than that of CST during storage. Furthermore, decay incidence and color difference of SMCT were about 40.2% and 10.6% lower than that of CST. Activities of catalase and superoxide dismutase for SMCT were higher than that of CST, which caused a reduction of malondialdehyde. Experimental results confirmed that SMCT had a positive influence on pre-cooling, preservation quality and physicochemical properties of cucumbers.

素材を活かす食品の保存法 : 伝統食品を見直す( 伝統産業に学ぶ : 新素材・バイオテクノロジーのルーツ)

素材を活かす食品の保存法 : 伝統食品を見直す( 伝統産業に学ぶ : 新素材・バイオテクノロジーのルーツ)

Antifungal Microbial Agents for Food Biopreservation-A Review.

Food spoilage is a major issue for the food industry, leading to food waste, substantial economic losses for manufacturers and consumers, and a negative impact on brand names. Among causes, fungal contamination can be encountered at various stages of the food chain (e.g., post-harvest, during processing or storage). Fungal development leads to food sensory defects varying from visual deterioration to noticeable odor, flavor, or texture changes but can also have negative health impacts via mycotoxin production by some molds. In order to avoid microbial spoilage and thus extend product shelf life, different treatments—including fungicides and chemical preservatives—are used. In parallel, public authorities encourage the food industry to limit the use of these chemical compounds and develop natural methods for food preservation. This is accompanied by a strong societal demand for ‘clean label’ food products, as consumers are looking for more natural, less severely processed and safer products. In this context, microbial agents corresponding to bioprotective cultures, fermentates, culture-free supernatant or purified molecules, exhibiting antifungal activities represent a growing interest as an alternative to chemical preservation. This review presents the main fungal spoilers encountered in food products, the antifungal microorganisms tested for food bioprotection, and their mechanisms of action. A focus is made in particular on the recent in situ studies and the constraints associated with the use of antifungal microbial agents for food biopreservation.

Lactic acid bacteria and their metabolites – potential biopreservatives in fish and seafood

There is growing demand for unprocessed or minimally processed food products without chem­ical preservatives. This tendency can also be observed in seafood. Therefore, traditional methods of preservation are being replaced by modern ones, e.g. biopreservation. Biopreservation is the use of non-pathogenic microorganisms and/or their metabolites to improve microbiological safety and extend the shelf life of foods. Lactic acid bacteria (LAB) and products of their metabolism, such as bacteriocins, organic acids, hydrogen peroxide, diacetyl and carbon dioxide can be successfully used as biopreservatives. LAB inhibit the growth of pathogenic and food-spoiling bac­teria, keep food fresh and extend its shelf life. About 20 years ago research began on the use of bacteria in non-fermented products such as fish and seafood, where sensory changes and nutrient modifications cannot occur. This article describes the latest reports on the use of these substances to preserve fish and fishery products, especially to provide protection from pathogenic bacteria Listeria monocytogenes. Moreover, the article presents methods of dosage into foods and synergistic combinations with other methods of food preservation.

Determination of a lexicon for the sensory flavor attributes of smoked food products

AbstractSmoking of food is one of the oldest methods of food preservation and still is used widely to help preserve foods such as ham, bacon, sausage, fish, and cheeses. Apart from its conservation function, the smoking process also has a considerable influence on the sensory characteristics of the products. A highly trained, skilled descriptive sensory panel identified, defined, and referenced 14 attributes related to the flavor of food products labeled as smoked or smoky. The panel evaluated sauces, meats, fish, cheeses, vegetables, and flavorings that are on the market in addition to samples that were smoked in‐house. Attributes attributed to the smoke flavor in each sample were written down and discussed. The list was narrowed to include only those attributes that were thought to be specifically related to the smoke flavor and not to the base notes of the product or other cooked/processed notes. The lexicon includes: Smoky (Overall), Ashy, Woody, Musty/Dusty, Musty/Earthy, Burnt, Acrid, Pungent, Petroleum‐Like, Creosote/Tar, Cedar, Bitter, Metallic, and Sour. Definitions of these attributes were written and references were found that anchor a 0–15 point scale. The references include market products, chemical solutions and commonly found non‐food products. This lexicon can be used to evaluate the smoke flavor on all types of food products.Practical applicationsThis research provides a list of sensory terms that can be used to describe the smoky flavor of products. The lexicon will help sensory analysts, product developers, researchers, and technologists better understand the flavor of products that have been naturally or artificially smoked to modify or improve the products.

Assessment of high pressure processed mandarin juice in the headspace by using electronic nose and chemometric analysis

High Pressure Processing (HPP) is a high efficient method for food preservation. As an innovative inspection method, electronic nose (E-nose) was applied to assess the HPP mandarin juices in the headspace. In this work, mandarin juices were processed by HPP at range of 0–500 MPa and diagnosed by E-nose. To improve the efficiency of E-nose, locality preserving projections (LPP) was introduced to extract information of E-nose data and compared with principal component analysis (PCA) and linear discriminant analysis (LDA). Three data extractions (stable value, max value and area value), three data reductions (PCA, LDA and LPP) and two classification algorithms (support vector machine and extreme learning machine) were applied to improve the diagnostic accuracy of E-nose. This study shows that the performance of E-nose can be enhanced by appropriate data extraction and data reduction and also gives a hint of E-nose inspection for HPP fruit juice. HHP is a high efficient technology for food preservation, including volatile compounds and solid contents. E-nose, which detect the components changes in sample's headspace, has been widely applied for the food inspection as an innovative detection method. According to authors' best knowledge, researches about E-nose detection for HHP products are not very common. In this study, E-nose is applied to detect the HHP-processed mandarin juices in the headspace. Besides, three data extractions, three data reductions and two classification algorithms were applied to improve the accuracy of E-nose determination in two HHP-process cases. This paper describes the possible application of E-nose to discriminate HHP-processed juices at different pressures. E-nose combined with appropriate pattern recognition could be used as a rapid and high efficient method to discriminate HHP-processed fruit juices.

Fresh, frozen, or ambient food equivalents and their impact on food waste generation in Dutch households

In Europe, it is estimated that more than 50% of total food waste – of which most is avoidable – is generated at household level. Little attention has been paid to the impact on food waste generation of consuming food products that differ in their method of food preservation. This exploratory study surveyed product-specific possible impacts of different methods of food preservation on food waste generation in Dutch households. To this end, a food waste index was calculated to enable relative comparisons of the amounts of food waste from the same type of foods with different preservation methods on an annual basis. The results show that, for the majority of frozen food equivalents, smaller amounts were wasted compared to their fresh or ambient equivalents. The waste index (WI) proposed in the current paper confirms the hypothesis that it may be possible to reduce the amount of food waste at household level by encouraging Dutch consumers to use (certain) foods more frequently in a frozen form (instead of fresh or ambient). However, before this approach can be scaled to population level, a more detailed understanding of the underlying behavioural causes with regard to food provisioning and handling and possible interactions is required.

The Effect of the Drying Method on the Quality of Dried Kiwi Slices

Abstract— Drying is known as a food preservation method which increases the food’s storage time by water reduction. Traditional drying consisted of open sun-drying, but different industrial dryers have been widely used in recent times. The new dryers consist of convective, infrared, ultrasound, freeze fluidized bed and freeze dryers. All of these dryers reduce the water content but under different mechanisms which leads to the end products with different qualities. In this study we aim to compare the difference in quality of kiwi fruit slices dried by three different dryers: 1. Convective tray dryer, 2. Microwave dryer and 3. Freeze dryer. The tray dryer experiments were conducted in two air temperatures of 60 and 80oC in the constant air velocity of 0.8 m/s. The microwave dryer operated in 3 output powers of 180, 270 and 360 W. The condenser temperature and pressure in the freeze dryer reduced to -50oC and 0.1 mbar, respectively. The operating conditions and time were regulated so that the moisture content of all dried samples reduced to nearly 10% in the wet basis. The three parameters of color change, ascorbic acid and antioxidant reduction were selected as the measuring criteria for the comparison of the product qualities. The experiments show that the freeze drying caused the minimum color change while the microwave drying in the maximum power of 360W caused the maximum amount of color change. The concentration of ascorbic acid was measured in the fresh fruits and dried samples by standard methods. The measurements proved that the ascorbic acid content of the freeze dried samples was 80% of the fresh fruits. The ascorbic acid content of other samples was much lower. The antioxidant activity of the dried samples and the fresh fruits was also measured by standard methods and the experimental data also showed that the freeze drying causes the minimum reduction in the antioxidant activity.

Development of antimicrobial active film containing CINnamaldehyde and its application to snakehead (Ophiocephalus argus) fish

AbstractActive packaging containing plant essential oils as a food preservation method is attracting more and more attention. Bioactive films based on ethylene vinyl alcohol copolymer (EVOH) incorporating with and without cinnamaldehyde (CIN）were prepared and characterized in this study. Physical and mechanical properties including tensile strength, elongation at break, water vapor permeability (WVP), oxygen permeability (OP), thermogravimetric analysis (TGA), and SEM image were investigated. Then active properties including release of bioactive element, antioxidant and antibacterial ability of the film sample were also conducted. Finally, the preservative effects of active films on snakehead dices stored at 4 ± 1 °C were performed by analyzing changes in pH value, water loss rate (WLR), total bacterial counts (TBC) and total volatile basic nitrogen (TVB‐N). The results showed that film A with CIN possessed higher tensile strength and lower OP compared to those of EVOH film. Moreover, the film with active element had significant antioxidant and antibacterial ability. The radical scavenging rate of the active film reached as high as 39.01%. On day 10, the TBC of fish dices in EVOH film reached 6.07 log CFU/g and the TVB‐N was 16.83 mgN/100 g, while it took 14 days for fish dices packed with film A to reach similar levels. Therefore, active packaging may prolong shelf life of aquatic food and have significance for food preservation.Practical applicationsPackaging is an essential part of food preservation. Active packaging containing antimicrobial/antioxidant compounds should extend shelf life of the products. Ethylene vinyl alcohol copolymer (EVOH) is well known packing material for its excellent oxygen barrier property. Cinnamaldehyde (CIN) is extracted from Cinnamomum cassia Presl bark and exhibits antimicrobial activity against a wide range of microorganisms. The addition of CIN into EVOH not only enhances physical and mechanical properties of the film, but also shows significant antioxidant and antibacterial ability, which can prolong the shelf life of the products. The preservative effects of the active film on fresh snakehead fish presented in this study are valuable information for practical application of active packaging to aquatic products preservation in particular, and food in general.