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UV-C light is a non-thermal technology with potential application in food industries. The objective was to assess UV-C radiation effect (13.44 W/m2) on microbiological decontamination and some quality characteristics of Cantaloupe melon juice, during refrigerated storage. Juice was inoculated with Listeria innocua (non-pathogenic surrogate of L. monocytogenes) and Alicyclobacillus acidoterrestris spores (spoilage indicators) used as indicators of the UV-C treatment efficacy. Total mesophylls and yeasts and molds were also enumerated. Results demonstrated that 5 min of exposure allowed 3.7 ± 0.3 log10 cycles reduction of L. innocua, while for A. acidoterrestris, 20 min were required to decrease 4.7 ± 0.1 log10 cycles. At the end of refrigerated storage for 13 days, UV-C treated juices retained color, total phenolics content and antioxidant activity, and yeast and molds did not grow. Since UV-C process was effective on microbial inactivation and allowed juice quality maintenance, it can be considered as a promising alternative to thermal pasteurization.

Background Carob (Ceratonia siliqua L.) is an evergreen tree that belongs to the Leguminosae family and is typical of the Mediterranean basin. It is well known for its valuable locust bean gum obtained from carob seeds. However, the food industry can obtain different carob products from carob fruit after processing. Carob products are good sources of dietary fibre, sugars, and a range of bioactive compounds such as polyphenols and D-pinitol. Scope and approach Bioactive compounds present in carob fruit and its derived products help control many health problems such as diabetes, heart diseases, and gastrointestinal disorders due to their anti-hyperglycaemic, antioxidant, and anti-inflammatory activities. So, carob products have a great potential to be used as a functional food ingredient. Key findings and conclusions This article focuses on carob characteristics and processing, chemical composition, health benefits, and applications in food formulations to explore the potential of carob in developing a wide variety of health-beneficial food products.

This work evaluated the effect of the air-drying temperature and vacuum packaging on quality and nutritional compounds of dehydrated galega kale, previously steam blanched, during 5 months of storage. When compared with the vacuum packaged kale, the packaging without vacuum yielded improved nutritional features, in general. This approach combined with a drying temperature of 40°C resulted in retention percentages of 62, 38, 92, and 48% for vitamin C, total phenolic content, total antioxidant capacity, and chlorophylls, respectively. The acceptance of the dried product by the consumer was assessed through a focus group. The participants classified the product as a practical and convenient alternative to cook healthier dishes. The appearance of dried galega kale was described as being fragile and being with nice smell, natural colour, and flavour similar to the fresh product. In conclusion, the herein presented product was addressed as an innovation with multiple possible applications in several recipes.

The aim of this study was to develop fruit powders (apple, banana and strawberry) enriched with a probiotic strain (Lactobacillus plantarum 299v). Two methodologies were proposed: (i) drying of the fruit with probiotic culture incorporated (by convection) or (ii) drying of fruit (by convection) and addition of spray-dried probiotic culture. In the first methodology, processing caused a notable reduction in probiotic viable counts in apple, but this reduction was lower during drying of banana and strawberry. A large reduction in viable cells was also recorded during storage. In the second methodology, the survival of L. plantarum 299v was considerably higher during spray-drying, and fruit powders with a microbial content suitable for a probiotic food (108-109 cfu g-1) were obtained. The fruit powders incorporating L. plantarum 299v can be stored at 4 °C or at room temperature, for at least 3 months. This preliminary study demonstrated that fruit powders are good carriers of probiotic cultures, but the techniques used to produce them should be carefully considered. Methodologies used to obtain a fruit powder with Lactobacillus plantarum: (A) drying of the fruit with probiotic culture incorporated (by convection) and (b) drying of fruit (by convection) and addition of spray-dried probiotic culture.

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

Although it is known that fruit products are rich sources of natural bioactive compounds, information on the nutritional value of their waste parts is scarce. The objective was to characterize the edible (juice and pulp) and waste (peel and seeds) parts of Cantaloupe melon (Cucumis melon L. var. reticulatus) in terms of some physicochemical characteristics, bioactive compounds and total antioxidant activity. Juice, pulp, peel and seeds represent 42, 23, 25 and 7% of total weight, respectively. Juice and pulp presented identical profiles in terms of physicochemical characteristics, bioactive compounds and antioxidant activity. They contributed to the majority of the overall content of carotenoids (80%) and vitamin C (84%) in Cantaloupe. Peel and seeds had the highest concentrations of potassium, being seeds the richest portion (7.08 ± 0.16 mg/g). Seeds had also the significantly highest total phenolics concentration (229.13 ± 20.92 µg/g), antioxidant activity (653.67 ± 169.20 µg/g), and soluble solids content (11.79 ± 0.90 °Brix). Peel stood out by the presence of chlorophylls. Since waste parts of Cantaloupe melon represent around 32% of total weight, their valorization is a challenge and strategies to improve ways of re-using them should be developed.

The objective of this work was to evaluate the drying characteristics and the effect of drying temperature on the quality characteristics of Galega kale without any pretreatment. Drying times of 330, 162, 78 and 51 min provided minimal moisture contents, using temperatures of 35, 50, 70 and 85C, respectively. The L* and a* values diminished and b* increased, resulting in increasing values of chroma, total color difference and browning index, as well as decreasing values of the hue angle. A pronounced effect on the retention of total phenolic compounds and vitamin C losses ranging from 4.8 ± 9.7 to 55.5 ± 7.4% were observed. Regarding antioxidant capacity, losses from 51.7 ± 7.5 to 69.6 ± 3.7% were obtained. Chlorophyll a content decreased with increasing drying temperatures, with losses between 8.9 ± 6.7 and 35 ± 5.6%, while degradation of chlorophyll b was negligible. In conclusion, the air drying of Galega kale without any pretreatment resulted in considerable deterioration of its quality characteristics and nutritional value. Practical Applications Drying processes are often applied to preserve and increase the shelf life of vegetables. These products contain an extensive collection of phytochemicals known to provide health benefits. However, these compounds generally undergo significant degradation during drying because of their sensitivity to heat, light, oxygen, as well as to leaching phenomena. Thus, increased attention has been given to the concerns regarding the quality degradation of vegetables during drying. Galega kale was the selected vegetable as information concerning the influence of drying on the quality parameters of this vegetable is scarce. Additionally, this vegetable is known to present several healthy nutrients, but after harvest it is easily perishable. Therefore, drying could be a valuable strategy to preserve and increase the shelf life of this product. Thus, this work evaluates the impact of the drying temperature on the quality properties of Galega kale without the employment of any pretreatment.

Many minimally processed foods depend on a combination of inhibitory factors to reduce the hazard of foodborne illness. Therefore, inactivation of Listeria innocua was studied according to a 24 factorial experiment designed to draw conclusions about temperature (52.5 °C and 65.0 °C), pH (4.5 and 7.5), water activity (aw=0.95 and 0.99) and solute type (NaCl and glycerol) effects. Three different recovery media were used to assess injured cells. Survival data were fitted with a Gompertz-based model and kinetic parameters (shoulder, maximum inactivation rate – kmax, and tail) were estimated. Results showed that shoulder was affected by temperature, pH and combined effects; kmax was influenced by all factors and their combinations; and tail was affected by aw, temperature and aw/pH combination. Results demonstrated the potential occurrence of microbial cross-protection survival techniques between the various stresses, e.g. heat and osmolarity. Indeed, this work clearly established that, to avoid hazards, Listeria inactivation must be evaluated with a maximum of environmental factors that undergo alterations. Only thus, appropriate food preservation treatments can be developed and consequently, the safety of food products can be assured.

Byssochlamys fulva is an ascospore producer fungus known to be heat resistant and commonly found in fruit juices. This work aims at studying the influence of soluble solid content and storage temperature on the growth of B. fulva in apple juices. Agar-added apple juices, adjusted to different levels of soluble solids (12, 20, 25, 35, 45, 55, 70 degrees Bx) were artificially inoculated with B. fulva spores and incubated at different temperatures (10, 15, 20, 25, 30 degrees C). Microorganisms' growth was assessed every day for a total of 3 months. A Gompertz-based model was used in experimental data fit for each soluble solid and temperature condition applied. Kinetic parameters were estimated by nonlinear regression procedures. The soluble solids and temperature effects were thereafter included in the primary Gompertz-based model. The predictive ability of this expression in terms of B. fulva growth was successfully proven for the range of conditions tested.

This study evaluated the effect of water heat treatment (WHT, immersion in a water bath at 40C – 30 min) application in alternative to the conventional decontamination treatment of chlorinated water (150 ppm at 5C, pH 6.5 during 2 min) on tomato (cv. Zinac) at two maturity stages (turning and pink). Physiochemical attributes, enzymatic activities and microbial load were evaluated after treatments and during 14 days of storage at 10C. The WHT applied was very effective on microbial reduction and delayed physiochemical changes of tomato, namely firmness loss and red color development during storage period, especially at turning maturity stage. Based on the firmness parameter, shelf-life of control and WHT samples were determined. Our results provide strong evidence that postharvest WHT (40C – 30 min) for tomato fruits at turning maturity stage guarantees the overall quality at 10C twice as long of fruits washed with chlorinated water. Practical Applications Tomato is a popular fruit due to its high nutritional value and culinary versatility. However, tomato shelf-life is limited, especially if commercialized in an advanced maturity stage. Water heat treatment (WHT) is a promised postharvest processing to extend quality of fresh crop. WHT (40C – 30 min) applied to whole tomato (cv. “Zinac”) was found to be effective for microbial reduction and guarantees its overall quality at 10C for a double period, especially in early maturity stages, compared with conventional treatments, without presenting the chemical risks associated to by-products of chlorinated water.

The effects of storage at different temperatures (2, 5, 10, 15, and 20 degrees C) conditions on whole tomato (Solanum lycopersicum, cv. 'Zinac', fruits harvested at mature-green stage) quality parameters, such as colour, chilling injury, firmness, weight loss and total phenolic content, were investigated during a month period. Storage at all temperatures had significant impact on the quality parameters analysed. Significant alterations in tomato green colour, firmness and weight loss were observed. The results also revealed a slight increase in the total phenolic content, and that refrigeration storage at 2 and 5 degrees C induced chilling injuries. A fractional conversion model fitted well the experimental data on colour parameters (a. and degrees h value), firmness and weight loss. The storage temperature effect was successfully described by the Arrhenius law. These results represent a good predictive tool for tomato quality estimation along the food chain.

Submitted by Ana Costa (apcosta@porto.ucp.pt) on 2016-11-21T16:15:13Z No. of bitstreams: 1 Antilisterial active compound from lactic acid bacteria present on fresh iceberg lettuce.pdf: 306122 bytes, checksum: ae063e0347bc5e1d07a46d79e4771f0a (MD5) Made available in DSpace on 2017-10-13T20:08:36Z (GMT). No. of bitstreams: 1 Antilisterial active compound from lactic acid bacteria present on fresh iceberg lettuce.pdf: 306122 bytes, checksum: ae063e0347bc5e1d07a46d79e4771f0a (MD5) Previous issue date: 2016 info:eu-repo/semantics/publishedVersion

The objective of this work was to evaluate the effect of six pretreatments on quality and nutritional contents of sliced Galega kale submitted to convective drying. Among all treatments, steam blanching was the most favourable, allowing improvements in retention of vitamin C, total antioxidant capacity and chlorophylls in comparison to the absence of pretreatment. Total phenolic losses were not reduced by steam blanching, but the retention was improved by combining this approach with a previous immersion in a metabisulphite solution. Moreover, steam blanching improved the colour parameters and appearance, providing a final dried product more similar to the fresh sample.

Textural changes during fruit ripening have been attributed to pectin degradation due to pectic enzymes such as pectinmethylesterase (PME, EC 3.1.1.11). PME catalyzes the de-esterification of pectin, a complex mixture of polysaccharides, namely methyl esterified polygalacturonic acid, with the release of hydrogen and methanol, producing shorter chains causing drastic losses in firmness. Thus, control of PME activity in fruits aiming at texture maintenance and/or improvement is extremely important to the food industry. However, PME activity and properties are dependent on product, environmental and physico-chemical conditions, such as pH and temperature. Therefore, the aim of the present work was to optimize the pectinmethylesterase (PME) enzyme assay from tomato (Solanum lycopersicum 'Zinac') fruits, and determine its kinetics behavior and thermal stability. The highest PME activity was found with a 1.0 M of NaCl extraction solution, with 0.5% citrus pectin, and revealed optima of temperature at 60°C and pH of 8.8. The low kM value (0.011%) for tomato PME describes the high affinity between enzyme and substrate (citrus pectin), whereas the obtained Vmax value (0.712 U mg-1) relates to the enzyme quantity present in the reaction. The study of PME thermal stability showed two distinct behaviors: an increase of activity from 40 to 50°C and a decrease from 55 to 80°C. At 50°C/10 min an increase in activity up to 17% of activity was observed. At 60°C, about 50% of the activity still remained after heating for 25 min, and PME was completely inactivated at 80°C after 10 min. Data obtained in the temperature range of 55 to 80°C were also satisfactorily described by an Arrhenius first-order kinetic model. These results provide useful information about the different factors that affect tomato PME activity and may be used as a tool for firmness control during postharvest handling and fruit processing.

The effectiveness of ozone in aqueous solution treatment on microbial inactivation was studied for three combinations microorganism/food: Listeria innocua/red bell peppers (artificially inoculated), total mesophiles/strawberries, and total coliforms/watercress, with two concentrations (0.3 and 2.0 ppm). Blanching treatments (50-60 degrees C) were also individually applied and in combination with ozone, for studying possible synergistic effects. In relation to ozone treatments, the highest microbial reductions were obtained for the highest concentration with the highest treatment time (3 min). Under those conditions. L. innocua/peppers, total mesophiles/strawberries and total coliforms/watercress were reduced respectively 2.8 +/- 0.5, 2.3 +/- 0.4 and 1.7 +/- 0.4 log-cycles. However, a substantial portion of the microbial populations were reduced by water washing alone, and the presence of ozone generally added an additional reduction of 0.5-1.0 log-cycles. If ozone at the highest concentration is used, the treatment impacts on L. innocua/peppers and total mesophiles/strawberries load reductions were equivalent to a blanching at 50 degrees C (for the same treatment times). Combining blanching and ozone did not generate synergistic effects, and in some situations microbial reductions were lower than the ones observed when treatments were applied independently.

Ethylene oxide is currently a dominant agent in medical device sterilization. This work intends to study the main effects and interactions of temperature, ethylene oxide concentration, and relative humidity on commercial spore strips of Bacillus subtilis, var. niger (ATCC 9372) inactivation, the most common microorganism used in controlling the efficacy of the process. Experiments were carried out using a full factorial experimental design at two levels (2(3) factorial design). Limit target exposure conditions for ethylene oxide concentration, temperature, and relative humidity were 250-1,000 mg EO/l, 40-60A degrees C, and 50-90%, respectively. Adopting a different approach from the first-order kinetics, a Gompertz model was successfully applied in data fitting of the inactivation curves. Bacillus subtilis kinetic behavior presented a sigmoidal inactivation with an initial shoulder (lambda), followed by a maximum inactivation rate (k(max)), these being model parameters. It was concluded that temperature and ethylene oxide concentration were the most significant factors and consequently, additional experiments were carried out aiming at describing the parameters' dependence on these process factors. Mathematical relations describing such dependences were successfully developed and included in the Gompertz kinetic model. The predictive ability of this integrated model was assessed, and its adequacy in predicting B. subtilis inactivation was proven.

The objective of this work was to study the effect of three linear temperature profiles (heating rates of 1.5, 1.8 and 2.6 °C/min, from 20 to 65 °C) on Listeria innocua inactivation in liquid medium. The inactivation was also analyzed in artificially contaminated parsley (heating rate of 1.8 °C/min) and throughout a frying process, using a pre-cooked frozen food as case study. Inactivation showed a sigmoidal behaviour and all data was fitted with a Gompertz-inspired model. Results demonstrated that, in liquid media, Listeria inactivation is influenced by the temperature profile used. As heating rate increases, the shoulder decreases and the tail effect disappears. If Listeria was in parsley, its heat resistance increased (for identical experimental conditions in broth). Besides model adequacy was proven in all studied situations, the heating rate affected parameters’ precision.

Listeria innocua inactivation was studied within the temperature range 52.5-65.0 °C, comparing two different strains (10528 and 2030c) and two growth phases (exponential and stationary). Survival curves may present a sigmoidal behaviour, with an initial shoulder (L), followed by a maximum inactivation rate (kmax) period and a final tailing tendency. A Gompertz-inspired model was used to fit experimental data, and kinetic parameters (L, kmax and tail) were estimated by non-linear regression analysis. The influence of temperature, growth phase and strain on kinetic parameters was studied using a 23 factorial experimental design. Results showed that temperature and growth phase were the most significant variables affecting the kinetic parameters. Listeria thermal inactivation varied from a log-linear tendency till a pronounced sigmoidal behaviour, depending on the studied factors.

BACKGROUND: Egg yolk cream is confectioned with egg yolk, sugar and water. Pasteurized liquid eggs may be used in order to increase product safety, although these samples may differ from the classic ones produced with raw eggs. The objective was to evaluate and compare the stability (physicochemical characteristics, such as texture assessment, pH and water activity, and microbiological assessment) of a classic formulation and an alternative one produced with pasteurized eggs, during storage at 6, 26, 30 and 37 °C. RESULTS: From a microbiological point of view (mesophile and psychrotrophic activity), no differences were observed in either formulations. At 6 and 26 °C, rheological behaviour of both formulations remained approximately constant. At 30 and 37 °C, differences were only detected after 20 days of storage. Texture was better retained in samples prepared with pasteurized eggs, while the classic samples showed an increase in complex viscosity. CONCLUSION: Cream storage did not require refrigeration. In terms of texture and microbial load, results obtained at 6 and 26 °C were identical. The formulations only differed in texture when stored at 30 and 37 °C and for long periods. These conclusions may allow reduction of costs related to refrigerated distribution/storage of either classic or alternative formulations. Copyright © 2008 Society of Chemical Industry

The effect of UV-C treatments (0.32, 0.97, 2.56, 4.16 and 4.83 kJ.m(-2) at 254 nm) on the physical-chemical properties [colour, texture, total phenolic content (TPC), weight loss (WL)], and mesophylic counts of whole tomato, was evaluated during 15 days at 10 A degrees C. During storage, the Ctr samples acquired faster red colour than all UV-C samples (higher a* and lower A degrees h values). Comparing texture of Ctr and UV-C samples at 15(th) storage day, an increase of 9 and 8 % on firmness of treated samples at low UV-C intensities (0.32 and 0.97 kJ.m(-2), respectively) was observed. At the end of the storage, Ctr samples showed ca. 4 Log(10) of mesophylic load, and the samples treated at 0.97 and 4.83 kJ.m(-2) revealed the lowest microbial load (1.9 and 3.2 Log(10), respectively). These results indicate that UV-C radiation, at an appropriate dose, combined with low storage temperature (10 A degrees C) are an effective method to preserve the postharvest life of tomato, without adversely affecting quality parameters.

Frozen green beans ( Phaseolus vulgaris , L.) thawing is one of the operations that compromises significantly quality. The present research aims at studying the effects of thawing, at environmental and refrigeration temperatures, on the quality profile of a frozen green beans package. Quality losses were computationally evaluated, using a simulation system based on object-oriented technologies. Simulations show that sensory parameters, such as flavour and colour, are more sensitive to thawing at environmental temperatures, than nutritional parameters, such as vitamin C and starch contents. The study demonstrates that green beans quality retention is also influenced by packaging materials, with different degrees of thermal insulation, and environmental conditions, such as temperature and surface heat convection coefficients. Important conclusions are discussed on shelf-life limiting quality parameters during thawing and temperature abuses, as well as on thawing green vegetables to maximise their quality profile. Results emphasise that the principle of high-temperature–short-times is not directly applicable to frozen green beans thawing. Furthermore, simulations lead to the conclusion that overall quality profile is maximised by thawing under refrigeration temperatures.

Texture, vitamin C, reducing sugars, and starch quality changes of frozen green beans (Phaseolus vulgaris L.) were studied for 250 d at storage temperatures of -7, -15, and -30°C. All studied parameters suffered significant changes during frozen storage. Texture loss was described by a fractional conversion model, while ascorbic acid and starch evolution were successfully modeled with first-order reaction kinetics. Dehydro-ascorbic acid (DHAA) degraded only 8% during storage time, and thus frozen storage well preserves total vitamin C. The low estimated Arrhenius activation energies of texture, starch, and ascorbic acid losses emphasize that low temperatures do not substantially reduce degradation rates.

Cupuaçu (Theobroma grandiflorum) is an Amazonian tropical fruit with a great economic potential. Pasteurization, by a hot-filling technique, was suggested for the preservation of this fruit pulp at room temperature. The process was implemented with local communities in Brazil. The process was modeled, and a computer program was written in Turbo Pascal. The relative importance among the pasteurization process variables (initial product temperature, heating rate, holding temperature and time, container volume and shape, cooling medium type and temperature) on the microbial target and quality was investigated, by performing simulations according to a screening factorial design. Afterward, simulations of the different processing conditions were carried out. The holding temperature (TF) and time (t hold) affected pasteurization value (P), and the container volume (V) influenced largely the quality parameters. The process was optimized for retail (1 L) and industrial (100 L) size containers, by maximizing volume average quality in terms of color lightness and sensory "fresh notes" and minimizing volume average total color difference and sensory "cooked notes". Equivalent processes were designed and simulated (P 91°C = 4.6 min on Alicyclobacillus acidoterrestris spores) and final quality (color, flavor, and aroma attributes) was evaluated. Color was slightly affected by the pasteurization processes, and few differences were observed between the six equivalent treatments designed (TF between 80 and 97°C). TF ≥ 91°C minimized "cooked notes" and maximized "fresh notes" of cupuaçu pulp aroma and flavor for 1 L container. Concerning the 100 L size, the "cooked notes" development can be minimized with TF ≥ 91°C, but overall the quality was greatly degraded as a result of the long cooling times. A more efficient method to speed up the cooling phase was recommended, especially for the industrial size of containers.

Colour changes and chlorophyll degradation of frozen green beans (Phaseolus vulgaris, L., variety bencanta) were studied during 250 days of storage at 7, 15 and 30 C. Chlorophyll a and b losses and colour Hunter a and b coordinates and total colour difference (TCDH) changes were successfully described by first order and reversible first order models, respectively. The temperature effect was described by the Arrhenius law. Disagreement between the colour co-ordinates and chlorophyll content was obtained. Therefore, chlorophyll content is not a good colour index of frozen green beans. The results emphasise that colour is a more important parameter to assess frozen green beans visual quality. # 2002 Elsevier Science Ltd and IIR. All rights reserved.

The microbiological safety of fresh produce is a significant concern of consumers and industry. After applying at an inoculated level (6–7 log CFU/mL) of Listeria monocytogenes on Iceberg lettuce, the antilisterial properties of balsamic vinegar from Modena, white wine vinegar and acetic acid solutions were investigated. Different proportions of the vinegars, acetic acid (58.7 g/L), and deionized water were evaluated to determine the role of those solutions at the stage of washing Iceberg lettuce to remove L. monocytogenes . The maximum observed log reduction of L. monocytogenes was 2.15 ± 0.04 for balsamic vinegar (50% (v/v)), 1.18 ± 0.06 for white wine vinegar ((50% (v/v)) and 1.13 ± 0.06 for acetic acid ((50% (v/v)). Washing with water only reduces 0.05 ± 0.04 log CFU/mL of L. monocytogenes numbers. Listeria reductions observed for balsamic vinegar are similar or higher than those of chlorine-based sanitizers evaluated in other studies with lettuce. In the case of balsamic vinegar solutions, Listeria inhibition followed a linear reduction according to the model: Log ( N / N 0 ) = −4.09 × balsamic vinegar proportion % (v/v) − 0.13; R ² = 0.95. Balsamic vinegar washings may be a promising method for reducing other foodborne pathogens present in produce or other foods, at home and retail environments.

Changes in 'fresh' and 'cooked-notes' during thermal treatment of cupuacu (Theobroma grandiflorum) pulp were evaluated and modelled. Isothermal experiments in the temperature range of 70-98 °C were carried out and a non-linear regression was performed to all data to estimate kinetic parameters. 'Fresh' and 'cooked-notes' change followed simple first-order (Ea = 78-82 kJ·mol-1 , z = 30-31 °C) and reversible first order (Ea = 80-85 kJ·mol-1 ) kinetics, respectively. Although 'cooked-notes' were linearly correlated with 'fresh-notes' (R2 = 0.99), the former was a better indicator for quality degradation. These results are useful to design pasteurisation processes while minimising sensory changes. © 2000 Society of Chemical Industry.

Colour changes in thermally treated cupuacu (Theobroma grandiflorum) fruit puree were modelled mathematically. Isothermal experiments in the temperature range of 80-115 °C were performed and colour was measured by a tristimulus colorimeter. At each temperature total colour difference (TCD * ) increased and normalized L * decreased with processing time, both following a power law model. The power of the model was temperature-dependent and described by the Arrhenius law. To estimate the model constants, a one-step non-linear regression was performed on all data. Activation energies of 31 and 36 kJ/mol were determined for TCD * and normalized L * , respectively. These results should prove useful in the design of pasteurization processes which minimize colour changes in cupuacu puree.

Water heat treatments (WHT) are applied to fresh fruits for disinfection purposes as well as to promote changes to the biochemical pathways involved in the ripening process, resulting in remarkable beneficial effects on postharvest quality maintenance and storage life extension. The objective of this study was to evaluate the overall effects of WHT on tomato (Solanum lycopersicum 'Zinac') quality and to determine an optimal WHT condition to extend its shelf-life. Fruits were immersed in hot water at different temperatures (from 40 to 60°C) and during different periods of time (2 to 60 min). WHT effects on fruit colour CIELab parameters (a* and °h), firmness (N), peroxidase (POD) and pectinmethylesterase (PME) enzyme activity, total phenolic content (TPC) and microbial load (mesophylic and yeasts & moulds counts (Y&M)) were evaluated. After WHT no observable color changes were denoted in all heat treated samples. At lower WHT, 40-50°C, maintenance in firmness was obtained when compared to untreated samples. Significant reductions on tomato firmness were observed in treatments with temperatures higher than 55°C. Both evaluated enzymatic activities were affected by the heat treatments. Regarding POD enzyme, an increase in its activity was found with intensive WHT, while PME activity decreased at all tested conditions with two exceptions (45 and 60°C). In fruits treated at 40°C/30 min the highest increase in TPC was found when compared to the control sample (ca. 27%). WHT at 50°C/2 min or 40°C/30 min promoted a reduction in mesophylic and Y&M load to undetectable levels, showing the effectiveness of these treatments to control microbial development in tomato fruits. Therefore, these treatments present an alternative postharvest process for tomato storage with beneficial effects to fruit quality as well as extension of shelf life.

The impact of sodium hypochlorite and hydrogen peroxide (H 2O 2 at 1 and 5%) solutions on Listeria innocua in red bell peppers, total mesophiles in strawberries and total coliforms in watercress was studied. Quality attributes such as colour, firmness and pH were studied for all products; total anthocyanins content was determined for strawberries. Sensorial analyses were also carried out for all products. Results showed that H 2O 2 (5%) provided the highest reductions of microbial loads. Besides H 2O 2 (1%) had a lower impact, it was more effective than water-washings. Sodium hypochlorite solutions lead to microbial reductions comparable to water risings. In terms of quality, H 2O 2 (5%) was the solution with higher negative impact on products' colour. For strawberries, such colour alterations were also detected by sensorial analyses. The anthocyanins content decreased significantly. Overall it was found that H 2O 2 (1%) was a good sanitizer solution, since microbial reduction was attained while quality factors did not suffer considerable alterations.

Ozone is a strong sanitizer that can be applied as a convenient washing-treatment to foods. The main objective was to study the ozone impact on Listeria innocua in red bell peppers, total mesophiles in strawberries and total coliforms in watercress. Modelling microbial load reduction throughout treatment time and due to ozone effect were also targets. The microbiological reductions observed for ozonated samples were higher than the ones obtained for water dipping. However, total coliforms/watercress were less sensitive to both deionized-water and ozonated-water washings. A Weibull-based model was adequate in describing microbiological reductions and may contribute to design more effective sanitizing processes.

The kinetics of peroxidase thermal inactivation, total phenolic content degradation, and colour (CIE L∗a∗b∗) and texture changes were studied in a temperature range of 70–90 °C for carrots (Daucus carota L.). Peroxidase inactivation, total phenolic content degradation and the lightness colour (L∗ parameter) change were successfully described by a first-order reaction model. The redness and yellowness colour (a∗ and b∗ parameters, respectively) and texture (firmness and energy parameters) changes presented a fractional conversion kinetic model behavior. The temperature effect was well described by the Arrhenius law. All the blanching conditions recommended to reduce peroxidase inactivation to an acceptable level (90% loss of its original activity) ensured good quality retention. However, to obtain a high quality carrot product a balance must be made between colour and total phenolic content losses. Therefore, blanching at 80 °C for 6 min is suggested as a compromise condition to maximize quality. The overall study indicated that colour is a critical parameter to optimize carrot hot water blanching condition.

Watercress is an herb traditionally consumed fresh. If frozen, would be readily available to consumers. However, pathogenics resistant to frozen storage are a safety concern in this new product. in this study watercress was artificially contaminated with Pseudomonas aeruginosa ATCC 27853 and Enterococcus faecalis ATCC 29212. Their survival was evaluated after blanching, frozen storage and temperature fluctuations of the frozen product. The blanching caused a reduction of about 2 log cfu per gram of product of total viable count (TVC) and about 1.7 and 1.3 log cfu per gram of product of P. aeruginosa and E. faecalis, respectively. P. aeruginosa seemed to be more sensitive to temperature abuses than E. faecalis. After 3 months, TVC was still observed with a reduction of about 3 log cfu per gram of product. At the end of the study, exposure to freeze-thaw cycles resulted in death or injury of the microorganisms. These findings on the behaviour of two microorganisms of concern in frozen watercress will help improving the safety and cold chain settings for this product. (C) 2008 Elsevier Ltd and IIR. All rights reserved.

The effects of water blanching treatment on peroxidase inactivation, total phenolic content, color parameters [-a*/b* and hue (h degrees*)], texture (maximum shear force), and sensory attributes (color and texture, evaluated by a trained panel) of broccoli (Brassica oleracea L. ssp. Italica) were studied at five temperatures (70, 75, 80, 85, and 90 degrees C). Experimental results showed that all studied broccoli quality parameters suffered significative changes due to blanching treatments. The vegetal total phenolic content showed a marked decline. Degradation on objective color and texture measurements and alterations in sensorial attributes were detected. Correlations between sensory and instrumental measurements have been found. Under the conditions 70 degrees C and 6.5 min or 90 degrees C and 0.4 min, 90% of the initial peroxidase activity was reduced. At these conditions, no significant alterations were detected by panelists, and a small amount of phenolic content was lost (ca. 16 and 10%, respectively). The peroxidase inactivation and phenolic content degradation were found to follow first-order reaction models. The zero-order reaction model showed a good fit to the broccoli color (-a*/b* and h degrees*), texture, and sensory parameters changes. The temperature effect was well-described by the Arrhenius law.

The effects of blanching treatment on peroxidase inactivation, colour and texture of pumpkin (Cucurbita maxima L.) were studied in the temperature range of 75-95 °C. Peroxidase inactivation followed a first-order Arrhenius model, where the activation energy and rate of the reaction at a reference temperature of 85 °C were 86.20 ± 5.57 kJ mol-1 and 0.27 ± 0.01 min-1, respectively. During blanching, pumpkin became darker and softer with processing time. The degradation of colour (evaluated throughout CIE L*a*b* colour system, with chroma index and total colour difference) and texture parameters (firmness and energy) showed a fractional conversion model kinetics, being the temperature effect on kinetic parameters well described by the Arrhenius law. The results of this work are a good tool to further optimise pumpkin blanching conditions.

Listeria innocua was subjected to thermal inactivation and the extent of heat-injured cells was quantified. Cultures were heated in liquid medium for different times, using temperatures in the range of 52.5 to 65.0 °C, and plated on Tryptic Soy Agar with 0.6% yeast extract (TSAYE) used as non-selective medium and on TSAYE plus 5% NaCl (TSAYE + NaCl) and Palcam agar with selective supplement (Palcam agar) as selective media. The difference observed in counts in non-selective and in selective media gave an indication of cell injury during the heat treatment. D- and z- values were calculated for all conditions considered. For each temperature, D-values obtained using non-selective recovery procedures were higher than the ones obtained using the two selective media. When comparing the selective media, it can be concluded that Palcam agar allowed recovery and growth of thermally injured cells and so it was less inhibitor than TSAYE + NaCl. Another important result was the influence of temperature on the degree of cellular injury. As temperature increases, the degree of heat-injured cells also increases, and consequently concern has to be taken with the temperature and the counting medium used in food processing studies. The results of this work clearly demonstrated that selective media used for Listeria monocytogenes enumeration/detection might not be suitable for the recovery of heat-injured cells, which can dangerously underestimate the presence of this foodborne pathogen.

The effect of heat and the combined heat/ultrasound (thermosonication) treatment on the inactivation kinetics of peroxidase in watercress (Nasturtium officinale) was studied in the temperature range of 40–92.5 °C. In the heat blanching processes, the enzyme kinetics showed a first-order biphasic inactivation model. The activation energies and the rates of the reaction at a reference temperature for both the heat-labile and heat-resistant fractions were, respectively, Ea1 = 421 ± 115 kJ mol−1 and Ea2 = 352 ± 81 kJ mol−1, k 1 84 . 6 ° C = 18 ± 14 min - 1 and k 2 84 . 6 ° C = 0 . 24 ± 0 . 14 min - 1 . The initial relative specific activity for both isoenzyme fractions were also estimated, being C01 = 0.5 ± 0.08 μmol min−1 mg protein−1 and C02 = 0.5 ± 0.06 μmol min−1 mg protein−1, respectively. The application of thermosonication was studied to enable less severe thermal treatments and, therefore, improving the quality of the blanched product. In this treatment the enzyme kinetics showed a first-order model. The activation energy, the rate of reaction at a reference temperature and the initial relative specific activity were, respectively, Ea3 = 496 ± 65 kJ mol−1, k 3 87 . 5 ° C = 10 ± 2 min - 1 and C03 = 1 ± 0.05 μmol min−1 mg protein−1, proving that the enzyme became more heat labile. The present findings will help to design the blanching conditions for the production of a new and healthy frozen product, watercress (Nasturtium officinale), with minimized colour or flavour changes along its shelf life.

A Cupuaçu (Theobroma grandiflorum) nectar formulation was optimized, for European consumers, using an augmented simplex centroid mixture design. The working ranges, x1, (Sugar, 10-25%), x2(Cupuaçu, 15-30%) and x3 (Water, 60-75%), were based on a common Brazilian recipe. As responses, a sensory panel evaluated taste, acidity, sweetness, viscosity, mouthfeel and overall opinion. For each response, the best mathematical predictive model was chosen, based on Response Surface statistical analysis. An optimization was then performed, and the optimum was Cupuaçu (18.5%), Sugar (11%) and Water (70.5%). Tolerance tests were carried out and, although differences were detected (α = 5%), the level of acceptance remained above average.