scholarly journals Modeling the impact of water activity, pH, and calcium propionate on the germination of single spores of Penicillium paneum

LWT ◽  
2020 ◽  
Vol 133 ◽  
pp. 110012
Author(s):  
Juliana L.P. Santos ◽  
Rafael D. Chaves ◽  
Anderson S. Sant’Ana
Keyword(s):  
Water Activity ◽  
Calcium Propionate ◽  
The Impact ◽  
Penicillium Paneum

scholarly journals Brine Solution with Hydrocolloids Used to Enhance the Properties of Sterilized Meat

2020 ◽  
Vol 58 (2) ◽  
pp. 173-182
Author(s):  
Vinicius Jose Bolognesi ◽  
Michele Rigon Spier ◽  
Carlos Eduardo Rocha Garcia
Keyword(s):  
Water Activity ◽  
Thermal Inactivation ◽  
Soy Protein Isolate ◽  
Meat Products ◽  
Protein Isolate ◽  
Salt Mass ◽  
Mass Fractions ◽  
Retort Processing ◽  
The Impact ◽  
Control Samples

Research background. Retort processing is one of the most widely used methods of thermal inactivation that provides convenient, ready-to-eat foods. Although this technology remains widespread, it can be revamped through processing of novel ingredients such as gums. This article aims to investigate the effect of the hydrocolloids collagen, soy protein isolate, carrageenan and modified starch with different salt mass fractions on the retorted meat products. Experimental approach. Firstly, solutions of the added hydrocolloids of different salt mass fractions in order to stimulate the salting-in effect were studied. Lipid oxidation, syneresis and water activity were analysed during shelf life to find the best overall treatments. Lastly, sensory and texture analyses were then performed to assess the impact of the added hydrocolloids. Results and conclusions. Yield, cooking loss and water-holding capacity had better results when higher salt mass fractions with hydrocolloids were used. The physicochemical results distinguished collagen from the other tested hydrocolloids. Syneresis remained in similar ranges regardless of the treatment. No difference was observed in water activity either. However, sterilization, vacuum sealing and the addition of a hydrocolloid contributed to low oxidation levels in all treatments. Lastly, sensory, texture and shear force analyses confirmed that the products with collagen were harder and firmer than the control samples, which explains the preference of control samples by the panellists. Nevertheless, assessors did not perceive the presence of collagen. Novelty and scientific contribution. Physicochemical and sensory characteristics of the retorted meat can be considerably improved when brine and hydrocolloids are combined with the retort technology.

scholarly journals The Impact of (bio-)organic substances on the ice nucleation activity of the K-feldspar microcline in aqueous solutions

2021 ◽  
Author(s):  
Kristian Klumpp ◽  
Claudia Marcolli ◽  
Thomas Peter
Keyword(s):  
Amino Acids ◽  
Citric Acid ◽  
Carboxylic Acids ◽  
Water Activity ◽  
Active Sites ◽  
Ice Nucleation ◽  
Organic Substances ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
The Impact

Abstract. Potassium-feldspars (K-feldspars), such as microcline, are considered key dust minerals inciting ice nucleation in mixed phase clouds. Besides the high ice nucleation activity of microcline, recent studies also revealed a high sensi-tivity of microcline towards interaction with solutes on its surface. Here, we investigate the effect of organic and bio-organic substances on the ice nucleation activity of microcline, with the aim to better understand the underlying sur-face interactions. We performed immersion freezing experiments with microcline in solutions of three carboxylic acids, five amino acids and two polyols to represent these compound classes. By means of a differential scanning calorimeter we investigated the freezing of emulsified droplets of microcline suspended in various solutions. Depend-ing on the type of solute, different effects were observed. In the case of carboxylic acids (acetic, oxalic and citric acid), the measured heterogeneous onset temperatures, Thet, showed no significant deviation from the behavior pre-dicted by the water activity criterion, Thet(aw) = Tmelt(aw+Δaw), which relates Thet with the melting point temperature Tmelt via a constant water activity offset Δaw. While this behavior could be interpreted as a lack of interaction of the solute molecules with the surface, the carboxylic acids caused the fraction of heterogeneously frozen water, Fhet(aw), to decrease by up to 40 % with increasing solute concentrations. In combination, unaltered Thet(aw) and reduced Fhet(aw) suggest that active sites were largely deactivated by the acid molecules, but amongst those remaining active are also the best sites with the highest Thet. A deviation from this behavior is citric acid, which showed not only a de-crease in Fhet, but also a decrease in Thet of up to 4 K for water activities below 0.99, pointing to a depletion of the best active sites by interactions with the citrate ions. When neutralized solutions of the acids were used instead, the de-crease in Fhet became even more pronounced. The slope of Thet(aw) was different for each of the neutralized acid solu-tions. In the case of amino acid solutions, we found a decrease in Thet (up to 10 K), significantly below the Δaw-criterion, as well as a reduction in Fhet (up to 60 %). Finally, in case of the investigated polyols, no significant devia-tion of Thet from the Δaw-criterion was observed, and no significant deviation of Fhet in comparison to a pure water suspension was found. Furthermore, we measured the effects of aging on the ice nucleation activity in experiments with microcline suspended in solutions for up to seven days, and tested the reversibility of the interaction with the solutes after aging for 10 days. For citric acid, an ongoing irreversible degradation of the ice nucleation activity was observed, whereas the amino acids showed completely reversible effects. In summary, our experiments demonstrate a remarkable sensitivity of microcline ice nucleation activity to surface interactions with various solutes, underscoring the importance of the history of such particles from source to frozen cloud droplet in the atmosphere.

On the impact of water activity on reversal tolerant fuel cell anode performance and durability

2016 ◽  
Vol 328 ◽  
pp. 280-288 ◽  
Author(s):  
Bo Ki Hong ◽  
Pratiti Mandal ◽  
Jong-Gil Oh ◽  
Shawn Litster
Keyword(s):  
Fuel Cell ◽  
Water Activity ◽  
Cell Anode ◽  
Fuel Cell Anode ◽  
The Impact

scholarly journals THE IMPACT OF INDONESIAN TERASI IN THE BEEF CONSOMMÉ, A SENSORY ASSESSMENT

2017 ◽  
Vol 4 (1) ◽  
pp. 132
Author(s):  
Mery Tambaria Damanik Ambarita
Keyword(s):  
Water Activity ◽  
Proximate Composition ◽  
Salt Content ◽  
Sensory Assessment ◽  
Sensory Acceptability ◽  
Sensory Acceptance ◽  
Different Types ◽  
Pungent Odor ◽  
The Impact

The aim of this research was to investigate the impact of terasi, a traditional Indonesian condiment which is made from salted fermented seafood, on the sensory acceptance of beef consommé. Fifty four panelists compared the acceptance of beef consommé containing rebon terasi to the consommé containing fish terasi. The results showed that upon adjusting the salt content, the consommé containing rebon terasi was more preferred than the consommé containing fish terasi. By combining more strong spices or ingredients the acceptance of consommé might be improved while masking the pungent odor of terasi. In addition, six different types of rebon terasi varying in proximate composition, salt and water activity (aw) were added to beef consommé and were evaluated by 10 trained panelists for their specific intensity of taste/flavor (saltiness, sourness, sweetness, bitterness, umami, fishy and rebon). Together with those samples, other consommés were also compared; however, the salt was also added to adjust with the highest salt content among six types of terasi. The results showed that variations of terasi influenced the sensory characteristics of consommé. The salt content of rebon terasi influenced the sourness, bitterness and saltiness in consommé, whilst the salt content should also reach the certain level to fit their acceptance. The distinct flavor from each terasi did have a profound effect on the sensory acceptability. The knowledge of the flavor characteristics of consommé and the role of terasi when mixed in consommé will help to improve the sensory acceptability and marketability of terasi.

scholarly journals Study of vacuum and freeze drying of bee honey

2020 ◽  
Vol 24 (6 Part B) ◽  
pp. 4241-4251
Author(s):  
Nebojsa Nedic ◽  
Milan Gojak ◽  
Ivan Zlatanovic ◽  
Nedzad Rudonja ◽  
Kristina Lazarevic ◽  
...  
Keyword(s):  
Water Activity ◽  
High Performance ◽  
Freeze Drying ◽  
Soluble Solids ◽  
Diffusivity Coefficient ◽  
Chromatography Method ◽  
Drying Time ◽  
Freeze Dried ◽  
Acacia Honey ◽  
The Impact

The aim of this research is to study the drying kinetics of vacuum-dried and freeze-dried bee honey produced from two different varieties: Sunflower honey (Helianthus Annuus L.) and Acacia honey (Robinia pseudo acacia L.). Vacuum drying treatments were carried out with the honey samples? initial temperatures of +25?C, ?20?C, and ?40?C. Water content, total soluble solids, as well as the water activity of fresh and dried honey samples were determined. Freeze-drying of bee honey with initial sample temperature of ?40?C has resulted in shorter drying time (7-9 hours), moisture content (10%-12%), water activity (0.405-0.427 aW) and effective moisture diffusivity coefficient (8.26?10?7-9.51?10-7 m2/s). The high-performance liquid chromatography method was used when analyzing the impact that drying pre-treatments had on honey quality. The application of pre-treatments has led to an increase in hydroxy-methyl-furfural by 39-71%, and a decrease in diastase activity by 17-36%, all compared to fresh honey samples. The solutions of Verma model proved to be the best fit with the experimental results.

Influence of low water activity on the thermal resistance of Salmonella Enteritidis PT30 and Enterococcus faecium as its surrogate in egg powders

2020 ◽  
pp. 108201322093787
Author(s):  
Marco E Pérez-Reyes ◽  
Xu Jie ◽  
Mei-Jun Zhu ◽  
Juming Tang ◽  
Gustavo V Barbosa-Cánovas
Keyword(s):  
Thermal Resistance ◽  
Linear Relationship ◽  
Water Activity ◽  
Enterococcus Faecium ◽  
Salmonella Enteritidis ◽  
Thermal Treatments ◽  
Thermal Death ◽  
Industrial Food Production ◽  
Log Linear ◽  
The Impact

Egg powders are increasingly popular ingredients, due to their functionality and compactness, in industrial food production and preparation at homes. However, there is a lack of studies that evaluate the thermal resistance of Salmonella Enteritidis PT30 and its potential surrogate Enterococcus faecium NRRL B-2354 in egg powders. This study examined the log-linear relationship between the thermal resistance of Salmonella Enteritidis (D-value) and the water activity (aw) of egg powders. The changes of aw in the egg powders with temperature were measured using a Vapor Sorption Analyzer and a high-temperature cell. The D80 ℃-value of S. Enteritidis PT30 and E. faecium inoculated in the egg powders preconditioned to three aw levels (0.3, 0.45, and 0.6) at 20 ℃ were determined using aluminum thermal death test cells. The aw values increased (P < 0.05) in all three egg powders when the temperature of the samples was raised from room temperature to 80 ℃. The D80 ℃-values ranged from 5.3 ± 0.1 to 25.9 ± 0.2 min for S. Enteritidis while 10.4 ± 0.4 to 43.8 ± 0.4 for E. faecium in samples of the three different aw levels. S. Enteritidis PT30 showed a log-linear relationship between D80 ℃-values and aw80 ℃ for the egg powders. This study contributes to our understanding of the impact of aw on the development of thermal treatments for low-moisture foods.

The Impact of Water Activity on Storage Stability of a Newly Reformulated Salami A pilot scale study

2017 ◽  
Vol 68 (4) ◽  
pp. 763-767 ◽  
Author(s):  
Cristian Tudose ◽  
Corina Neagu ◽  
Daniela Borda ◽  
Petru Alexe
Keyword(s):  
Relative Humidity ◽  
Water Activity ◽  
Bound Water ◽  
Thiobarbituric Acid ◽  
Weibull Model ◽  
Pilot Scale ◽  
Water Characteristics ◽  
Colour Changes ◽  
Modified Weibull ◽  
The Impact

Two formulations of salami were obtained: a conventional salami (50 % beef, 20 % pork and 30 % animal fat, w/w) and a reformulated one (50 % beef, 20 % pork and 30 % a mixture of olive and palm oil - 2.5:1, w/w). Storage studies were performed by accelerated shelf life testing at 20�C and different relative humidity, in comparison with 4 and 8�C after 22 days of storage. Halsey model was the best one to describe the desorption isotherms. The products stability was evaluated by TBA (thiobarbituric acid) index and colour changes. TBA increased with the increase of the environment relative humidity at 4 and 8�C. Modified Weibull model described the changes in colour as a function of TBA and water activity. Bound water characteristics have markedly changed at 20�C for both products. The results of this work can be used as reference in defining reformulated salami minimal durability.

scholarly journals Comparing Nonsynergy Gamma Models and Interaction Models To Predict Growth of Emetic Bacillus cereus for Combinations of pH and Water Activity Values

2011 ◽  
Vol 77 (16) ◽  
pp. 5707-5715 ◽  
Author(s):  
Elisabeth G. Biesta-Peters ◽  
Martine W. Reij ◽  
Marcel H. Zwietering ◽  
Leon G. M. Gorris
Keyword(s):  
Experimental Data ◽  
Bacillus Cereus ◽  
Water Activity ◽  
Systematic Approach ◽  
Test Organism ◽  
Limiting Factors ◽  
Gamma Model ◽  
Content Type ◽  
The Individual ◽  
The Impact

ABSTRACTThis research aims to test the absence (gamma hypothesis) or occurrence of synergy between two growth-limiting factors, i.e., pH and water activity (aw), using a systematic approach for model selection. In this approach, preset criteria were used to evaluate the performance of models. Such a systematic approach is required to be confident in the correctness of the individual components of the combined (synergy) models. WithBacillus cereusF4810/72 as the test organism, estimated growth boundaries for the aw-lowering solutes NaCl, KCl, and glucose were 1.13 M, 1.13 M, and 1.68 M, respectively. The accompanying awvalues were 0.954, 0.956, and 0.961, respectively, indicating that equal awvalues result in similar effects on growth. Out of the 12 models evaluated using the preset criteria, the model of J. H. T. Luong (Biotechnol. Bioeng. 27:280–285, 1985) was the best model to describe the effect of awon growth. This awmodel and the previously selected pH model were combined into a gamma model and into two synergy models. None of the three models was able to describe the combined pH and awconditions sufficiently well to satisfy the preset criteria. The best matches between predicted and experimental data were obtained with the gamma model, followed by the synergy model of Y. Le Marc et al. (Int. J. Food Microbiol. 73:219–237, 2002). No combination of models that was able to predict the impact of both individual and combined hurdles correctly could be found. Consequently, in this case we could not prove the existence of synergy nor falsify the gamma hypothesis.

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