scholarly journals Fungal Population of Nutmeg (Myristica fragrans) Kernels Affected by Water Activity During Storage

2018 ◽  
Vol 37 (3) ◽  
pp. 288
Author(s):  
Kiki Nurtjahja ◽  
Okky Setyawati Dharmaputra ◽  
Winiati Pudji Rahayu ◽  
Rizal Syarief
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
Penicillium Citrinum ◽  
Dilution Method ◽  
Salt Solutions ◽  
Fungal Population ◽  
Plate Method ◽  
North Sulawesi ◽  
Duration Of Storage ◽  
Serial Dilution Method

The aim of this investigation was to determine the effect of various water activities (aw) on fungal population in nutmeg kernels during storage. The seed nutmegs were obtained from ripe fruits one week after they fell on the ground in North Minahasa Regency, North Sulawesi Province, Indonesia. The kernels (moisture content ± 10%) were stored 0, 15, and 30 days in various aw (0.75, 0.80, 0.83, 0.90, 0.97) using saturated salt solutions at 29 °C in sorption containers. Serial dilution method followed by a pour-plate method in Dichloran 18% Glycerol Agar (DG18) was used to isolate and quantify the fungal population. Results revealed that kernels stored at aw = 0.75 was not significantly (p < 0.05) different from at aw = 0.80-0.83. Fungal population of kernels determined  aw and significantly (p < 0.05) influenced by duration of storage. Range of aw 0.80-0.83 has a smaller total fungal population than aw ≥ 0.90. Thirteen different genera/species were isolated and identified including Aspergillus and Eurotium (6 species), Penicillium (3 species), Fusarium (2 species), 1 species each of Cladosporium or Syncephalastrum, and isolate A. The largest total fungal population (5.0×105 CFU g-1) was present at the beginning of storage (aw = 0.97) and it was dominated by Penicillium citrinum (2.6×105 CFU g-1) followed by Cladosporium cladosporioides (1.7×105 CFU g-1). After 30 days of storage (aw = 0.97) the population of P. citrinum was still dominant with a population of 2.4×104 CFU g-1. Eurotium chevalieri followed with a population of 1.2×104 CFU g-1.

scholarly journals Dry season and diurnal surveys of phylloplane fungi of Hevea brasiliensis in Nigeria

2014 ◽  
Vol 23 (1) ◽  
pp. 143-147
Author(s):  
J. A. Okhuoya ◽  
C. O. Ahweyevu
Keyword(s):  
Hevea Brasiliensis ◽  
Fungal Spores ◽  
Dry Season ◽  
Dilution Method ◽  
Fungal Population ◽  
Peak Period ◽  
Mature Leaves ◽  
Phylloplane Fungi ◽  
Young Leaves ◽  
Serial Dilution Method

Monthly and diurnal variation of phylloplane fungi of rubber (<i>Hevea brasiliensis</i>) leaves were studied over a period of four months in the dry season, using two culturing methods. Composite fungal population was the highest in April and the lowest in February. Serial dilution method recorded the higher number of fungal spores than ballistospore method. Mature leaves were found to have more fungal spores than premature and young leaves. Spore concentration on the leaves showed diurnal periodicity, with peak period of spores between 12-18 hr. Rubber leaves outside the plantation, had more spores on their surfaces than those shaded by the plantation canopy. The factors responsible for these observations were discussed.

scholarly journals Effect of Addition of Green Coffee Parchment on Structural, Qualitative and Chemical Properties of Gluten-Free Bread

Foods ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Paola Littardi ◽  
Massimiliano Rinaldi ◽  
Maria Grimaldi ◽  
Antonella Cavazza ◽  
Emma Chiavaro
Keyword(s):  
Moisture Content ◽  
Oxidative Stability ◽  
Water Activity ◽  
Chemical Properties ◽  
Antioxidant Compounds ◽  
Total Phenol Content ◽  
Green Coffee ◽  
Gluten Free ◽  
Wet Processing ◽  
Total Antioxidant

Green coffee parchment (GCP) is becoming interesting, due to the diffusion of wet processing in which coffee parchment is collected separately; it is one of the less studied coffee by-products, but it is reported to be rich in phenolic compounds and dietary fiber. The addition of GCP (355–500 μm) at 2 % to gluten-free breads was investigated in terms of physical properties (volume, moisture content, water activity, crumb grain, texture, and color), total antioxidant capacity (TAC) and total phenol content during three days of storage. Moreover, the effects of GCP on sensorial characteristics, 5-hydroxymethylfurfural (HMF), and oxidative stability was evaluated. From the sensorial analysis, bread with 2% addition resulted in being acceptable for consumers with no significant differences from the control, while 4% of GCP was discarded by consumers, as it resulted in being too bitter. Moreover, GCP at 2% addition did not modify volume, moisture content, and water activity. On the contrary, GCP deeply affected the color with a darker aspect that was appreciated by consumers. Regarding texture, 2% of GCP did not affect hardness, cohesiveness, and staling process during storage. Interestingly, 2% of GCP significantly improved the TAC and oxidative stability of the bread; in accordance with these results, 2% of GCP reduced the HMF content, thanks to its antioxidant compounds.

Equilibrium moisture content of dead fine fuels of selected central European tree species

2013 ◽  
Vol 22 (6) ◽  
pp. 797 ◽  
Author(s):  
Christian Schunk ◽  
Clemens Leutner ◽  
Michael Leuchner ◽  
Clemens Wastl ◽  
Annette Menzel
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Input Parameter ◽  
Fire Danger ◽  
Pedunculate Oak ◽  
Salt Solutions ◽  
Test Procedures ◽  
Climate Chamber ◽  
Central European ◽  
Fine Fuels

Fine fuel moisture content is a key parameter in fire danger and behaviour applications. For modelling purposes, equilibrium moisture content (EMC) curves are an important input parameter. This paper provides EMC data for central European fuels and adds methodological considerations that can be used to improve existing test procedures. Litter samples of Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), European beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.) were subjected to three different experiments using conditioning in a climate chamber and above saturated salt solutions. Climate chamber conditioning yielded the best results and can generally be recommended, however saturated salt solutions are able to produce lower relative humidities, which are relevant to forest fire applications as they represent the highest fire danger. Results were within the range of published sorption isotherms for forest fine fuels. A fairly clear gradation was present with higher EMC values in leaf litters than in needle litters. These differences are in accord with values from the literature and suggest general differences in the sorption properties of leaves and needles, which may be caused by differing chemical and physical properties. The influence of temperature on EMC described in the literature could be confirmed.

Microwave Nondestructive Sensing of Moisture Content and Water Activity of Almonds

2021 ◽  
Vol 64 (4) ◽  
pp. 1373-1379
Author(s):  
Samir Trabelsi
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Moisture Content ◽  
Bulk Density ◽  
Water Activity ◽  
Free Space ◽  
Loss Factor ◽  
Dielectric Loss Factor ◽  
List Type

HighlightsMoisture and water activity were determined nondestructively and in real time from measurement of dielectric properties.Moisture and water activity calibration equations were established in terms of the dielectric properties.Situations in which bulk density was known or unknown were considered.SEC ranged from 0.41% to 0.68% for moisture and from 0.02 to 0.04 for water activity.Abstract. A method for rapid and nondestructive determination of moisture content and water activity of granular and particulate materials was developed. The method relies on measurement of the dielectric constant and dielectric loss factor at a single microwave frequency. For the purpose of illustration, the method was applied to predicting the moisture content and water activity of almond kernels. A free-space transmission technique was used for accurate measurement of the dielectric properties. Samples of Bute Padre almond kernels with moisture content ranging from 4.8% to 16.5%, wet basis (w.b.), and water activity ranging from 0.50 to 0.93 were loaded into a Styrofoam sample holder and placed between two horn-lens antennas connected to a vector network analyzer. The dielectric properties were calculated from measurement of the attenuation and phase shift at 8 GHz and 25°C. The dielectric properties increased linearly with moisture content, while they showed an exponential increase with water activity. Situations in which the bulk density was known and unknown were considered. Linear and exponential growth regressions provided equations correlating the dielectric properties with moisture content and water activity with coefficients of determination (r2) higher than 0.96. Analytical expressions of moisture content and water activity in terms of the dielectric properties measured at 8 GHz and 25°C are provided. The standard error of calibration (SEC) was calculated for each calibration equation. Results show that moisture content can be predicted with SECs ranging from 0.41% to 0.68% (w.b.) and water activity with SECs ranging from 0.02 to 0.04 for almond kernel samples with water activity ranging from 0.5 to 0.9 and moisture contents ranging from 4.8% to 16.5% (w.b.). Keywords: Bulk density, Dielectric constant, Dielectric loss factor, Free-space measurements, Loss tangent, Microwave frequencies, Moisture content, Water activity.

scholarly journals Changes in Fungal Population and Aflatoxin Levels and Assessment of Major Aflatoxin Types in Stored Peanuts (Arachis hypogaea Linnaeus)

2013 ◽  
Vol 2 (5) ◽  
pp. 10 ◽  
Author(s):  
John Maina Wagacha ◽  
Charity K. Mutegi ◽  
Maria E. Christie ◽  
Lucy W. Karanja ◽  
Job Kimani
Keyword(s):  
Moisture Content ◽  
Aflatoxin B1 ◽  
Fungal Pathogens ◽  
Aflatoxin Contamination ◽  
Fungal Population ◽  
Total Aflatoxin ◽  
Regulatory Standards ◽  
Polyethylene Bags ◽  
Jute Bags ◽  
The Eu

<p>Peanut kernels of Homabay Local, Valencia Red, ICGV-SM 12991 and ICGV-SM 99568 cultivars were stored for six months in jute, polypropylene and polyethylene bags to assess the effect of storage bags, temperature and R.H. on fungal population and aflatoxin contamination. Moisture content (M.C.), fungal population and aflatoxin levels were determined before storage and after every 30 days during storage. Isolates of <em>Aspergillus flavus</em> and <em>A. parasiticus</em> were assayed for production of aflatoxin B1, B2, G1 and G2. The correlation between MC, population of <em>A. flavus</em> and <em>A. parasiticus</em> and aflatoxin levels in peanuts was also determined. Six fungal pathogens were commonly isolated from the peanut samples and occurred as follows in decreasing order: <em>Penicillium</em> spp. (106.6 CFU/g), <em>A. flavus</em> L-strain (4.8 CFU/g), <em>A. flavus</em> S-strain (2.9 CFU/g), <em>A. niger </em>(2.6 CFU/g), <em>A. parasiticus </em>(1.7 CFU/g) and <em>A. tamarii </em>(0.2 CFU/g). The overall population of <em>A. flavus</em> L-strain was 66% higher than that of <em>A. flavus</em> S-strain. Ninety one percent of <em>A. flavus</em> and <em>A. parasiticus</em> isolates produced at least one of the four aflatoxin types assayed, with 36% producing aflatoxin B1. Total aflatoxin levels ranged from 0 - 47.8 µg/kg with samples stored in polyethylene and jute bags being the most and least contaminated, respectively. Eighty nine percent and 97% of the peanut samples met the EU (? 4 µg/kg) and Kenyan (? 10 µg/kg) regulatory standards for total aflatoxin, respectively. Peanuts should be adequately dried to safe moisture level and immediately packaged in a container - preferably jute bags - which will not promote critical increases in fungal population and aflatoxin contamination.</p>

scholarly journals CURVAS DE SECAGEM E AVALIAÇÃO DA ATIVIDADE DE ÁGUA DA BANANA PASSA

2004 ◽  
Vol 22 (1) ◽  
Author(s):  
MILTON CANO-CHAUCA ◽  
AFONSO M. RAMOS ◽  
PAULO C. STRINGHETA ◽  
JOSÉ ANTONIO MARQUES ◽  
POLLYANNA IBRAHIM SILVA
Keyword(s):  
Experimental Data ◽  
Linear Regression ◽  
Moisture Content ◽  
Water Activity ◽  
Linear Regression Analysis ◽  
Sorption Isotherms ◽  
Exponential Model ◽  
Drying Time ◽  
Non Linear ◽  
Drying Curves

Curvas de secagem de banana passa foram determinadas, utilizando-se três temperaturas do ar de secagem. Os resultados indicaram que para reduzir o teor de umidade do produto até 23,5% foram necessários tempos de secagem de 51, 36 e 30 horas paras as temperaturas de 50, 60 e 70ºC, respectivamente. O modelo exponencial U/Uo = exp(-kt) foi ajustado para os dados experimentais mediante análise de regressão não-linear, encontrandose alto coeficiente de regressão linear. Determinou-se a atividade de água do produto ao longo do processo de secagem para as três temperaturas testadas. Estudou-se a correlação entre a atividade de água e o teor de umidade do produto, determinando-se as isotermas de dessorção da banana passa a 25ºC. Observou-se que a atividade de água diminuiu em função do tempo de secagem e do teor de umidade para as três temperaturas de secagem. Os dados experimentais foram ajustados mediante regressão não-linear ao modelo polinomial e a seguinte equação foi obtida: U = -1844,93 + 7293,53Aa – 9515,52Aa2 + 4157,196Aa3. O ajuste mostrou-se satisfatório (R2 > 0,90). DRYING CURVES AND WATER ACTIVITY EVALUATION OF THE BANANA-PASSES Abstract Banana drying curves were determined by utilizing three drying air temperatures. The results indicated that to reduce the moisture content of the product until 23.5% it were necessary drying times of 51, 36 and 30 hours for temperatures of 50, 60 and 70ºC, respectively. The exponential model U/Uo = exp(-kt) was adjusted for the experimental data by means of non linear regression analysis, and a high coefficient of linear regression was found. The water activity of the product was determined throughout the drying process for the three tested temperatures. The correlation between the water activity and moisture content of the product was studied, and the sorption isotherms were determined at 25º C. It was observed that the water activity decreased in function to the drying time and moisture content for the three drying temperatures. The experimental data were adjusted by means of non linear regression to the polynomial model and the following equation was obtained: U = - 1844.93 + 7293.53A a – 9515.52 Aa 2 + 4157.196A a 3. The final adjust was satisfactory (R2 > 0.90).

The Structure and Antibacterial Activity of Taurine and its Magnesium Complex

2011 ◽  
Vol 366 ◽  
pp. 404-407
Author(s):  
Li Hua Wang
Keyword(s):  
Escherichia Coli ◽  
Antibacterial Activity ◽  
Bacillus Subtilis ◽  
Single Crystal ◽  
Dilution Method ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Antibacterial Assay ◽  
Serial Dilution Method

The block single-crystals of taurine were obtained, and its structure was determined by single-crystal X-ray diffraction. The single-crystal X-ray analysis of taurine reveals that the crystal belongs monoclinic, space group P2(1)/c with a = 0.52824(10) nm, b = 1.1647(8) nm, c = 0.79236(13) nm, ß = 94.0850(10). The magnesium complex with taurine has been synthesized in ethanol. The antibacterial assay of the Mg (II) complex was measureed using a modified version of the 2-fold serial dilution method. The results show that the complex shows considerable antibacterial activity against escherichia coli, bacillus subtilis and staphylococcus white.

scholarly journals ANTIBIOTICS RESISTANCE OF CORYNEBACTERIUM NON DIPHTHERIAE STRAINS

2017 ◽  
pp. 3-8
Author(s):  
G. G. Kharseeva ◽  
N. A. Voronina ◽  
T. D. Gasretova ◽  
O. I. Sylka ◽  
S. Yu. Tyukavkina
Keyword(s):  
Serial Dilution ◽  
Urogenital Tract ◽  
Antibiotics Resistance ◽  
Dilution Method ◽  
Frequency Of Occurrence ◽  
Serial Dilution Method ◽  
Resistant Strains

Aim. Study the frequency of occurrence of antibiotics resistant strains of various species of Corynebacterium non diptheriae. Materials and methods. C.pseudodiphtheriticum, C.pseudotuberculosis, C.xerosis, C.amycolatum, C.striatum, C.ulcerans strains isolated from patients with pathologies of respiratory and urogenital tract, as well as individuals taking prophylaxis examination were used. Sensitivity to antibacterial preparations was determined by the serial dilution method. Results. The highest number of Corynebacterium non diptheriae strains displayed resistance to benzylpenicillin (54.8%) and lincomycin (50.7%), and lowest - to cefotaxime, cefazolin (6.8%) and vancomycin (13.7%). The highest number of antibiotics resistant strains were detected among members of C.pseudotuberculosis {100%), C.xerosis (96.0%) and C. pseudodiphtheriticum (81.0%) species. Polyresistant strains were detected most frequently among C.xerosis, C.amycolatum and C.striatum species. Strains of Corynebacterium non diptheriae most frequently displayed resistance to 1 or 2 antibacterial preparations (24.7%), less frequently - to 3 (20.5%), 4 (13.7%), 5 (4.1%) and 6 (1.4%) preparations. Conclusion. The amount of antibiotics resistant strains of Corynebacterium non diptheriae is large (89.0%) and non-similar in various species.

scholarly journals Sorption isotherms of Brazil nuts

2019 ◽  
Vol 23 (10) ◽  
pp. 776-781 ◽  
Author(s):  
Fernando M. Botelho ◽  
Nilso J. Boschiroli Neto ◽  
Silvia de C. C. Botelho ◽  
Gabriel H. H. de Oliveira ◽  
Michele R. Hauth
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Water Activity ◽  
Sorption Isotherms ◽  
Static Method ◽  
Acid Solutions ◽  
Brazil Nut ◽  
Brazil Nuts ◽  
Abstract Knowledge ◽  
Sorption Phenomenon

ABSTRACT Knowledge of the water sorption phenomenon in Brazil nut seeds will allow proper handling of this product, especially with regard to adequate conditions for safe storage. Thus, the present study aimed to determine the sorption isotherms (desorption and adsorption) of Brazil nuts, fitting different mathematical models to the experimental data, as well as to examine the hysteresis effect. To obtain the sorption isotherms, the static method was employed at temperatures of 25, 35, 45 and 55 °C and air relative humidities varying from 10 to 80%. The psychrometric conditions of the air were acquired with the aid of acid solutions and specific saturated saline left inside desiccators with the samples. It was verified that for a given isotherm, the equilibrium moisture content of Brazil nuts increases with water activity increment. In addition, at a constant water activity, equilibrium moisture content decreases with temperature increase. The Copace, Henderson and Oswin are the models that best describe the hygroscopicity of the Brazil nut seed for both the adsorption and desorption processes. Hysteresis was more pronounced at lower temperatures and higher values of water activity. The moisture content value for storage at temperatures less than 55 °C, without the risk of fungal development, must be lower than 8.2% (d.b.).

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