Effect of culture age, protectants, and initial cell concentration on viability of freeze-dried cells ofMetschnikowia pulcherrima

2010 ◽  
Vol 56 (10) ◽  
pp. 809-815 ◽  
Author(s):  
Davide Spadaro ◽  
Annalisa Alessandra Ciavorella ◽  
Jorge Giovanny Lopez-Reyes ◽  
Angelo Garibaldi ◽  
Maria Lodovica Gullino
Keyword(s):  
Freeze Drying ◽  
Cell Concentration ◽  
Yeast Cells ◽  
Initial Cell Concentration ◽  
Commercial Development ◽  
Culture Age ◽  
Biocontrol Efficacy ◽  
High Viability ◽  
Freeze Dried ◽  
Drying Conditions

The effect of freeze-drying using different lyoprotectants at different concentrations on the viability and biocontrol efficacy of Metschnikowia pulcherrima was evaluated. The effects of initial yeast cell concentration and culture age on viability were also considered. Yeast cells grown for 36 h were more resistant to freeze-drying than were 48 h cells. An initial concentration of 108cells·mL–1favoured the highest survival after freeze-drying. When maltose (25%, m/v) was used as protectant, a high cell viability was obtained (64.2%). Cells maintained a high viability after 6 months of storage at 4 °C. The biocontrol efficacy of freeze-dried cells was similar to the activity of fresh cells on ‘Gala’ apples and was slightly lower on ‘Golden Delicious’ apples. After optimizing freeze-drying conditions, the viability of M. pulcherrima cells was similar to that obtained in other studies. The results constitute a first step towards the commercial development of M. pulcherrima as a biocontrol agent.

scholarly journals Encapsulation of peach waste extract in Saccharomyces cerevisiae cells

2021 ◽  
pp. 1-1
Author(s):  
Dragoljub Cvetkovic ◽  
Aleksandra Ranitovic ◽  
Vanja Seregelj ◽  
Olja Sovljanski ◽  
Jelena Vulic ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Encapsulation Efficiency ◽  
Freeze Drying ◽  
Cell Structure ◽  
Natural Antioxidants ◽  
Yeast Cells ◽  
Ecological Problem ◽  
Freeze Dried ◽  
Excellent Method ◽  
Valuable Compounds

As a secondary industry product, peach waste (PW) presents an ecological problem, but a potentially rich source of natural antioxidants. A potential and novel way to improve the phytochemical stability of waste rich in phytochemicals is encapsulation in yeast cells which possess good structure characteristics. In the present study, PW extract was encapsulated in non-plasmolyzed, plasmolyzed, and living Saccharomyces cerevisiae cells by freeze-drying method. HPLC analysis revealed that ?-carotene is the most abundant carotenoid, while epicatechin and catechin are the most abundant phenolics in PW. The highest encapsulation efficiency of carotenoids (86.59%), as well as phenolics (66.98 %), was obtained with freeze-dried non-plasmolyzed yeast cells used as carriers. Although plasmolysis can cause some changes in yeast cell structure and properties, it did not enhance the encapsulation efficiency of present phytochemicals. Successful encapsulation of PW extract in yeast cells was confirmed by FTIR spectroscopy and SEM imaging. The obtained results present the encapsulation of sensitive compounds in yeast cells by freeze-drying as an excellent method for preserving valuable compounds and their potential use in the food and pharmaceutical industry.

scholarly journals Evaluation of freeze-drying conditions on the process kinetics and physicochemical properties of purple shallot

Food Research ◽  
2020 ◽  
Vol 4 (5) ◽  
pp. 1630-1636
Author(s):  
N.M. Thuy ◽  
N.T.M. Tuyen ◽  
N.V. Thanh ◽  
N.V. Tai
Keyword(s):  
Moisture Content ◽  
Freeze Drying ◽  
Chemical Properties ◽  
Sample Pretreatment ◽  
Freezing Temperature ◽  
Moisture Diffusivity ◽  
Freezing Time ◽  
Freeze Dried ◽  
Thin Layer Drying ◽  
Drying Conditions

Purple shallot is an important vegetable crop in Vietnam and throughout the world. Its storage is difficult hence, it is dehydrated for value addition. Freeze drying is one of the options for dehydration of purple shallot. There are two main stages (freezing and drying) in the complete freeze-drying process after sample pretreatment. In this study, the sample was frozen at different temperatures and times (-20 to -60oC and 5 to 9 hrs, respectively). Controlling the selected temperature (from the second stage) and pressure 0.001 mbar, eight thin layer drying models were fitted to the experimental moisture content. The physical and chemical properties and antioxidant capacity of freeze-dried purple shallot were evaluated. The obtained results showed that the TPC values and DPPH% almost increased as the freezing time increased at the same freezing temperature. The best drying conditions were found at a freezing time of 7 hrs, freezing temperature of -60oC, a pressure of 0.001 mbar, and a lyophilization time of 12 hrs. Under these conditions, the moisture content, TPC and DPPH% of the final product were 1.56%, 16.95 mg GAE/g and 65.67%, respectively. Among the models proposed, Page's model gave a better fit for the freeze-drying condition used. In freeze-drying, effective moisture diffusivity was estimated to be 5.68×10-7 m 2 /s within the conditions studied.

scholarly journals The Impact of Freeze-Drying Conditions on the Physico-Chemical Properties and Bioactive Compounds of a Freeze-Dried Orange Puree

Foods ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 32 ◽  
Author(s):  
Marilú A. Silva-Espinoza ◽  
Charfedinne Ayed ◽  
Timothy Foster ◽  
María del Mar Camacho ◽  
Nuria Martínez-Navarrete
Keyword(s):  
Vitamin C ◽  
Water Content ◽  
Freeze Drying ◽  
Low Pressure ◽  
High Water Content ◽  
Freeze Dried ◽  
Drying Conditions ◽  
The Impact ◽  
Shelf Temperature ◽  
Β Carotene

Fruits are essential for a healthy diet, as they contribute to the prevention of cardiovascular diseases and some cancers, which is attributed to their high bioactive compound content contributing to their antioxidant capacity. Nevertheless, fruits have a short shelf life due to their high-water content, and freeze-drying is a well-known technique to preserve their nutritive quality. However, it is an expensive technology, both due to the use of low pressure and long processing time. Therefore, an optimisation of variables such as the freezing rate, working pressure and shelf temperature during freeze-drying may preserve fruit quality while reducing the time and costs. The impact of these variables on colour, porosity, mechanical properties, water content, vitamin C, total phenols, β-carotene, and antioxidant activity of a freeze-dried orange puree was evaluated. The results showed a great impact of pressure and shelf temperature on luminosity, chroma and water content. Vitamin C and β-carotene were more preserved with higher shelf temperatures (shorter times of processing) and lower pressure, respectively. The optimum freeze-drying conditions preserving the nutrients, and with an interesting structural property, perceived as a crunchy product by consumers, are low pressure (5 Pa) and high shelf temperature (50 °C).

Impact of freeze‐drying conditions on the sensory perception of a freeze‐dried orange snack

2021 ◽  
Author(s):  
Marilú Andrea Silva‐Espinoza ◽  
Ana Salvador ◽  
María del Mar Camacho ◽  
Nuria Martínez‐Navarrete
Keyword(s):  
Freeze Drying ◽  
Sensory Perception ◽  
Freeze Dried ◽  
Drying Conditions

Influence of the Freeze-drying Conditions on the Physicochemical Properties and Grinding Characteristics of Kiwi

2020 ◽  
Vol 16 (1-2) ◽  
Author(s):  
Marek Domin ◽  
Dariusz Dziki ◽  
Sybilla Kłapsia ◽  
Agata Blicharz-Kania ◽  
Beata Biernacka ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Freeze Drying ◽  
Average Particle Size ◽  
Antioxidant Properties ◽  
Average Particle ◽  
Freeze Dried ◽  
Energy Indices ◽  
Dried Fruit ◽  
Phenolics Content ◽  
Drying Conditions

AbstractThe aim of this work was to study the influence of freeze-drying conditions of kiwi (Actinidia deliciosa) on physicochemical properties and grinding characteristics of dried fruits. Whole kiwi fruits were freeze-dried with the different pressure: 12, 20, 42, 63, 85, and 103 Pa. Dried fruit properties that underwent evaluation included color, texture, rehydration, total phenolics content, antioxidant properties and sensory analysis. Moreover, the grinding energy indices of dried kiwi were determined. The results showed that an increase in the pressure caused decreased lightness, but increased yellowness and greenness of freeze-dried kiwi. The force of kiwi penetration increased and the rehydration ability decreased with the increase in the pressure. The specific grinding energy of dried kiwi ranged from 10.1 to 13.6 kJ⋅kg−1, whereas the average particle size of kiwi powder changed from 0.331 to 0.337 mm. The highest values of these parameters were obtained for kiwi freeze-dried with the highest pressure.

scholarly journals Carbon-to-Nitrogen Ratio and Carbon Loading of Production Media Influence Freeze-Drying Survival and Biocontrol Efficacy of Cryptococcus nodaensis OH 182.9

2005 ◽  
Vol 95 (6) ◽  
pp. 626-631 ◽  
Author(s):  
Shouan Zhang ◽  
David A. Schisler ◽  
Michael J. Boehm ◽  
Patricia J. Slininger
Keyword(s):  
Biomass Production ◽  
Freeze Drying ◽  
Kernel Weight ◽  
Gibberella Zeae ◽  
Total Biomass ◽  
Head Blight ◽  
Biocontrol Efficacy ◽  
Freeze Dried ◽  
The Difference ◽  
Carbon Loading

Fusarium head blight (FHB), caused by Gibberella zeae, is a devastating disease of wheat worldwide. Cryptococcus nodaensis OH 182.9 is an effective biocontrol agent for this disease. Development of a dried product of OH 182.9 would have potential advantages of ease of handling, favorable economics, and acceptance by end users. Isolate OH 182.9 was grown for 48 and 72 h in semi-defined complete liquid (SDCL) medium with carbon-to-nitrogen (C/N) ratios of 6.5:1, 9:1, 11:1, 15:1, and 30:1, and in SDCL C/N 30:1 media with varied carbon loadings of 7, 14, 21, and 28 g/liter. Total biomass production and cell survival at 15 days after freeze-drying were evaluated. Biomass production of OH 182.9 (CFU per milliliter) was not different for all cultivation time by medium C/N or carbon loading combinations. In general, cells harvested at 48 h survived freeze-drying better than those harvested at 72 h. Survival of freeze-dried cells was greatest for cells grown for 48 h in C/N30:1 medium. Cells produced in C/N 6.5:1 medium generally exhibited the poorest survival. For the C/N 30:1 media, cells from 7 g/liter carbon loading medium harvested after 48 h had the best survival after freeze-drying. The difference in freeze-dried cell populations between superior and inferior treatments was typically 1 to 2 log units at 15 days after freeze-drying. The biomass of OH 182.9 produced in SDCL with varied C/N ratios and in SDCL C/N 30:1 media with differing carbon loadings was tested for biocontrol efficacy against FHB in greenhouse studies. The biomass harvested from SDCL C/N 9:1, 11:1, and 15:1 media after 48 h significantly reduced symptoms of FHB. None of the treatments with cells harvested at 72 h consistently reduced FHB severity (P ≤ 0.05). Cells grown in SDCL C/N 30:1 media with 7 and 14 g/liter carbon loading significantly reduced FHB disease severity. Cells harvested from SDCL C/N 9:1, 11:1, and 30:1 with 14 g/liter carbon increased the 100-kernel weight compared with the disease control. The potential of improving OH 182.9 product quality via management of the nutritional environment of the production medium is demonstrated in this study.

scholarly journals Reeze-Drying Impact on Hardness of Selected Soft Fruit Liophilisates

2021 ◽  
Vol 25 (1) ◽  
pp. 135-146
Author(s):  
Marek Domin ◽  
Magdalena Ćwiklińska ◽  
Małgorzata Góral-Kowalczyk
Keyword(s):  
Freeze Drying ◽  
Grape Pomace ◽  
Raw Material ◽  
Pressing Process ◽  
Freeze Dried ◽  
Soft Fruit ◽  
Fruit Pomace ◽  
Drying Conditions ◽  
The Impact ◽  
Rotary Press

Abstract The objective of the paper was to describe the impact of freeze-drying conditions on hardness of lyophilizates obtained based on soft fruit pomace. Raspberry, cherry, and grape pomace from the pressing process carried out with a low-speed rotary press constituted a research material. Immediately after the pressing process, pomaces were placed in forms, frozen, and after freezing they were freeze-dried in the pressure of 20, 42, 63, 85 and 110 Pa. The obtained lyophilizates were subjected to the measurement of hardness with the use of texture meter equipped with a penetrometer in the form of a cone with a vertical angle of 30°. The increase of pressure during freeze-drying of samples was accompanied by the increase of hardness of the obtained lyophilizates, which may affect the energy consumption of the grinding process and the nature of rehydration of the final product. Moreover, the water content of raw material, pomaces, and lyophilizates was determined. The obtained results of measurements were subjected to a statistical analysis which showed that the pressure of freeze-drying significantly diversifies the hardness of the obtained lyophilizates.

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