Projecte llegit

Títol: Impacto de la crioconcentración asistida por vacío de leche sin lactosa

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Tutor/a o Cotutor/a: HERNANDEZ YAÑEZ, EDUARD

Departament: DEAB

Títol: Impacto de la crioconcentración asistida por vacío de leche sin lactosa

Data inici oferta: 30-01-2020      Data finalització oferta: 30-09-2020

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Estudis d'assignació del projecte:

MU MKET4FOOD+BIO

Lloc de realització:
EEABB

Paraules clau:
Vacuum-assisted block; freeze concentration; lactose-free skimmed milk

Descripció del contingut i pla d'activitats:
La crioconcentración es una tecnología emergente para la
concentración de alimentos. Los lácteos sin lactosa pueden
proporcionar los nutrientes esenciales presentes en los
productos lácteos regulares, como el calcio y las vitaminas, a
aquellos que no pueden digerir la lactosa. Los lácteos sin
lactosa son ahora el mercado de más rápido crecimiento en la
industria láctea.
La principal ventaja de la crioconcentración es que permite
preservar las propiedades organolépticas de los alimentos. En
este trabajo de final de máster se propone emplear la
crioconcentración en bloque asistida por vacío en la
concentración de leche sin lactosa. En nuestro conocimiento no
se tiene constancia de ningún trabajo previo de este tipo. Se
pretende analizar la influencia de la presión y tiempo de
vacío sobre el rendimiento de la crioconcentración

Overview (resum en anglès): Vacuum-assisted block freeze concentration is a technique that allows producing higher quality and more concentrated solutions than concentration by evaporation or other conventional methods.
In this study, the influence of applying vacuum-assisted block freeze concentration method to lactose-free skimmed UHT cow milk was studied.
Two kinds of milk were investigated to evaluate the freezing points of lactose-free milk and normal milk at different concentrations.
The influence of factors Freezing Time (FT), Vacuum Time (VT), and Vacuum Pressure (VP) on Soluble Solids Recovery Percentage (Y%), and Percentage of Efficiency of Concentration (EFF%) through the statistical tool of Design of Experiments (DOE) using Minitab 19 software was studied.
An initial evaluation of the process conditions was found by carrying out 24 Full Factorial Design (FFD). The studied variables were Freezing Time (12 and 24 h), Vacuum Time (30 and 60 min), and Vacuum Pressure (10 and 70 kPa). Afterward, the system's optimization was explored by employing the Response Surface Methodology through a Central Composite Design by adding central and axial points to the previous Full Factorial Design, which were 18 h for Freezing Time, 45 min for Vacuum Time, and 45 kPa for Vacuum Pressure. In total, 60 experiments were carried out divided into 24 factorial points, 18 central points, and 18 axial points.
By applying the Full Factorial Design method to the factorial points, it was observed that vacuum time and vacuum pressure significantly affected response variables: soluble solids recovery percentage and percentage of efficiency of concentration. In contrast, the freezing time has no significant effect on response variables.
The final experiment results showed a significant solute increase in concentrated fraction compared to the initial samples. The best result was obtained under 24 h of freezing time, 60 min of vacuum time, and 10 kPa of vacuum pressure with a content of 35.7 °Bx, which is a more than three-fold increase over the initial fresh milk with a total soluble solids content of 10.9 °Bx.
It was discovered through the response optimization that, by applying vacuum pressure of 10 kPa, and vacuum time of 60 min, the highest soluble solids content percentage (79.48%) at 19 h of freezing time and efficiency of concentration percentage (91.10%) at 20 h of freezing time will be achievable.
By comparing the valuable components between the initial fresh sample and the concentred sample, a remarkable increase of proteins (2.26 times) and carbohydrates (2.6 times) were shown. Consequently, vacuum-assisted block freeze concentration was an effective technique to maintain and increase the lactose-free skimmed milk's valuable components.

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