The attempt is covered with silicone fat to water resistant the material. Visible frequency was counted which have a great steropycnometer ( Loch-Bonazzi while some 1992 ).
Present, very exact tips for calculating apparent volume had been suggested, also laserlight researching ( Uyar and you can Erdogdu 2009 ; Kelkar while others 2011 ), computerized tomography ( Mendoza while some 2007 ; Kelkar and others 2011 ), and you may magnetized resonance imaging ( Kelkar while some 2011 ). Such process incorporate optic equipment and certified software so you can process and do 3d photos away from items, calculating volume with limited differences or finite element. Although not, the fresh new downsides of these process surpass the pros, since the a specific records is necessary, also authoritative gadgets that’s significantly more high priced than simply conventional procedure.
Collection out of Studies
A great amount of performs has actually handled the brand new decisions away from correct and noticeable thickness, both in new drying techniques along with the fresh new rehydration regarding foodstuffs (Desk step 1 and 2). This research evaluate several ingredients confronted with individuals drying criteria and you will in various geometric shapes. The fresh new variables that have been learnt are as follows: tension (P), cousin moisture (RH), drying air velocity (?), and you will drying out temperature (T), and others. Pretreatments like blanching, coatings, and you may osmotic dehydration, yet others, was advertised ( Boukouvalas and others 2006 ).
Old-fashioned convective drying out, microwave oven drying out, osmotic drying out, spray-drying, vacuum-drying out, and you may lyophilization are the most commonly used procedures; these include examined less than each other constant and you may changeable performing standards ( Pezzutti and you can C ; Doymaz and you may Pala 2002 ). Material dried of the convective approach are described as the low porosity and you can large noticeable density ( Zogzas and others 1994 ). Equivalent services was basically claimed for product dried into microwave oven approach, due to the fact that a mixture of this type of dos strategies are used ( Krokida and others 2000 ). Osmotic dehydration causes an increase in visible thickness for some materials, and you can a decline for other individuals. So it experience has been caused by the increase sites de rencontres américano mexicains when you look at the solids throughout the the newest osmotic techniques ( Krokida and Maroulis 1997 ). Lyophilization efficiency situations having low occurrence, employing porosity; this process produces the highest quality final result, and there’s no deformations from the matter, color and you can scent are managed. Still, it does have the disadvantage to be expensive and you may requiring enough time drying periods ( Krokida and you may ).
Multiple structural details regarding food items was basically evaluated inside the lyophilization processes. Sablani while others (2007) learned that visible thickness, genuine thickness, and you may porosity was a purpose of water blogs (X) and you will dish temperatures; however, there is certainly too little clarity throughout these tendencies ( Karathanos and others 1996 ; Sablani although some 2007 ; Oikonomopoulou although some 2011 ).
The effects from drying criteria towards density
Some people have discovered that aftereffect of relative humidity toward genuine and you can apparent density are minimal ( Zogzas while others 1994 ). As the results of drying heavens acceleration towards thickness have not already been studied, you can amass research out-of some bibliographic provide it comes down to one material; such as for example study suggest that correct and you can noticeable thickness try all the way down within straight down drying air velocities (Table step one). not, further search on the topic is necessary. Partners research has reported towards the outcomes of the latest geometry off the material toward thickness, though it has been seen so you’re able to dictate apparent occurrence viewpoints. For example, the brand new density off entire garlic cloves enjoys an effective concave-down contour in terms of X; alternatively, garlic cloves chopped in half screen a great linear, ascendant interest according to reduced total of X ( Lozano while some 1983 ).