• Yiyeceğin içeriğindeki nişastanın kırılması veya yumuşaması, selüloz, protein ve lifli yapının kırılması ile yemeğin daha yumuşak hale gelmesi sağlanır.
• Yemeği damak tadına uygun, sindirilebilir hale getirir.
• Besin zehirlenmesine yol açabilecek bakteri içeriğini yok ederek yemeği güvenilir hale getirir.
• Yemeğin kalitesini, rengini, lezzetini ve dokusunu
geliştirir. Metotlar Fırınlama yapılmadan önce fırın önceden
• Kuru ısıda fırınlama: Fırınlama yapılan yiyeceğin içindeki suyun buharlaşması ve fırın ısısı ile yiyecek pişer.
• Nemli ısıda fırınlama: Özellikle ekmek gibi gıdaların pişirilmesi sırasında nemi arttırmak için fırına su veya nem enjekte edilir, böylece yemeğin kalitesi artar.
• Isı değişimi ile: Pişirilecek yemeğin kabının altına su koyularak ısı değişimi sağlanır (ben-mari), yemek yavaş pişer. Özellikle de yumurtalı yemeklerin yanması önlenir.
Broiling ( Fırında Izgara )
Etlerin çabuk pişen yumuşak bölümleri veya çabuk pişen etler için uygundur.
Fırın sıcaklığı 400 F
F° = (9/5) x C° + 32
Fahrenheit cinsinden sıcaklığı Celcius’ a çevirirken aşağıdaki formül kullanılır.
C° = (5/9) x (F° – 32)
* Bütün ızgara ile pişirme yöntemlerinde ani şekilde yüksek ısıya maruz kalan etlerdeki proteinlerin yapısında meydana gelen değişikliklerle kanserojen maddeler ortaya çıkmaktadır.
Panbroiling
Frying ( Kızartma )
Deep Fat Frying:
Yiyeceklerin tamamen yağın içinde olduğu pişirme yöntemidir.
Yağ önceden ısıtılır. En ideali 175-190 C
Yağın içinde asla SU olmamalıdır.
Ayçiçek yağı- Yer fıstığı yağı- Hindistancevizi yağı kullanılabilir.
Yağın fazla ısınmasını engelleyin
Yangın önlemlerinizi alın
Yakınında sadece Metal ekipmanlar olmalı. Yangın anında alevler 2-3 metre yükselir
küçük doğranmış yiyecekler yüksek ısıda kısa süreli pişirme ile kıtır ve iyi pişmiş olur.
Büyük parçalar için uygun değildir.
Soğuk yiyeceklerin kullanımı daha uygundur.
Aynı anda çok fazla yiyecek kullanmayınız.
Pan – Frying ( Sauteing )
Tavada az miktarda yağ kullanarak doğranmış sebze ve etleri kızartma yöntemidir.
İlk önce tavayı ısıtınız.
Su olmamalı.
Yağ ekleyiniz. Yağ ısındıktan sonra yiyecekleri ekleyiniz.
Tavayı ateşten ayırmayınız.
Eğer soğan ve sarımsak aynı anda kullanılacaksa ilk önce soğanı tavaya atınız.
Kullanacağınız tüm ürünler önceden doğranmış olmalı.
DETERMINATION OF ACIDITY,PEROXIDE AND COLOR TEST OF FRIED OIL
PREPARED BY: ŞEYMA MARANGOZ
MEHTAP KEKLİK
İREM DEMET KODAŞ
DUYGU KÖKALP
EMİNE KÜÇÜKOĞLU
ŞEYMA KURTBEYOĞLU
SUBMITTED TO:PROF.DR.FAHRETTİN GÖĞÜŞ
WHAT IS THE FRYING?
WHAT ARE THE QUALITY TESTS IN FRIED OIL?
FRYING
Frying is the cooking of food in oil or another fat, a technique that originated in ancient Egypt around 2500 BC.
Frying is used to improve quality of taste and consummability of the food.
DEEP FRYING
Deep frying is a cooking method in which food is submerged in hot fat, most commonly oil.
Deep-frying is a cooking process, with which water containing foodstuff is immersed into edible oils or fats at temperatures between 140 – 180 °C.
In the first phase, within a few seconds, a thin crust forms, whose structure crucially affects the deep-frying process and the quality of the food with regards to fat absorption and crispness.
Factors Affecting the Quality of Oil during Deep Frying
Replenishment of fresh oil
Frying time and temperature
Quality of frying oil
Types of foods
Types of fryer
Antioxidants
Dissolved oxygen contents in oil
PHYSICAL AND CHEMICAL PARAMETERS OF FRYING OIL
DETERMINATION OF ACIDITY OF FRIYING OIL
WHAT IS THE ACIDITY?
Acidity is a result of hydrolysis of oil from the triglyceride structure.
WHY DOES ACIDITY INCREASE ?
Free fatty acid is an important index for oil quality and shelf life of the oil
Acidity increases as free fatty acids occur from the hydrolysis of oil.
The increase in free fatty acids means that oxidation stability decrease
It is one of the important indicators for that rancidity of oil will start
PROCEDURE OF ACIDITY
Weigh 5 g of oil and transfer it into 300 ml conical flask
Add 50 ml of alcohol -ether solution to the oil solution
At the end of the dissolution add 1 or 2 drops of phenolphthalein indicator.
Titrate this against the 0.1 N KOH solution from the
burette.
The appearance of pink color indicates the end point
CALCULATION OF ACIDITY EXPERIMENT
Vol. of KOH*2.8
Acidity(%oleic acid)=
wt of sample (g)
DETERMINATION OF PEROXIDE IN FRYING OIL
The most common test for the determination of oil oxidation is peroxide value (PV).
It is a parameter representing the extent of oxidation
WHAT IS THE PEROXIDE ?
Peroxide is a compound that formed from triglyceride and not stable.
Oil oxidation is an undesirable series of chemical reactions involving oxygen that degrades the quality of an oil.
WHICH PARAMETERS EFFECT PEROXIDE VALUE?
Temperature
Oxygen exposure
Light
Moisture
Transition metals,
PROCEDURE OF PEROXIDE VALUE
Weigh 3,5 g of oil and transfer it into 250 ml erlenmayer flask
Add 30 ml of chloroform-acetic acid solution to the oil solution
Add 1 ml of KI into solution
Wait 5 min this solution at dark environment
After waiting,add 75 ml of distilled water and 1 ml starch
solution.(If dark color is observed,solution has peroxide)
Titrate this against the 0.002 Na2S2O3solution from the burette
until the red color observed.(brick red)
CALCULATION
V*2.8
Peroxide value =
wt of the sample (g)
V:Consumed 0,002 N Na2S2O3
Color
Color formation in oils during frying is one of the most noticeable degradation reactions that occur in the frying oil.
To control the condition of the natural color of the pigment in the composition of the oil.
To control the bleaching process perform correctly.
COLOR
Different oils darken at different rates
Oils with more natural anti-oxidants will darken more than oils with lower levels of natural anti-oxidants
Protein products caused both the fastest darkening and thermo-oxidative deterioration of the frying oil.
HOW TO COLOR MEASURED?
The HunterLab L*,a*,b* commonly used in the food industry.
The systems measure the degree of lightness (L),
The degree of redness or greenness (+/-a), and
The degree of yellowness or blueness (+/-b).
ACIDITY AND PEROXIDE VALUES ACCORDING TO TSI
CONCLUSION
Acidity increases depending on the frying time which causes the rancidity in oil. Result of the rancidity unpleasant odor and flavour occurs.
Peroxide shows variability depending on the time.
L value of color is different for standards.This may stem from added some sunflower oil during frying process.
EFFECTS ON HEALTH
Reusing oil is that can create free fatty acids, ketones, aldehyde etc. which cause ailments in the long run
This type of frying oil indicate mutagenic and carcinogenic effects which are caused the health problems .
Shallow frying is cooking process in highly heated oil, promoting browning of
battered or non battered foods
Deep Fat frying is a cooking process that involves submerging a food in extremely hot oil in the presence of air at a high temperature of 150°C to 190°C.
Par-frying is a industrial process, food is partially dehydrated in a industrial fryer and flash frozen at -20°C and packaged par-fried food stored at -5°C to -10°C before distribution in freezer trucks
Frying oil plays a great role in quality of the fried product, acts as a heat transfer medium and contributes to texture and flavor of fried food.
Frying oil role in frying
Texture
Fried food flavor
Mouthfeel
Aftertaste
Selection basis
Product flavor
Product texture
Product appearance
Mouthfeel
Aftertaste
Shelf life of the product
Availability of the oil
Cost
Nutritional requirements
To meet current market desire, frying oil must be
Low in saturated fat
Low in linolenic acid
High oxidative and flavor stability
Not hydrogenated (trans-fat free)
Changes during Frying
In Food
Loss of moisture
Development of dark color, firm texture and fried flavor
In Oil
Bland flavor at initial frying, later develops fried food flavor in oil
Changes due to chemical reactions
Dark and viscous
Oil and food both passes through an optimum stage after which quality of oil and product flavordeclines
Unsaturated fatty acids decreases with increasing number or time of frying
Oil and food both undergo severe changes due to frying, difficult to relate every change in differentfrying process, because of the variables of oil, food and process conditions
Understanding new compounds and their dependence on the main variables of the frying process –
Important
Chemical Changes in Oil during Frying
Fresh oil – Fried food appears bland
Reused oil – Fried flavor
New compounds formed in oils during frying process
Foodelphi.com Science of Food Engineering