Presented by :Subhendu Panigrahi

05AG3303Under the guidance of :

Prof . H.N.Mishra

1.IntroductionFood Quality is a subjective and intuitive concept

– becoming increasingly important nowadays.Perception of quality differs from person to person.

Quality important in determining repeat purchases.

Food Quality- A dynamic phenomenon

Quality changes during its movement from farm to fork.

Change agents are physical, chemical or biological.

Studies show that temperature is the predominant factor in quality change.

Shelf-life No uniform and applicable definition .Finite length of time after productions for

which it will retain a required level of organoleptic and safety qualities under stated conditions of storage.

Depends on specific commodities .Depends on definition’s intended use (i.e., for

regulatory or for marketing purposes.

Objective(s)

To quantify color change of frozen beans during distribution in chilled chain

To develop mathematical relation between color change and time

Frozen FoodsShelf life of fresh food products can be

increased by super chilling (partial freezing). Partial freezing in industry can reduce the

use of freezing/thawing by producing high thermal buffers of partially frozen foods and thereby reducing labor, energy costs and product weight losses.

The ice stored in super chilled products will protect from temperature abuses during transportation and storage.

Process Flow for Quality modeling

Modelling approachFood quality change correlated to

composition and environmental factors .Quality assumed to be numerically related to

a quantity A, a function of time t and of spatial position x.

Quality change is governed by a mathematical model of general form

dA/ dt = (A, v1, v2, v3 , ... vm, P)

Where change agents are v1, v2, v3 , ... vm

The solution of differential equation can be written as

A (t)/Ao = 1- Ao-1 Φ (t) for n = 0 (zero

order reaction)

= exp{- Φ (t) } for n = 1 (first order reaction)Where Φ(t) =

k = k1

k = k1

Product Centric Approach of determining shelf lifeA mathematical argument can be given to

determine shelf life depending on the attributes of the food

Sensory propertiesChemical composition and physical propertiesMicrobiological contaminantsToxicological contaminantsPackaging and labellingThe relative importance of each category depends

upon the food product

Shelf life based on different attributes is important considering the acceptability of the food item at the consumer end.

Depends on the attributes and their scores.Threshold quality or minimum quality of a

quality parameter Ai that is acceptable at the consumer end be Aim and the time elapsed to reach this quality level be tm.

So Aim = Ai(tm)

Fraction of quality remaining at time t, Ri (t) = A( t) - Ai(tm)/ A - Ai(tm)

Shelf life of attribute i Li = Ri (t) / k[T(t)]

Effective Shelf Life, Leff = Weighted Average of all shelf lives

Lmin ≤ Leff ≤ Lmax .

Why color?Color is an important food quality attribute,

which is one of the major decision variables while interacting with consumer.

A consumer makes decision on the visual appearance of the food products.

Moreover the color of the food also affects the taste perception.

Why Texture?Texture can be defined as the properties of

food determined by rheological and structural nature of the food and tactile senses.

The texture of frozen and thawed vegetables will not be comparable with that of material before freezing.

Texture has a major effect on taste perception apart from color.

Why Ascorbic AcidAscorbic acid an, important nutrient present

in vegetables.Studies show degradation follows first order

kinetics.Hence would effect consumption in a quality

conscious market.

Methodology Raw Material Procurement Beans procured from local market , washed and cleaned A part of the beans were blanched in water at 80 degree C for 2

minutes. Storage: Cleaned beans and blanched were initially stored at -10, -5 and 4

degree C for different times. Color Measurement L, a , b values measured by CR-Minolta Chromameter Texture Measurement Hardness values were obtained from the Force-Time curve

measured in Stable Micro Systems TAXT2-i Texture Analyser. Juiciness was also measured by pressing the frozen beans between two filter papers.

Ascorbic Acid ContentThe chemical method of estimation was applied

to estimate the content of Ascorbic acid based on the reduction of 2, 6-dichlorophenol indophenols by ascorbic acid.

Data Analysis Values of the different measured indices

were plotted vs. time for all temperature studied and the apparent order of quality loss was

ResultsSamples stored at −10oC , and 10oC and

thawed at 4°C developed color change from lighter green to darker one hours of storage with L decreasing over time.

The color change may have occurred due to enzymatic reactions of chlorophyll.

Changes of b-value has high with, Ea = 135 kJ/mol values.

Fig 2 indicates strong dependence on storage temperature

Figures

Figure 2 Effect of temperature on reaction constant of frozen beans

TextureRaw beans had the highest hardness value.Blanching lowered the hardness values considerably i.e.

46% reduction.Freezing had a considerable effect on texture of the beans. Results show both time and temperatures are responsible

for the inferior quality of texture in frozen beans. May have occurred due to mechanical damage in tissues.

Thawing at 4oC had the lowest hardness values i.e. 792.7 gJuiciness increased as the frozen storage times increased.

Ascorbic Acid ContentThe visual titration method showed that the ascorbic

acid content of raw beans was 21.5 mg/100gm of beans. Ascorbic acid degradation was highly dependent on

time-temperature history of the product and also the pre-freezing methods applied

The blanched one had low ascorbic acid content with 3.225 mg/100gm of beans and the unblanched had 9.675 mg/100 gm of beans stored at same time-temperature conditions.

Changes of AA content was found having high value , Ea = 504.1 kJ/mol values, at reference temperature, Tref = -18oC for frozen foods,

Fig 3. Effect of temperature on k- values for AA degradation

DiscussionThe aim of the present study was to establish and validate

reliable kinetic models of color, ascorbic acid content and texture , as the quality indices for frozen beans during frozen storage and distribution that would allow estimation of the quality of frozen beans during non-isothermal handling of products, in the real distribution in a chilled chain .

All the indices showed dependence on temperature and time.

Ascorbic acid could be limiting parameter at lower temperatures.

A Temperature data from recent surveysA survey was conducted by Laboratory of Food

Chemistry and Technology, National Technical University of Athens in collaboration with a leading supermarket chain illustrated in Fig. 3

The retail supermarkets have no fixed range of display and storage temperature.

This leads to more thermal abuse of the product.

Figure 4: Average storage temperatures measured in different types of retail freezers in several stores of a large supermarket chain

Future WorkFind out the traits important for consumers

while buying beans by Hedonic Price Analysis.

Develop an ERP or platform to find out the shelf-life of beans.

Apply the principles of Quality Index Method (QIM) which is considered the ideal tool for the determination of fish freshness in the project EuroFish to beans.

Thank You