الفهرس 
Physical delineationOnly 14 pages are availabe for public view
 |  | from | 369 |  |  |
| | | from | 369 | | |
Abstract
The s h e l f - l i f e of milk powders is a main concern f o r the producer and consumer alike. A fresh product having a l l good c h a r a c t e r i s t i c s without an adequate s h e l f - l i f e w i l l shortly unfit human consumption. The work herein contained was forged out to evaluate the s h e l f - l i f e of the 3 concerned powders i n the s e r i e s undertaken to reveal t h e i r functional properties. Changes i n the numerical scores i n conjunction with t h e i r sensory a t t r i b u t e s during various periods of storage were also intended. Search was made for the quantitative determination of alliance magnitude between the s h e l f - l i f e of these powders and its pertinent parameters in these powders when received or when s t a r t e d spoilage. The former was sought for finding a c e r t a i n reproduciple parameter or parameters indicative to the incepient s h e l f - l i f e of these powders when received. The second was sought f o r determining any of these pertinent parameters is accurately expressive i n defining the end point of s h e l f - l i f e as a l a b tool when compared with the subjective sensory evaluation. Attained data on these topics may be summarized as follows: -( 1 ) : Shelf-Life Per iods : Highest average of 5.30 months was that of powder(C).Lowest average of 3.90 months was t h a t of powder (B). Powder (A) had an average of 4.85 months .Though some higher values than those currently attained were encountered i n the l i t e r a t u r e , they were considered reasonable on / the basis of p r a c t i c a l usages. No mention was made f o r a d e f i n i t i v e numerical limit of dried m i l k s s h e l f - l i f e in Egyptian dairy l e g i s l a t i o n . Both t.~pes of dried whole milk showed the same c r i t i c i s m s when began s p o i l . These c r i t i c i s m s were oxid ized flavour, lumpiness, and browning. Dried skim m i l k exerted s t a l e flavour, caking, and browning when s t a r t e d v i t i a t i o n . It was deduced that the remained f a t content i n t h i s powder d i d not implicate i n its flavour defect. (2): Scores and Sensory Attributes during Storage: High average values were obtained for the t o t a l score of 3 powders when received. The 3 averages did not extensively v a r i a t e . The packages of (B) and (C) powders were scored a t lower points a t that time of evaluation for t h e i r poor quality. The EOS (1988) is the only local standard defining some requirements for the sensory a t t r i b u t e s and packages of dried milks. A gradual continuous decrease occurred i n the scores of various considered items f o r the 3 powders by the extension of storage. Powder (A) and (B) almost behaved the same career i n t h e i r deterioration. I n both types, oxid ized flavour began with the appearance of f l a t flavour. With prolonging storage t h i s flavour was transformed into tallowy flavour. Brownine and lumpiness were i n t e n s i f i e d with progressive storage. Rust signs appeared i n the t i n cans of powder (A ) while the Al-saoks remained undef ec t i v e t i l l the termination of storage but a t a l e s s e r degree of brightness- Caking was more prominent than s t a l e flavour and browning i n a l l spoiled powder (C) samples. (3): Alliance Between Shelf-Life and Pertinent Parameters a t Storage S t a r t : Weak r e l a t i o n s between s h e l f - l i f e and most pertinent parameters were attained on the receipt of the 3 powder types. The most consistent r e l a t i o n was that of moisture content. This highly distinct r e l a t i o n appeared i n the 3 powders a1ike.Thj.s revealed a high r e l i a b i l i t y to t h i s parameter as an i n f e r a b l e i n d i c a t o r f o r t h e i r incipient shelf-life. An obvious alliance was also exerted by the free f a t content i n dried whole milks but a t a l e s s e r degree than moisture- Browning t of a1 i n t e n s i t y also exhibited a considerable degree of a l l i a n c e i n both types of whole powders. PRC showed a f a i r l y tangible t i e in a l l tested powders,being s l i g h t l y l e s s e r i n powder (B). (4): Alliance Between Shelf -Lif e and Pertinent Parameters a t . Spoil S t a r t : Contrary t o storage s t a r t , a t spoil s t a r t strong r e l a t i o n s between s h e l f - l i f e and most of the same checked pertinent parameters in the 3 powder types were revealed. The development of d e t e r i o r a t i v e changes i n these powders by prolonged storage was the causative agent f o r such strqng r e l a t i o n s . This s i g n i f i e s that t h e d e t e r - i o r a t i o n of the 3 powders was not r e s t r i c t e d t o the 3 critisms detected i n every of them,bn& extended to most other parameters.