Studies on Reversible Compression of Dehydrated Vegetables

Rahman, Abdul R; Schafer, Glenn; Taylor, George T.; Westcott, Donald E

doi:10.21236/ad0698457

Cited by 5 publications

(3 citation statements)

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“…Very little work has been done on the effect of compression on the physical characteristics and cell structure of plant products. Rahman et al (1969) indicated that freeze-dried spinach, carrots, and green beans compressed under 500-2000 psi show no significant difference from their uncompressed counterpart upon rehydration.…”

Section: Introduction Freeze-driedmentioning

confidence: 99%

Histological and Physical Changes in Carrots as Affected by Blanching, Cooking, Freezing, Freeze Drying and Compression

Rahman

Henning

Westcott

1971

Journal of Food Science

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SUMMARY— The effect of processing variables on the cell structure and physical characteristics of carrots were determined. The phloem portion of fresh carrots was subjected to one of the following treatments: blanching; cooking for 10 min; freezing at 0°F, −30°F or −320°F; freeze drying, compressing after freeze drying at approximately 1500 psi. Carrots at each treatment were tested for: (1) texture by means of the Ailo‐Kramer Shear Press; (2) water holding capacity by centrifuging at 500, 1000, 1500, 2000 and 2500 rpm; (3) histological changes by microscope observation of the tissue structure. Results indicate that among all treatments, freezing temperature is the most critical factor affecting the cell structure of the carrots. Freezing at 0°F or −30°F results in considerable disruption of the cellular structure, whereas it was minimal at −320°F. Carrots frozen at −320°F showed firmer texture as well as higher water holding capacity than the rest. Significant correlation coefficient was established between the shear press values and percent weight loss measured by centrifugation. This suggests that the latter may be used as an objective test for measuring textural changes in processed carrots and perhaps other foods.

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Section: Introduction Freeze-driedmentioning

confidence: 99%

Histological and Physical Changes in Carrots as Affected by Blanching, Cooking, Freezing, Freeze Drying and Compression

Rahman

Henning

Westcott

1971

Journal of Food Science

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“…Bulk density was measured by dividing the weight of the loose or compressed product by its respective volume. The compression ratio was determined by dividing the bulk density of the compressed product by that of the uncompressed product (Rahman et al, 1969).…”

Section: B Compressionmentioning

confidence: 99%

Reversible Compression of Dehydrated Peas

Rahman

Bishov

Westcott

1971

Journal of Texture Studies

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Freeze-dried peas were compressed 4-fold and subsequently rehydrated to virtually their precompression characteristics. Histological studies showed that conventional processes of freezing and freeze-drying result in considerable disruption of cell walls. Contrary to what was anticipated, compression forces of 1000-2000 psi resulted in only a slight increase in breakage of cell walls. However, no correlation was established between cell disruption or texture and increasing compression force. A study of the effects of plasticizing moisture and compression force enabled optimization of processing conditions resulting in compressed peas which can be reconstituted to virtually their precompression characteristics.

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“…Brockmann (1966) reported that freeze-dried foods properly preconditioned can be compr essed with little or no fragmentation and that most foods so compressed can be restored t o th~ir precompression characteristics. Rahman, et al (1969) reported that freeze -dried peas, corn, sliced onions, spinach, carrots, and green beans were successfully compressed, and compression ratios of 4: 1 , 4 :1 , 5:1, 11:1, 14:1 1 ~~d 16:1 wer e obtained respectively. Compressed discs approximately 3-3/4 inch diameter have been developed f rom freeze -dried bl ueberries and red t a rt pitted (RTP) cherries.…”

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confidence: 99%