FACTORS AFFECTING THE PHYSICAL AND NUTRIENT COMPOSITION OF DRIED CITRUS PULP

Transcription

1 AMMERMAN ET AL: DRIED CITRUS PULP I UJ i are subject to surface browning if epidermal tis sue is injured and they are exposed to brief periods when the evaporation rate is high. On a very dry, hot day potatoes may be injured by exposure for as little as minutes. In gen eral it takes at least hours to initiate brown ing. Dry conditions are most prevalent between 0 A.M. and P.M. during which time growers, particularly those not harvesting in bulk, should provide immediate protection to skinned tubers. During extremely dry conditions growers might curtail harvesting until more favorable condi tions exist. o a: LJ 0 AM 0 I TIME OF DAY PM Fig:.. Mean percent relative humidity and range during daylight hours at Jacksonville, Florida. May. It is therefore concluded that freshly dug Florida potatoes, both red and white varieties, LITERATURE CITED. Artschwager, Ernst.. Wound periderm forma tion in the potato as affected by temperature and humidity. Jour. Agr. Research () : Barger, W. R., G. B. Ramsey, R. L. Perry and J. H. MacGillivary.. Handling and shipping tests with new potatoes from Kern county, California. Calif. Agr Expt. Sta. Bui... Benn, Harold W.. Harvesting and shipping early potatoes. Amer. Potato Jour. :.. Ramsey, G. B., L. M. Lutz, H. O. Werner and A. D. Edgar.. Experiments on shipping washed early potatoes. Nebr. Agr. Expt. Sta. Bui... Rose, D. H. and D. F. Fisher. 0. Desiccation effects on skinned potatos. Amer. Potato Jour. :.,. Handling and shipping early po tatoes. U.S.D.A. Circular No.. FACTORS AFFECTING THE PHYSICAL AND NUTRIENT COMPOSITION OF DRIED CITRUS PULP C. B. Ammerman, J. F. Easley, L. R. Arrington and F. G. Martin Dried citrus pulp has been shown by both research (,,,, and ) and practical feed ing to be a valuable feedstuff for ruminants. Specific processing procedures vary from one production source to another and may vary with in the same source throughout the season. The basic procedure consists of grinding or chopping and then dehydrating the fruit residue. The fruit residue is either dehydrated as such, or it is pressed and molasses is produced from the press liquor. A portion of the molasses is some times added back to the pulp in the drying pro cess. The finer particles of the dried pulp are often removed and either sold as citrus meal or pelleted and added back to the pulp. These and other differences in processing, in source and variety of fruit, and in type of canning opera tion from which the fruit residue is obtained, may result in variations in the nutrient content of dried citrus pulp. The objectives of this study were to deter mine: () physical characteristics of dried citrus pulp, () nutrient content and the contribution of the various physical fractions to the total nutrient composition of pulp, and () variability in the nutrient composition of citrus pulp mar keted within the state. Florida Agricultural Experiment Stations Journal Ser ies Number. idepartment of Animal Science. Florida Agricultural Experiment Station, Gainesville. Experimental Procedure Twentyfour, 00pound samples of dried citrus pulp representing thirteen production

2 FLORIDA STATE HORTICULTURAL SOCIETY, sources were obtained during midseason (Janu ary and February) for the determination of physical and nutrient composition. The density of each sample was determined, as received, by three weighings using a one cubic foot box. The container was filled by allowing the pulp to flow freely with no vibration of the container. Two, 00gram samples of each citrus pulp were sep arated into two fractions using a U.S. Bureau of Standards Number 0 Sieve. The fraction re tained on the sieve was separated further into pellets or visually detectable seed or seed parti cles with the remainder considered to be pri marily peel plus pulp. The seed fraction was separated further on the basis of broken or in tact seeds. The weight of each fraction was ob tained and with the intact and broken seeds recombined, the four fractions were ground and prepared for chemical analysis A second study was conducted to ascertain the variability in the nutrient composition of dried citrus pulp marketed within the state. The proximate analyses of samples of citrus pulp obtained by the Feed Laboratory, Division of Chemistry, Florida Department of Agricul ture, were summarized. These samples included samples collected during, 0 during, and 0 during. To make compari sons in nutrient composition of pulp between production sources, the analysis for 0 samples representing production sources were suitable for use. Chemical analyses for moisture, ash, protein, ether, and crude fiber on all samples were conducted according to AOAC (). Cal cium and magnesium were determined with an atomic absorption spectrophotometer using methods outlined by Parker (). The data were subjected to analysis of variance with significant differences between means determined by the multiple range test of Duncan (). Results and Discussion The physical characteristics of twentyfour samples of dried citrus pulp collected in midseason are shown in table. density for all samples was.0 pounds per cubic foot with a range of. to. pounds in dicating wide differences in density. The pres ence of pelleted material did not appear to influ ence greatly the density of the citrus pulp. The material which would pass a No. 0 sieve (minus 0 mesh fraction) was considered to include both fines and pellets since the pellets represent ed the fine particles initially sifted from the pulp, pelleted, and then added back. Consider ing all samples, the fines represented 0.% and the pellets.% for an average of.% of the original citrus pulp which would have passed a 0 mesh screen. Variability in the quantity of the total minus 0 mesh fraction is illustrated by the range of. to.0%. As shown in table, only eight of the twentyfour samples contained pellets. These samples con tained an average of.% pellets with.0 to.% of the total citrus pulp represented by pellets. The material retained on a No. 0 sieve (plus 0 mesh fraction) included peel plus pulp and seeds, and represented an average of.% of the total sample. The range in this fraction was.0 to.%. Seeds represented.% of the total sample with.% being intact seeds. Several factors may have contributed to the differences observed in density and physical composition. The type and degree of chopping or grinding prior to dehydrating influences par ticle size of the resulting dried pulp. Also, the finer particles are sometimes screened from the dried pulp and sold separately as citrus meal. Thus, coarser grinding of the wet pulp and re moval of citrus meal would decrease the density of the pulp and result in less of the "minus 0 mesh fraction." The amount of seeds present in the sample would depend in part on variety of fruit and on the type of canning operation providing the wet fruit residue. The average nutrient composition of the component fractions of citrus pulp is shown in table. Seeds were considerably higher in pro tein and ether and lower in ash, crude fiber, and nitrogenfree than the other fractions. The remaining fractions including peel plus pulp, fines, and pellets were rather similar in nutrient composition. All fractions differed significantly (P <.0) in ash content with pel lets containing the highest level,.%, and seeds the lowest,.%. Fines and pellets were significantly higher in calcium and phosphorus and were numerically higher in ether and protein than was the peel plus pulp frac tion. These data suggest that more of the in organic matter remained with the finer particles and also that the fines and pellets may have contained small broken particles of seeds as evidenced by the slightly higher protein and

3 _ AMMERMAN ET AL: DRIED CITRUS PULP TABLE. PHYSICAL CHARACTERISTICS OF DRIED CITRUS PULP Number of Samples Characteristic Range Density (Samples with pellets), lb/cu ft.0.. Density (Samples without pellets), lb/cu ft... Density (All samples), lb/cu ft.0.. Fines (Samples with pellets), %.0..0 Fines (Samples without pellets), %...0 Fines (All samples), % Pellets (Samples with pellets), %..0. Pellets (All samples), %. TOTAL...0 Peel plus Pulp (Samples with pellets), %. Peel plus Pulp (Samples without pellets), %. Peel plus Pulp (All samples), % Seeds (All samples), %... TOTAL..0. Seed Condition Whole (All samples), % Broken (All samples), %..0. *A values obtained on citrus pulp samples under airdry conditions. Twentyfour samples of pulp examined with only eight containing pellets. Dried citrus pulp separated using U.S. Bureau of Standards No. 0 Sieve. Although pellets were retained, they were considered as part of the minus 0 mesh fraction. TABLE. AVERAGE PERCENT NUTRIENT COMPOSITION ON A DRY MATTER BASIS OF DRIED CITRUS PULP FRACTIONS " Nutrient Proximate Composition, % ~~Mineral Composition,.. Nitrogen Citrus pulp Ether n Crude free Magfraction Ash Protein fiber Calcium Phosphorus nesium Minus 0 Mesh Fines.b. b.b.a.a.a 0. Ubc 0. b Pellets.a. b.b.a.a.a 0. b 0. b Plus 0 Mesh Peel plus Pulp.0c.b.0b a.. a. b 0. 0c 0. b Seeds.d.a.a. 0b. 0b 0. C 0. 0a 0. a XA values based on twentyfour samples except those for pellets. Only eight of the twentyfour samples contained pellets. Means in the same column with different superscripts are significantly (P<.0) different. Kjeldahl nitrogen x.. Samples separated using U.S. Bureau of Standards No. 0 Sieve. Although pellets were retained, they were considered as part of the minus 0 mesh fraction.

4 FLORIDA STATE HORTICULTURAL SOCIETY, ether. With total removal of the seed fraction, the peel plus pulp contained.0% pro tein on a dry matter basis while the fines and pellets contained.% and.%, respectively. The seeds in this study contained higher levels of protein, ether, and nitrogenfree ex tract and lower levels of ash and crude fiber than reported previously by Ammerman, et al. () for whole citrus seeds. This can be explain ed by the many broken seed kernels included in the present samples without the corresponding seed hull. The percentage of total nutrients contributed by each fraction of citrus pulp was calculated and recorded in table. These values were cal culated from physical composition (table ) and nutrient composition of each physical fraction (table ). Except for seeds with their higher protein, ether, magnesium, and phos phorus content, the average contribution of each fraction to the total nutrient composition of the citrus pulp tended to be about the same as that fraction's average representation on a quantita tive basis. Thus for ash, crude fiber, nitrogenfree and calcium, about 0% of the nu trients came from peel plus pulp, 0% from fines, and % from pellets. The seeds contribu ted approximately % of the ether and % of both the protein and phosphorus present in the total pulp, but contributed relatively little of the ash, crude fiber, and nitrogenfree fractions. The contribution of seeds to the total composition of citrus pulp is shown further by the observation that for each % increment of seed substitution for peel plus pulp (table ), ether will be increased by about 0.% and protein by 0.0%. The content of ash and crude fiber will remain essentially unchanged while nitrogenfree will decrease in amounts comparable to the combined increases in ether and protein. These values were calculated assuming 0% dry matter in the feed stuff and using the data for peel plus pulp shown in table, which were considered to re flect very limited amounts of seeds. The nutri ent composition data for whole citrus seeds ob tained by Ammerman, et al. () were used. The average nutrient composition of cit rus pulp samples analyzed by the Feed Labora tory, Florida Department of Agriculture, for a threeyear period is shown in table. The mois ture content of the pulp as collected varied from. to.% with an average of.%. The ranges in nutrient composition listed for the airdry samples suggested considerable variation in nutrient content. Expressed on a dry matter TABLE. AVERAGE PERCENT NUTRIENT CONTRIBUTION FROM EACH CITRUS PULP FRACTION TO THE TOTAL NUTRIENT COMPOSITION OF THE PULP Percent of Nutrients Contributed Citrus pulp fraction Ash Ether Protein Crude fiber Nitrogenfree Calcium Phosphorus Mag nesium Minus 0 Mesh Fines Pellets TOTAL Plus 0 Mesh Peel plus Pulp Seeds TOTAL ^All values based on twentyfour samples except those for pellets. Only eight of the twentyfour samples contained pellets. Kjeldahl nitrogen x.. Samples separated using U.S. Bureau of Standards No. 0 Sieve. Although pellets were retained, they were considered as part of the minus 0 mesh fraction.

5 AMMERMAN ET AL: DRIED CITRUS PULP basis, the average nutrient composition for all samples was as follows: ash,.; ether,.; protein,.; crude fiber,.; and nitrogenfree, 0.%. The average nu trient composition of dried citrus pulp varied only slightly from year to year (table ). The average nutrient composition of the cit rus pulp samples according to production source is shown in table. Significant (P <.0) dif ferences were found between production sources for all nutrients. The average ether content by production source varied from. to.%, and the standard deviation within production source was ±.%. Protein content varied also according to source and was highly correlated (r = 0.) with the content of ether when the average values for the seven teen production sources were compared. The level of crude fiber and level of nitrogenfree were shown to be inversely correlated (r = 0.). Citrus pulp from source number had a crude fiber content of.% and a nitrogenfree content of.% while the pulp from source number contained only.% crude fiber and.% nitrogenfree ex tract. Most of the pulp samples containing high levels of crude fiber and low levels of nitrogenfree were from production sources known to be producing molasses. A portion of the mo lasses, however, may have been added back to the pulp in the drying process. Summary Samples of dried citrus pulp were examined to determine their physical and chemical compo sition. Twentyfour samples, from thirteen pro duction sources were examined to determine den sity and physical composition. The samples were separated into two fractions using a U.S. Bu reau of Standards Number 0 Sieve. The frac tion retained on the sieve was separated further into pellets, visually detectable seeds or seed par ticles, and peel plus pulp Considering all twentyfour samples, an average of 0.% pass ed the sieve, and.% was retained. The latter fraction, when expressed on the basis of the whole sample, consisted of seeds,.%; pellets,.%; and peel plus pulp,.%. Only eight of the twentyfour pulp samples contained pel lets with an average pellet content of.0% by weight. In another study, analyses of sam ples of dried citrus pulp obtained by the Feed Laboratory, Division of Chemistry, Florida De partment of Agriculture, were summarized. These samples were collected during,, and. The average moisture content for all samples was.% and, exposed on a dry TABLE. AVERAGE NUTRIENT COMPOSITION OF CITRUS PULP SAMPLES COLLECTED OVER A THREEYEAR PERIOD Nutrients % Year Number of Samples Moisture Ash Ether Protein Crude fiber Nitrogenfree Air dry basis Range !..0. Dry matter basis : Combined Kjeldahl nitrogen x..

6 FLORIDA STATE HORTICULTURAL SOCIETY, TABLE. AVERAGE NUTRIENT COMPOSITION OF CITRUS PULP SAMPLES COLLECTED OVER A THREEYEAR.PERIOD EXPRESSED IN PERCENT ACCORDING TO PRODUCTION SOURCE Moisture Ash Ether Source Level o Protein^ Crude Source fiber Level Nitrogenfree *..... T Std., Dev.~ Twelve to samples represented by each production source for a total of 0 samples. All values except moisture expressed on a dry matter basis. All values in the same column not covered by the same line are significantly (P<.0) different. Kjeldahl nitrogen x.. Within production source standard deviation. matter basis, the average proximate composition was as follows: ash,.%; protein,.%; ether,.%; crude fiber,.%; and nitrogenfree, 0.%. Significant (P <.0) dif ferences in the nutrient composition of the dried citrus pulp samples were found between produc tion sources. Acknowledgements The authors wish to acknowledge the Florida Citrus Processors Association in cooperation with the Florida Citrus Commission for funds in support of this study; Mrs. Mary Maud Sharpe, Chief, and Mr. Harold Hoffman, former Chief, Feed Laboratory, Division of Chemistry, Florida Department of Agriculture for analyti cal data of citrus pulp samples analyzed during,, and ; and M. C. Jayaswal and Barbara King for technical assistance. LITERATURE CITED. Ammerman, C. B., P. E. Loggins, and L. R. Ar rington.. Comparative feeding value of dried citrus pulp and ground snapped corn for fattening lambs. Ani mal Science Mimeo. Series No., Fla. Agr. Exp. Sta., Gainesville.. Ammerman, C. B., P. A. van Walleghem, J. F. Easley, L. R. Arrington, and R. L. Shirley.. Dried citrus seeds Nutrient composition and nutritive value of protein. Proc. Fla. State Hort. Soc. :.. Ammerman, C. B., P. A. van Walleghem, A. Z. Palmer, J. W. Carpenter, J. F. Hentges, and L. R. Arrington.. Comparative feeding value of dried citrus pulp and ground corn and cob meal for fattening steers. Animal Science Mimeo. Series No. AN, Fla. Agr. Exp. Sta., Gainesville.. Association of Official Agricultural Chemists. Official Methods of Analysis. th Ed. Washington, D. C 0.. Becker, R. B. and P. T. Dix Arnold.. Citrus pulp in dairy rations. Fla. Agr. Exp. Sta. Cir. S0.. Duncan, D. B.. Multiple range and multiple F tests. Biometrics :.. Kirk, W. G. and G. K. Davis.. Citrus products for beef cattle. Fla. Agr. Exp. Sta. Bui... Parker, H. E.. Magnesium, calcium, and zinc in animal nutrition. PerkinElmer Atomic Absorption Newsletter. :.. Peacock, F. M. and W. G. Kirk.. Comparative feeding value of citrus pulp, corn feed meal and ground snapped corn for fattening steers in dry lot. Fla. Agr. Exp. Sta. Bui..