Objectives: The aim of this study was to assess the bioaccessibility of iron and zinc in African leafy vegetables (ALV) and maize porridge composite dishes using an in vitro dialysability assay and to estimate the antinutrient content in ALV and maize porridge composite dishes. Methods: ALV leaves were collected, cooked and mixed with either cooked fortified or unfortified maize porridge to simulate the way it is usually consumed. Mineral and antinutrient levels were determined using standard methods and the bioaccessibility of iron and zinc was determined using an in vitro dialysability assay. Findings: The findings of the present study indicated that ALV dishes contain a reasonable amount of iron and zinc, but combining the ALV dishes with unfortified maize porridge resulted in dilution and hence a lower iron content. The amaranth-pumpkin dish contained most iron (24 mg/100 g). ALV dishes in the study had zinc contents ranging from 2.6 to 3.2 mg/100 g, with amaranth mixed with spider plant having the highest zinc content. Regarding antinutrients, the amaranth-cowpea dish had the highest phytate content of 2078 mg/100 g dry weight. ALV dishes also contained tannins and phenolic compounds. Iron percentage bioaccessibility was high in an amaranth-spider plant dish (25%), while other dishes had lower iron bioaccessibility of less than 11%. The percentage bioaccessibility of zinc in ALV dishes ranged from 7 to 8%. The amaranth-spider plant dish had higher zinc bioaccessibility when composited with fortified maize meal (13%). The percentage zinc bioaccessibility is negatively associated with phytate:zinc and phyate-calcium:zinc molar ratios. Conclusions: ALV and maize meal composite dishes have a high iron and zinc content, though they also have a high antinutrient content that has some inhibitory effects. Despite the inhibiting factors, the amount of bioaccessible iron and zinc from ALV and maize porridge composite dishes could play a significant role in planning food security strategies. However, there is a need to understand the possible effects of consuming them in different combinations with other foods. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2015

Objectives: The aim of this study was to assess the bioaccessibility of iron and zinc in African leafy vegetables (ALV) and maize porridge composite dishes using an in vitro dialysability assay and to estimate the antinutrient content in ALV and maize porridge composite dishes. Methods: ALV leaves were collected, cooked and mixed with either cooked fortified or unfortified maize porridge to simulate the way it is usually consumed. Mineral and antinutrient levels were determined using standard methods and the bioaccessibility of iron and zinc was determined using an in vitro dialysability assay. Findings: The findings of the present study indicated that ALV dishes contain a reasonable amount of iron and zinc, but combining the ALV dishes with unfortified maize porridge resulted in dilution and hence a lower iron content. The amaranth-pumpkin dish contained most iron (24 mg/100 g). ALV dishes in the study had zinc contents ranging from 2.6 to 3.2 mg/100 g, with amaranth mixed with spider plant having the highest zinc content. Regarding antinutrients, the amaranth-cowpea dish had the highest phytate content of 2078 mg/100 g dry weight. ALV dishes also contained tannins and phenolic compounds. Iron percentage bioaccessibility was high in an amaranth-spider plant dish (25%), while other dishes had lower iron bioaccessibility of less than 11%. The percentage bioaccessibility of zinc in ALV dishes ranged from 7 to 8%. The amaranth-spider plant dish had higher zinc bioaccessibility when composited with fortified maize meal (13%). The percentage zinc bioaccessibility is negatively associated with phytate:zinc and phyate-calcium:zinc molar ratios. Conclusions: ALV and maize meal composite dishes have a high iron and zinc content, though they also have a high antinutrient content that has some inhibitory effects. Despite the inhibiting factors, the amount of bioaccessible iron and zinc from ALV and maize porridge composite dishes could play a significant role in planning food security strategies. However, there is a need to understand the possible effects of consuming them in different combinations with other foods. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2015

Since vegetables are of such importance in the nutrition of human beings, it is natural that they should play a large part in Army feeding. They are high in food value. The different kinds vary widely in their energy values; some-- like potatoes--are high in carbohydrates, others--like lettuce and cucumbers-- are low. Fresh or canned they are high in minerals and vitamins, low in protein and fat, and are valuable for bulk and palatability. When purchasing fresh produce it was necessary to know something of quality, appearance, and texture. Quality is made up of many characteristics-- some external, internal, chemical, and physical. Appearance is concerned with shape, color, freedom from blemishes and dirt. Texture contrasts hard or soft, smooth or granular, stringy and fibrous or free from fiber, crisp or flabby, wilted or tough. The flavor of vegetables is due to several constituents: sugar, organic acids, mineral salts, and aromatic compounds. A combination of these gives flavors that make vegetables palatable and attractive. The nutritive value of a given vegetable depends on the part of the plant to be used, as well, as the variety, climate, soil in which it is grown, conditions of storage, and preparation. The leaf, stem, flower, seed, and fruit are all edible parts. When purchasing vegetables for the Army it was well to know that the initial price was by no means the ultimate cost as there was a wide margin between the cost as purchased and edible-portion cost. Waste in preparation, storage, and losses in the cooking of highly perishable produce would cost six cents per pound as purchased and thirty cents per pound edible portion. The condition of the vegetables when delivered has a great influence on the probable yield. When purchasing canned vegetables, grades were used as purchasing guides. Samples of each grade of produce were requested for testing to find out if the product was satisfactory. The highest grade was not purchased for general use; Grade B or Standard was acceptable for the Army mess. Fresh and frozen vegetables were used largely in Army camps and fields in the United States. Canned and dehydrated products were to be used in combat areas overseas because they were easy to prepare, there was little or no waste, and the nutritive value was fairly well retained. The problem of storage was not difficult, and shipping space was saved when dehydrated food was shipped because of its lightness and lack of bulk. The Army food purchasing officer needed to be familiar with the local vegetable supply and market center facilities. A knowledge of standardizing, grading, packaging, sorting, and transporting produce was necessary in order to purchase food economically and intelligently. Because of uncertainty of crops due to curtailed planting and harvesting occasioned by labor shortages, it was difficult for producers and distributors to cooperate at all times. The Quartermaster's office arranged with local marketing centers for information on prices, substitutions, and quantities of local produce available, several days in advance, so that suitable substitutions could be made on menus if sufficient fresh vegetables were not obtainable. Inspection of all food on delivery was required, and if low grade or unsatisfactory produce was discovered it was returned to the dealers or an adjustment requested. This was done to determine whether or not supplies met the contract requirements for quality and conditions specified by the Army. / Graduation date: 1947

This investigation was concerned with the reduction of waste in raw vegetables and fruits between the times of harvest and consumption. Reduction of spoilage in produce was attempted by means of chemical and. physical agents as well as a combination of both. The first phase of the work consisted of an evaluation of a number of chemical compounds with respect to their effectiveness in reducing post-harvest spoilage. The second part dealt with an evaluation of several transparent films applied to raw produce as wrappers and their effect on the keeping quality of the plant material until consumed. Finally combinations of surface disinfection and overwrapping were evaluated for effectiveness against raw produce spoilage. 1. Disinfection Approximately 26 compounds were tested as aqueous dips using 3 concentrations of each on 7 major vegetables and 2 fruits. The following types of compounds were studied. 1. Quaternary ammonium compounds (chlorides, bromides and pyridinium derivatives) 2. Chlorine liberators (organic and inorganic) 3. Phenols (simple and poly-phenols) 4. Quinones and hydroquinones 5. Salts of fatty acids 6. SO₂ liberators 7. Benzoates The chemical treatments were evaluated for each produce by comparison with untreated controls using duplicate tests with triplicate samples for each chemical and concentration. Promising treatments were found for all but one produce (strawberries). The treatments showing promise for each of Pascal celery and Emperor grapes were further tested on a larger scale uaing commercial size units of produce as test samples and long term cold storage. Three chemical treatments for each product were judged satisfactory enough to warrant further testing by means of field trials. The chemicals found most promising for celery were Onyxide, Cetab and Decco while Roccal, Dowicide C and Phygon were selected for grapes. A field test of the three above mentioned treatments for Pascal celery was completed. One thousand bunches per chemical were tested under commercial conditions of dipping and storing. An equal number of untreated bunches was also tested. Half-lots of each treatment were evaluated on each bunch for 11 subjective characteristics and standard mold and bacterial counts of each crate of celery were made after 8 and 14 weeks of storage. On the basis of a statistical analysis of the results, 0.1% Decco of pH=5 can be recommended for the reduction of general rot development in cold storage Pascal celery. Onyxide and Cetab significantly reduce the development of mold but commercial application cannot be recommended because the amount of visible stalk injury was significantly increased over that shown by corresponding untreated or Decco treated celery. 2. Prepackaging The following films were compared for their merit in prolonging the salable life of raw produce. Pliofilm 75FF, Pliofilm 75N2, Pliofilm 75P6A, Cellophane 300LSAT, Cellophane 300MSAT-86, Lumarith P-912, Dupont Acetate 100CA48, Polythene and Kodapak II-130. Wrapping techniques were also evaluated using the followng variations; Complete seals, tent-flap closures, single hole punctures, multiple punctures and windo bags. The following products were studied: celery, tomatoes, carrots, lettuce, cauliflower, chopped salad mix, spinach, strawberries, raspberries, blackberries, and boysenberries. Harvested produce was packaged both before and after the removal of field heat. Behavior of the pre-packaged products in both 33°F storage and subsequent 8O°F storage was studied. Cold storage was extended as long as 120 days while subsequent holding at room temperature varied widely from produce to produce. Observations were made at regular intervals for each product. Several hundred uniform samples were evaluated for most products using duplicates of each treatment for every observation period. Evaluation of most samples included weightloss, C0₂ (and sometimes O₂) of the container atmosphere, mold and decay development, flavor, color, odor, wilting and shriveling. The following conclusions were drawn: All films and wrapping methods affect produce quality. For each produce, treatments could be singled out which were superior to unwrapped controls. However any particular film and type of seal found to be superior for one produce was often not acceptable for another fruit or vegetable. Among the factors found to be critical for the proper choice of treatment were type of produce, produce temperature when packed, length of storage, and temperature of storage. A. Cold Storage For most products, the partially sealed, low permeability MSAT containers and the completely sealed Polythene wraps scored highst for overall product quality. These treatments prevented the accumulation of undesirable CO₂ while at the same time protecting the produce against weightloss and consequent wilting. For some produce, especially berries, wilting was not apparent even in high permeability films such as acetates. B. Warm Storage For produce with high respiration rates (spinach, and berries) only acetate films were acceptable as wraps. The partially sealed low permeability films maintained good quality in warm storage but the high humidity within the package was conducive to micro-organism activity. Thus, in many cases samples disinfected prior to packaging in those films improved the warm storage quality. Disinfection also improved the quality of tomatoes and chopped salad mix in acetate wraps. Of the high permeability films, no significant difference was found among the Dupont acetate, Lumarith and Kodapak II. The type of seal also did not affect the characteristics of these wraps. The low permeability films differed principally in the amount of CO₂, retained by the container during storage. The Pliofilms retained the highest C0₂, levels followed by LSAT and then MSAT Cellophane. The sealed polyethylene, the single puncture and tent flap MSAT wraps exhibited similarity, especially with respect to C0₂ accumulation. The multiple puncture low permeability wraps showed characteristics between acetates and the last mentioned group. Correlation between CO₂ accumulation and off-flavor formation could be determined for most products. Higher CO₂ levels were tolerated at short storage intervals without off- flavor formation by most products but the rate of change in CO₂ tolerance varied from produce to produce. Correlation between % weightioss and degree of wilting could also be expressed as a function of the pre-packaging treatments used. Storage infection was eliminated by all films independent of the type of seal used. It should be emphasized that only a study of the resuits and relationships discussed under each product can serve as a basis for future work and commercial application of the methods presented in this work. / Graduation date: 1950

Compared to current planting practices using naked lettuce seed, precision planting coated lettuce seed can result in substantially reduced thinning costs, increases in number of marketable lettuce heads per acre, and higher average head weight. The use of coated seed, however, requires more attention to seedbed preparation, planting depths, irrigation schedules, and stand maintenance. Hill - dropping naked seed does not appear to offer advantages over conventional planting practices except in a slight reduction of seed cost per acre.

Lettuce varieties were compared in Cochise County for late spring and early fall harvests. The Great Lakes 659 types consistently performed as well as any in the trials for these times of year in this area.

Preliminary tests have been initiated in a program for control of Sclerotiniose, or drop of lettuce. Damping-off problems are concurrently being investigated.

A number of chemical compounds have been field evaluated as potential pesticides for control of insects on lettuce over the past several years. The important pests of fall planted lettuce being the cabbage looper, beet armyworm and corn earworm. In addition to the chemical compounds, the disease organism Bacillus Thuringiensis was used. It is slower in acting, but can be quite effective, particularly against the cabbage looper. Some of the chemical compounds which have been evaluated and are now available commercially are Sevin, Dibrom and Bidrin. This evaluation will continue as new and possibly more effective materials are made available.

Research work aimed at developing a selective mechanical harvester for crisphead lettuce was initiated in 1961. During the course of the project, two experimental machines were constructed. Commercial development of the harvester was assumed by Lockwood Grader Corporation in 1964 under terms of a contract between Lockwood and the Arizona Research Foundation. Lockwood is now in the process of constructing a four row prototype harvester that will be capable of harvesting 1.5 acres of lettuce per hour.

No description available.