Reduction In Nutritional Value Research Articles

Improvement and Evaluation of Honey Extractor

The traditional method of extracting honey leads to a reduction in nutritional value and quality thus, a honey extractor; a mechanical device that extracts honey from its comb was improved and evaluated using easily available materials. The main objective of this study is the improvement and performance evaluation of a honey extractor. The main functional parts of the machine are the net frame, wire mesh driving shaft, driving gear, operating handle to facilitate the winding process, and basket designed to hold and spin three honeycomb frames, constructed using a 1.5 mm thick aluminum sheet, placed vertically into the extractor. The honey extractor is cylindrical and operated by manually turning the operating handle. The time taken for honey extraction had a significant effect on the performance of the honey extractor; the machine capacity, efficiency, and weight of honey extracted decreased as the time taken for extraction increased, with optimum values of 93.37%, 40.46 kg/hr for machine efficiency, and capacity respectively. The machine is portable and can be operated without any special training or technical know-how, the machine also can preserve and leave the honeycomb undamaged after honey extraction.

Re-ensiling and microbial inoculant use effects on the quality of maize silages exposed to air

Re-ensiling has increased worldwide due to the increase in marketing of silage between farms. However, litlle is known about the aerobic deterioration and microbial inoculants effect in this process. The aim of this study was to determine the re-ensiling and microbial inoculant use effects on the maize silage quality. Experimental treatments included maize silage exposed to air for zero or 18 h, with or without microbial inoculant use containing a mixture of Lactobacillus plantarum and Propionibacterium acidipropionici. The forage was ensiled in 20 plastic buckets (20 liters capacity) with five repetitions per treatment. The silos were opened after 116 days and the chemical composition, in vitro dry matter digestibility (IVDMD), fermentative parameters, microorganism counts, total dry matter (DM) losses and aerobic stability of silage were evaluated. Re-ensiling reduced the non-fibrous carbohydrates content by 14.8%, whereas it increased the neutral detergent fiber content by 6%. The IVDMD was reduced by 6.1% in re-ensiled silages. In addition, re-ensiling increased the losses due to gases, effluents, and total DM. Lower lactic acid content and higher acetic acid content in re-ensiled maize silages were also observed. However, IVDMD increased by 4.6% in inoculated silages. Re-ensiling reduced the nutritive value and IVDMD of maize silages and should be avoided in production systems. The microbial inoculant use was not effective in improving the re-ensiled silage quality, which does not justify its use in these conditions. Farms should avoid purchasing maize silage due to reduction in nutritional value in the re-ensiling process. However, in some cases where farms need to purchase silage for feeding planning, the time between silo opening and re-ensiling should be as short as possible to reduce nutrient loss. Furthermore, in this situation the inoculant use does not improve silage conservation, which makes its use unnecessary.

Emergency seeding of cool‐season annuals into perennial grass after fall drought

AbstractSpring establishment of cool‐season annual grasses into poorly producing orchardgrass (Dactylis glomerata L) (OG) swards may improve forage production and nutritive value in the southeastern United States following a fall drought. A randomized complete block experiment was conducted where annual ryegrass (Lolium multiflorum Lam.) (AR) or forage oat (Avena sativa L.) (FO) was interseeded into an existing OG stand over three seeding dates with (+) or without (–) a burndown herbicide (BD) treatment and compared with an OG monoculture (control). In 2017, after a warm and wet winter, the OG monoculture (control) was able to produce sufficient forage mass (FM) without significant reduction in nutritive value as compared with OG interseeded with AR or FO. In 2018, OG had approximately 2,600 lb acre–1 less FM than in 2017, suggesting that recurrent fall drought with unfavorable winter conditions resulted in long‐term damage to the perennial sward. Meanwhile, treatments without BD did not show higher FM in the beginning of the season. Burndown treatment in general increased FM and nutritive value. An economic analysis of the study also revealed results suggesting that interseeding AR and FO in the spring is not economically viable, as it may cost up to 10 times as much as the control.

Intake and digestibility of nutrients during the grazing period in sheep on deferred marandu pastures with four initial heights

The objective of this study was to verify the effect of reducing in pasture height at the beginning of the deferment period (PHBD) of Brachiaria brizantha cv. Marandu on nutrient intake and digestibility in sheep during winter. The combinations between average sward heights (15, 25, 35 and 45 cm) at the beginning of the deferment period and the times of sward use during the winter were evaluated; intake and digestibility evaluations were carried out at the beginning, middle and end of the grazing period, which lasted 90 days. The experimental design used was completely randomized, with three replications. The parameters evaluated were: intake and digestibility of dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) and potentially digestible dry matter (pDDM). The pDDM contents were similar in pastures kept with 15 and 25 cm, but higher than those observed in pastures with 35 and 45 cm at the beginning of the deferment period. The NDF contents were lower and the CP and NDF digestibility were higher in 15 and 25 cm deferred pastures than in 35 cm at the beginning of deferment period, except for pastures lowered to 45cm. The improvement in nutritional value of the forage apparently ingested by sheep, promoted by ISP reduction, did not result in a variation in pasture consumption by the animals. DMI, expressed as percentage of body weight (%BW), ranged from 1.10 to 1.63. At the beginning of the grazing period, higher values of pDDM, CP and DM digestibility (DMD) were verified in simulated grazing samples. The same response pattern observed for nutritional value traits also occurred for DMI (g.day-1 and %BW) and CP intake. These were higher at the beginning, than at the middle and end of the grazing period. The use of lower sward heights at the beginning of the deferment period allowed the production of pasture with better nutritional quality, but these changes in the nutritional value of the pasture were insufficient to result in higher nutrient intake and digestibility. Furthermore, there was a reduction in nutritional value of the forage apparently consumed by sheep, in the intake and digestibility of deferred pastures throughout the grazing period, in winter. The lower pastures at the beginning of the deferment period (15 cm) improves the nutritional value of forage and nutrient digestibility at the beginning of the winter grazing period. The nutritional value and intake of deferred forage by sheep are compromised by the grazing period.

Effect of heat treatment on the structure and digestion properties of oat globulin

AbstractBackground and objectivesThe heat treatment required for deactivation of enzymes was carried out in crop species such as oats to retain its desirable shelf life, but it may lead to a reduction in nutritive value and denaturation of globulin. This study compared the effect of two heat treatments, stirring roasting (240°C, 15 min; OFG) and kiln roasting (140°C, 45 min; OMG), on structure and digestion properties of oat globulins.FindingsThe results showed that compared with control oat globulin (OCG), both heat treatments decreased the content of amino acid in the oat globulins. The increase in roasting temperature (from 140°C to 240°C) led to the change in the secondary structure in oat globulins, with a decrease in β‐sheet and β‐turn contents, and an increase in α‐helix and random coil contents. Scanning electron microscopy showed that the structure of OFG was fragmented into small clumps. Compared with kiln roasting (140°C), stirring roasting (240°C) decreased average molecular weight, peak viscosity, and denaturation enthalpy but increased viscosity and in vitro digestibility of oat globulin.ConclusionsCompared with kiln roasting, stirring roasting increased in vitro digestibility of oat globulin and contributed to the taste, but the nutritional loss was greater.Significance and noveltyTwo heat treatment methods for enzymatic inactivation were compared regarding the effect on the structure and in vitro digestibility of oat globulin, indicating that higher temperature increased digestibility of oat globulin.

Nitrogen's influence on stockpiling of ‘Jesup’ tall fescue cultivars with diverse fungal endophyte presence

AbstractTall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] is used in the southern United States to extend the cow–calf grazing season during autumn and winter by stockpiling. However, livestock producers are reluctant to graze tall fescue because of the toxicity associated with the presence of an endophyte within the grass plant. In this study, the effects of the amount of N fertilizer rate (0, 50, and 100 acre–1), the N source (ammonium nitrate and urea), and the date of N application (September and October) were evaluated for the herbage accumulation (HA) and nutritive value on stockpiled tall fescue. The study was conducted in the autumn of 2007–2009 with six experimental ‘Jesup’ tall fescue cultivars with different endophytic fungal strains: endophyte‐infected wild‐type, endophyte‐free, and infected with the novel endophytes (NE) AR502, AR514, AR542, and AR584. Greater HA was observed with the September N application. Ammonium nitrate was more efficient at increasing HA than urea at both N application rates. Herbage accumulation increased by 56 and 98% at 50 and 100 lb N acre–1 compared with the control. The nutritive value of the stockpiled tall fescue declined as the winter season advanced, despite the source, rate, and timing of fertilizer application. Although the study reported a reduction in nutritive value from November to January, the nutritive value concentrations and estimations are considered optimum for livestock production.

Effect of Saccharomyces uvarum on lipid oxidation and carbonyl compounds in silver carp mince during cold storage.

Fish lipid is highly susceptible to oxidation, resulting in accumulation of toxic substances reactive carbonyl compounds (RCCs), the reduction of nutritional value, and the production of odorous substances. In this study, the effect of yeast (Saccharomyces uvarum) on RCCs, fat acid composition, volatiles, and sensory traits in silver carp mince stored at 4°C was evaluated. Yeast eliminated malondialdehyde, 4‐hydroxyl‐2‐hexenal, and 4‐hydroxyl‐2‐nonenal by about 80%, 68%, and 60%, which increased by about 170%, 340%, and 300% in the control, respectively. Yeast helped retain about 80% of the polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), respectively; only about 53% and 46% of EPA and DHA, respectively, were maintained in the control. Yeast removed off‐odors hexanal, nonanal, and decenal, resulting in enhanced sensory traits. These findings were economically important for improving the quality of fish products. It might present an approach to improve the flavor of fish products.

Effect of harvesting stage on yield and nutritive value of Buffel grass (Cenchrus ciliaris Linn) under irrigation at Gewane district, north eastern Ethiopia

A study was carryout to determine the biomass yield, chemical composition and in-vitro dry matter digestibility of irrigated Cenchrus Ciliaris. The treatments had three harvesting days (60, 90 and 120) in randomized complete block design (RCBD). Stage of harvesting days had significant influence (p< 0.05) on the biomass and chemical composition of Cenchrus Ciliaris. With longer days of harvesting, there was a reduction in nutritive value of the grass; whereas at longer day of harvesting, there was the highest biomass yield. DMY, NDF, ADF and ADL and plant height were positively correlated to each other but negatively correlated to LSR, CP, total ash, and IVDMD. Biomass yield of Cenchrus Ciliaris was positively correlated with delaying stage of harvesting but nutritive value in Cenchrus Ciliaris, were negatively correlate with increasing stage of harvesting. Eventually, harvesting of Cenchrus ciliaris at 90 days had good nutritive (10.62 % CP and 12.3t/ha DM) value and biomass yield. So that, this finding creates an opportunity for the pastoralists and agro-pastoral community along the Awash River to resolve the scarcity of feed and increase the livestock productivity in the study area.

Down-regulation of lycopene ε-cyclase expression in transgenic sweetpotato plants increases the carotenoid content and tolerance to abiotic stress

Carotenoids are required for many biological processes in plants and humans. Lycopene ε-cyclase (LCY-ε) catalyzes the conversion of lycopene into lutein via the α-branch carotenoid biosynthesis pathway. Down-regulation of IbLCY-ε by RNAi increases carotenoid accumulation and salt stress tolerance in transgenic sweetpotato calli. As the role of IbLCY-ε in carotenoid biosynthesis and environmental stress responses in whole plants is poorly understood, transgenic sweetpotato (RLE plants) with reduced expression of IbLCY-ε were developed. RLE plants contained higher levels of total carotenoid and β-carotene, due to an elevated β-carotene/lutein ratio rather than increased de novo biosynthesis. RLE plants showed high reactive oxygen species/radical-scavenging activity. They also exhibited an enhanced tolerance of both salt and drought stress, which was associated with lower membrane permeability and a higher photosynthetic rate, respectively. Elevated carotenoid accumulation in RLE plants mitigated the reductions in leaf photosystem II efficiency and chlorophyll induced by abiotic stress. Expression of the carotenoid cleavage genes 9-cis-epoxycarotenoid dioxygenase, carotenoid cleavage dioxygenase 1 (CCD1) and CCD4 was higher in RLE plants, as was abscisic acid accumulation. IbLCY-ε silencing thus offers an effective approach for developing sweetpotato plants with increased tolerance to abiotic stress that will grow on global marginal lands with no reduction in nutritional value.

Extreme reduction in nutritional value of a key forage fish during the Pacific marine heatwave of 2014-2016

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 613:171-182 (2019) - DOI: https://doi.org/10.3354/meps12891 Extreme reduction in nutritional value of a key forage fish during the Pacific marine heatwave of 2014-2016 Vanessa R. von Biela1,*, Mayumi L. Arimitsu2, John F. Piatt1, Brielle Heflin2, Sarah K. Schoen1, Jannelle L. Trowbridge1,3, Chelsea M. Clawson1,4 1US Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, Alaska 99508, USA 2US Geological Survey, Alaska Science Center, 250 Egan Dr., Juneau, Alaska 99801, USA 3University of Alaska Anchorage, Alaska Native Science & Engineering Program, 3211 Providence Drive, Anchorage, Alaska 99508, USA 4Alaska Sea Grant Marine Advisory Program, 1007 W 3rd Avenue, Suite 100, Anchorage, Alaska 99501, USA *Corresponding author: vvonbiela@usgs.gov ABSTRACT: Pacific sand lance Ammodytes personatus are a key forage fish in the North Pacific for many species of salmon, groundfish, seabirds, and marine mammals and have historically been important to predators in relatively warm years. However, extreme declines in the nutritional value of sand lance in Prince William Sound, Alaska, USA, during 2012-2016 indicate that energy transfer from lower trophic levels to predators via sand lance may have been disrupted during the North Pacific marine heatwave in 2015 and 2016. Nutritional value (length, energy density, and whole-body energy) was measured in age-0 and age-1 sand lance collected during July in cool (2012-2013) and increasingly warm (2014-2016) years. The value of age-0 fish was relatively stable, with only minor differences among years for length and whole-body energy. By contrast, the value of age-1 fish significantly declined in 2015, and by 2016 they were 38% shorter and 13% lower in energy density compared to cooler years. This contributed to significant declines in whole-body energy of 44% in 2015 and 89% in 2016 compared to cooler years (2012-2014). The 2015 sand lance cohort experienced little growth or lipid accumulation from July 2015 at age-0 to July 2016 at age-1. This effective disruption of energy flow through pelagic food webs probably contributed to population declines and/or breeding failures observed among several predators in the Gulf of Alaska and suggests that tipping points were reached during the heatwave. KEY WORDS: Pacific sand lance · Ammodytes personatus · ‘The Blob’ · Gulf of Alaska · Body condition · Energy density Full text in pdf format PreviousNextCite this article as: von Biela VR, Arimitsu ML, Piatt JF, Heflin B, Schoen SK Trowbridge JL, Clawson CM (2019) Extreme reduction in nutritional value of a key forage fish during the Pacific marine heatwave of 2014-2016. Mar Ecol Prog Ser 613:171-182. https://doi.org/10.3354/meps12891 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 613. Online publication date: March 21, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

A comparative study of black mulberry juice concentrates by thermal evaporation and osmotic distillation as influenced by storage

Abstract In the present study, black mulberry juice was concentrated using thermal evaporation and osmotic distillation after clarification and pasteurization. The main quality parameters of the concentrates were comparatively investigated after reconstitution with different storage times and temperatures. The parameters investigated were: color, turbidity, pH, titratable acidity, anthocyanin content, percent polymeric color, antioxidant activity, 5-hydroxymethylfurfural (HMF) content and volatile profile. The anthocyanin content, volatile content and turbidity values of osmotically distillated samples were found to be higher than those of the thermal concentrates. Neither HMF nor furfural was detected in the samples soon after the processing; however, levels of process contaminants were found to increase gradually throughout the storage period in both concentrates. Thermal evaporation resulted in markedly higher HMF and furfural formation in comparison to the osmotic distillation process. The anthocyanin content and antioxidant activity of the concentrates decreased, whereas polymeric color ratio and turbidity values increased within longer storage time and higher storage temperature. Industrial relevance Concentration is one of the key steps affects the chemical and physical properties of black mulberry juice since black mulberry phytochemicals, mainly anthocyanins, are labile to heat treatment and storage. Thermal evaporation has some drawbacks such as loss of fresh juice flavors, color degradation, reduction of nutritional value and formation of mutagenic compounds such as HMF and furfural. These drawbacks require alternative methods that involve minimal processing. Osmotic distillation can be recommended for black mulberry juice concentration in order to preserve its heat-sensitive components and to produce high-quality product.

Which Milk is Fresh?

The different heat treatments to which milk is subjected and their effects on milk were reviewed. Pasteurized and UHT milk which is mislabelled as 'fresh milk' in the Philippines were compared. The commercial heat treatment processes applied to milk are: pasteurization, ultra high temperature (UHT), ultra pasteurization or super pasteurization, sterilization, and innovative steam injection (ISI). It was shown that commercial heat treatment processes alter the heat sensitive nutrients, physico-chemical and functional properties of milk. Higher amounts of lysinoalanine were found in UHT milk than in pasteurized milk. Further reduction in nutritional value of UHT milk occurs in supermarket shelves where it is kept until sold and consumed. While UHT treatment is suitable for tropical countries with high ambient temperatures and are unable to afford refrigeration during marketing and distribution, the nutritional quality of protein is very important because in these countries, protein intake is generally low due to poverty. The Philippine food regulatory agency allows the 'fresh milk' label on UHT milks marketed in the country. This practice does not properly inform the consumers about the product because such milks may have been in the supermarket shelves for 6 months or more and is therefore, no longer fresh. It also puts the locally produced fresh, pasteurized milk at a disadvantage. Although liquid milk for direct consumption is not covered by Codex commodity standards, use of terms like 'natural', 'pure', 'fresh', 'home made', and 'artisan' needs to be regulated in order to protect the consumers.

Long‐term effects on sward composition and animal performance of reducing fertilizer inputs to upland permanent pasture

AbstractThis study investigated the long‐term effects on sward composition and animal performance of applying different fertilizer regimes to upland permanent pasture. The experiment, which was carried out in 2008, was based on a set of replicated (n = 3) plots that had been established in 1990. The effects of applying (i) N, P, K and lime, (ii) P and K plus lime and (iii) lime only were compared with a treatment that received no nutrient applications. Using a put‐and‐take stocking system, the plots were grazed to a target sward surface height of 4 cm by ewes and lambs from April to early August and by ewes only from August to mid‐October. The long‐term reduction in nutrient inputs had led to decreases in the percentages of both sown and unsown grass species within the sward (P < 0·05), and an increase in the percentage of mosses and litter (P < 0·05), with a corresponding reduction in nutritional value. Although there were no statistically significant treatment‐related differences in lamb growth rates, lower fertilizer inputs were associated with a marked decline in stock carrying capacity and associated overall productivity during both the pre‐ and post‐weaning periods (P < 0·001). The findings highlight the challenges faced when attempting to reconcile production and environmental objectives in upland systems.

Effect of extrusion under controlled temperature and moisture conditions on ileal apparent amino acid and starch digestibility in peas determined with young broilers

The objective of the experimental programme was to examine the influence of extrusion of peas under controlled temperature and moisture conditions on coefficient of ileal apparent digestibility (CIAD) of amino acids and to examine the changes to starch structure (crystallisation) and subsequent effects on CIAD of starch in young broilers. Experiment 1 used one pea cultivar (2.94 mg trypsin inhibitor units (TIU)/g DM) processed under two extrusion temperatures (exit temperatures of 70 and 140 °C) and two moisture levels (0 and 1.96l water added/h) giving a 2 × 2 factorial design (with a 5th treatment being the raw pea sample). All pea samples were added at a rate of 500 g/kg into a purified diet where peas were the only source of protein/amino acids. Processing generally led to a reduction in CIAD of amino acids but CIAD of starch for Raw, Treatments 1 and 3 (added water) was lower than that for Treatments 2 and 4 (no water) with data of 0.730, 0.808 and 0.759 vs. 0.852 and 0.834, respectively. Experiment 2 evaluated two near-isogenic lines of peas (HA5 and HB5) processed under the same conditions as for Experiment 1. Extrusion at 70 °C/addition of water had no significant effect on trypsin inhibitor activity but the inhibitor was eliminated at 140 °C with or without addition of water (P<0.001). Pea line HA5 generally had higher CIAD than HB5 (P<0.05 for cystine, lysine, leucine, histidine, alanine; P<0.01 for threonine). There were significant temperature × water addition interactions for CIAD (P<0.001 for all amino acids except methionine; P=0.006). For example, data for lysine were 0.760, 0.828, 0.860 and 0.759, respectively for 140 °C/no water, 140 °C/1.96 l/h, 70 °C/no water and 70 °C/1.96 l/h. CIAD for starch improved following processing, attributed to the loss of crsytallinity. The data indicate that peas are sensitive to high processing temperatures which are associated with a reduction in nutritive value, in terms of amino acid digestibility, for young poultry. In contrast, the results reinforce the adverse effect of crystallinity on starch digestibility and show that extrusion in the absence of water improves the digestibility of raw starches due to granular disorganisation (as evidenced by X-ray diffraction patterns) and changes in crystallinity.

Effects of shrub encroachment on herbage production and nutritive value in semi‐arid Mediterranean grasslands

AbstractThere is limited information on the effects of the increase in the density of shrubs on herbage production and nutritive value of natural grasslands in the Mediterranean region, currently facing major land use changes. Herbage production of drymatter (herbaceous fractions, of plant functional groups and by species), crude protein (CP), neutral‐detergent fibre (NDF), acid‐detergent fibre (ADF), acid‐detergent lignin (ADL) and hemicellulose concentrations and in vitro organic matter digestibility were determined at the time of peak of annual growth across four types of grassland vegetation each characterized by different shrub cover regimes. A sharp reduction in herbage production and a reduction in nutritive value were found as a result of the increase in shrub cover. These changes appeared to be closely related to the shift in plant functional groups detected as shrub density increased. Herbage production from grasses and legumes was found to be more sensitive to shrub cover changes than herbage production from forbs, whereas, as grassland types became denser, annual species were gradually replaced by perennials and C4 grasses by C3 ones. The impact of shrub encroachment on Mediterranean grasslands is discussed in relation to their use by livestock.

Studies on pest infestation of commercial samples of cowpeas and maize Marketed in Owerri, Imo State, Nigeria

Samples of different varieties of brown beans, Vigna unguiculata and white maize, Zea mays randomly purchased from two open markets in Owerri, Imo State were studied for pest infestation. The grains were examined with x2 magnification hand lens for the eggs, larvae and adults of the pests. Callosobruchus maculates (Olivier) and Sitophilus zeamais (Motsch) were identified as insect pests infesting beans and maize respectively. On the overall, 43.3% of 7565 cowpea and 30.8% of 4640 of maize grains respectively were infested. Eggs, larvae, pupae and adults of the insect pests were recovered from both the beans and maize samples. In beans, eggs of C. maculates were found only on the pericarp while the larvae, pupae and adults were recovered from both the pericarp and from within the endosperm of the seeds. In the maize, the eggs, larvae and pupae of S. zeamais were located in the endosperm only, while the adults were found in both the endosperm and the outer surfaces of the grains. Weight loss as an index of degree of damage to the samples ranged from 23.3% to 35.7% in beans and 19.3% to 55.7% in maize. Weight loss in both the infested beans and maize increased with increase in the number of emergence holes. Public health implications of the insect infestation of the stored products such as reduction in nutritive value and accumulation of undesirable residues were discussed. Improved storage and pest control techniques are recommended. Keywords : pest, infestation, cowpea, maize, Nigeria International Journal of Natural and Applied Sciences Vol. 1(1) 2005: 5-9

Accurate determination of hexanal in beef bouillons by headspace solid‐phase microextraction gas‐chromatography mass‐spectrometry

Lipid oxidation has great impact on the quality of food products through flavor and taste deterioration, reduction in nutritive value, and potential toxicity of the oxidized food components. Flavor and taste deterioration can be easily perceived and it represents one of the major causes of consumer complaints in the food industry. The deterioration of sensory properties is due to the decomposition products of hydroperoxides that easily isomerize and degrade into volatile compounds. Volatile products are responsible for flavor and taste deterioration. In this study, we present the development of the solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS) technique to quantify low amounts (μg/g range) of secondary oxidation products, i.e. hexanal. The optimization of SPME parameters is a difficult task because of the possibility of further formation of volatile products during analysis. Different parameters such as type of fiber, exposure time of the fiber to the sample headspace and the optimal temperature of absorption have also been investigated. The complete validation of the method was achieved by the determination of linearity, limits of detection and quantification and repeatability. We demonstrated that the SPME method is a valuable tool for the quantification of low amounts of secondary oxidation products such as hexanal. Therefore, this technique can be used to detect early formation of volatiles.

The influence of the broccoli (Brassica oleracea var. itálica)fill weigth on postharvest quality

Broccoli is a vegetable of important economic value as well as a source of vitamin C and anticarcinogenic property substances. Although it can be minimally processed, this vegetable presents fast senescence, characterized by yellowing, loss of turgescence, development of off-odors, increase in enzymatic activity and reduction of nutritional value. Among the frequently used techniques that can extend the shelf-life of minimally processed broccoli, we have the use of cool storage and modified atmosphere packaging (MAP). Several factors interfere in the efficiency of MAP, influencing the speed and intensity of the changes on atmosphere composition. This work aimed to study the influence of the amount packaged broccoli on its postharvest quality, when stored at 1oC. Results demonstrated strong influence of the use of MAP compared to control treatment. It was observed that for all packaged treatments there was better vitamin C retention, lower loss of weight, lower peroxidase activity and better turgidity score of broccoli. This study demonstrated that the treatments with higher amounts of product showed the worst performance on vitamin C and aroma evaluation. The peroxidase activity was also influenced, and the best results were found in the treatment with higher amounts, which presented lowest values. However there is a tendency of increase in the activity along the time, especially at the end of the experiment. It was not detected the influence of the fill weight about color evaluation.

Sugar formulation effect on available lysine content of dulce de leche.

Dulce de leche is a dairy-based confectionery product, widely consumed in Argentina and other Latin American countries as filling or topping for desserts, cakes and biscuits (Hansen, 1978; Bouzas, 1997). It is prepared by heat concentration of whole milk with added sucrose until it reaches 700 g total solids/kg dulce de leche. Sucrose is usually partly replaced by other sugars (not more than 400 g/kg of total sugars added according to Normas Mercosur, 1996) to avoid crystallization. Sodium bicarbonate is added to prevent coagulation of proteins as the pH of the mixture decreases and the isoelectric pH of proteins increases during heating.Maillard browning is the main reaction of milk proteins during the manufacture of dulce de leche. This results in an attractive flavour and colour, but also leads to less desirable changes, such as loss of nutritional value and formation of toxic compounds (Rizzi, 1994; Friedman, 1996a). The natural reactants are free amino groups of milk proteins and lactose. However, as the addition of other reducing sugars is an accepted practice, the consequences may be quite different depending on the formulation used. In addition, other reactions leading to crosslinkages between protein chains contribute to the reduction in nutritional value (Mauron, 1990; Friedman, 1996b; Finot, 1997). The reduction of nutritional quality of milk proteins is attributed to the lower digestibility and the biological inactivation or destruction of essential amino acids. Lysine is the essential amino acid most affected as its free ε-amino group is very reactive (Hurrell, 1990; Mauron, 1990; Finot, 1997).Several studies have investigated the physical and rheological characteristics (Pauletti et al. 1984, 1996), sensory properties (Sabioni et al. 1984; Buera et al. 1990; Hough et al. 1990), sugar composition and microbiological stability (Ferramondo et al. 1984) of dulce de leche. However, there is little information about the loss in available lysine during manufacture (Pavlovic et al. 1994).The aim of this study was to examine the effects of the nature and quantity of various sugars commonly used in the manufacture of dulce de leche on the loss of available lysine.

Pre-harvest pearl millet tillers and leaves as animal food.

Feeding experiments with pre-harvest tillers and leaves of 2 varieties of pearl-millet were conducted on a research station in semi-arid Mali. Tillers were harvested at 45 to 65 days after sowing (DAS) and fed green. Leaves were harvested at 65 to 85 DAS and fed to sheep or cattle green or after 8 months conservation as hay or as silage. Intake of organic (IOM) was higher for green leaves than for tillers, showing no difference for the 2 varieties used. In vivo digestible organic matter (DOM) was highest tillers in both varieties. Nutritive value of tillers and green leaves met the quality criteria for a maintenance diet of sheep. During conservation of millet leaves, the reduction in nutritional value was less with hay than with silage. Small amounts of silage offered as a supplement to rice straw helped to meet maintenance requirements for metabolizable energy. Conserved as hay, a quality forage was obtained which on an economic scale compensated for grain yielded losses when fed to selected animals.