Evaluating nitrogen utilization efficiency of nonpregnant dry cows offered solely fresh cut grass at maintenance levels

The present study aimed to identify key parameters influencing N utilization and develop prediction equations for manure N output (MN), feces N output (FN), and urine N output (UN). Data were obtained under a series of digestibility trials with nonpregnant dry cows fed fresh grass at maintenance level. Grass was cut from 8 different ryegrass swards measured from early to late maturity in 2007 and 2008 (2 primary growth, 3 first regrowth, and 3 second regrowth) and from 2 primary growth early maturity swards in 2009. Each grass was offered to a group of 4 cows and 2 groups were used in each of the 8 swards in 2007 and 2008 for daily measurements over 6 wk; the first group (first 3 wk) and the second group (last 3 wk) assessed early and late maturity grass, respectively. Average values of continuous 3-d data of N intake (NI) and output for individual cows ( = 464) and grass nutrient contents ( = 116) were used in the statistical analysis. Grass N content was positively related to GE and ME contents but negatively related to grass water-soluble carbohydrates (WSC), NDF, and ADF contents ( < 0.01), indicating that accounting for nutrient interrelations is a crucial aspect of N mitigation. Significantly greater ratios of UN:FN, UN:MN, and UN:NI were found with increased grass WSC contents and ratios of N:WSC, N:digestible OM in total DM (DOMD), and N:ME ( < 0.01). Greater NI, animal BW, and grass N contents and lower grass WSC, NDF, ADF, DOMD, and ME concentrations were significantly associated with greater MN, FN, and UN ( < 0.05). The present study highlighted that using grass lower in N and greater in fermentable energy in animals fed solely fresh grass at maintenance level can improve N utilization, reduce N outputs, and shift part of N excretion toward feces rather than urine. These outcomes are highly desirable in mitigation strategies to reduce nitrous oxide emissions from livestock. Equations predicting N output from BW and grass N content explained a similar amount of variability as using NI and grass chemical composition (excluding DOMD and ME), implying that parameters easily measurable in practice could be used for estimating N outputs. In a research environment, where grass DOMD and ME are likely to be available, their use to predict N outputs is highly recommended because they strongly improved of the equations in the current study.

Multivariate analysis of fresh-cut carambola slices stored under different temperatures

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Use of modified atmosphere to extend shelf life of fresh-cut carambola (Averrhoa carambola L. cv. Fwang Tung)

Fresh-cut fruit products, including carambola (Averrhoa carambola L.), have limited marketability due to cut surface browning attributed to phenolic compound oxidation by enzymes, such as polyphenol oxidase (PPO). The objective of this study was to evaluate postharvest changes in carambola slices in three different packages. Carambola fruit (cv. Fwang Tung) were picked from the Estacao Experimental de Citricultura de Bebedouro orchard at the mature-green stage. The fruit were washed, dipped in NaOCl solution (200 mg L-1 for 5 min), stored overnight at 10 degrees C, then manually sliced into pieces of approximately 1 cm. The slices were rinsed with NaOCl solution at 20 mg L-1, drained for 3 min, and packaged in polyethylene terephthalate (PET) trays (Neoform (R) N94); polystyrene trays covered with PVC 0.017 turn (Vitafilm (R), Goodyear); and vacuum seated polyolefin bags (PLO, Cryovac (R) PD900). The packages were stored at 6.8 degrees C and 90% RH for 12 d, with samples taken every 4 d. PET trays and PVC film did not significantly modify the internal atmosphere and the high water permeability of PVC led to more rapid slice desiccation. PPO activity was lower when the slices were packaged in PLO vacuum sealed bags, which reduced degreening and led to better appearance maintenance for up to 12 d. (R) 2006 Elsevier B.V. All rights reserved.

Impact of atmosphere, organic acids, and calcium on quality of fresh-cut 'Kensington' mango

Fresh-cut slices from ripe 'Kensington' mango (Mangifera indica L.) were prepared aseptically and stored under various treatments at 3 degrees C. Treatments included reduced oxygen (2.5%), enhanced carbon dioxide (5-40%), organic acid application, calcium chloride application, and combinations of the above. Symptoms limiting shelf-life were characterised by tissue darkening, development of a 'glassy' appearance, surface desiccation, and loss of firmness. Reduced oxygen (2.5%) was effective at controlling tissue darkening and the development of a 'glassy' appearance, while calcium application (3%) was partly effective at controlling darkening. Calcium chloride however significantly slowed (but did not stop) loss of tissue firmness. Carbon dioxide (5-40%) and citric acid had little positive effect on shelf-life, with both treatments appearing to promote tissue softening. A combination of low oxygen and calcium allowed 'Kensington' slices to be held for at least 15 days at 3 degrees C. (C) 2006 Elsevier B.V All rights reserved.

Production and preservation of fresh-cut 'Tommy Atkins' mango chunks

During the 1999/00 and 2000/01 seasons, sliced 'Tommy Atkins' mangoes were packaged with three different types of polymeric films; polypropylene (PP) cups, low-density polyethylene (LPDE) bags or polyethylene terephthalate (PET) clamshell trays, and stored at 3°C for 2 weeks. The mango chunks were evaluated for flavor, appearance, colour, total soluble solids (TSS), total titratable acidity (TTA), ascorbic acid (AA) contents, O2 and CO 2 concentration in the packages, as well as respiration. Shelf life based on visual appearance was 14 days, with the products showing good appearance and agreeable aroma. The TTA content in chunks packaged in PP cups or PET trays were reduced during the storage, and with the color changing from light yellow to dark yellow. The chunks respiration in PP cups or LPDE bags were 64.6 and 87.9 mL CO2.kg-1.h-1, and in PP cups or PET trays were 45.86 and 43.92 mL CO2.kg-1.h -1, respectively for 1999/00 and 2000/01 seasons. The percentages of O2 and CO2 in the packages were stabilized after 2-4 hours, and the atmosphere had 11-17% and 1-10% of them. The microbiological content was lower than the allowed. No differences were observed between the seasons, and the best packages were the cups.

Use of carambola (Averrhoa carambola L. 'Fwang Tung') fruit at two stages of maturity for fresh-cut products

Carambola fruit ('Fwang Tung') were picked at two stages of maturity: mature-green (50% yellow) and mature (100% yellow). Fruit were washed with water, dipped in NaOCl solution (200 mg.L-1 for 5 minutes), and stored over night at 10°C. Fruit were sliced manually in to pieces of approximately 1 cm thickness. Slices were rinsed with NaOCl solution at 20 mg.L-1, drained for 3 minutes, and packaged in polyethylene tereftalate (PET) trays provided with a fit cover (Neoform® N94). Packages were stored at 6.5°C and 85% RH for 9 days, and samples taken every 3 days for physical, chemical and biochemical analysis, respiration, and internal atmosphere composition. Immediately after cutting, slices at both stages of maturity showed a wounding response with a 5-fold increase in respiration rate. Polygalacturonase (PG) and polyphenol oxidase (PPO) activity did not differ between stages of maturity. Despite the less mature stage being less preferred at the sensory evaluation owing to its greenish peel, the best stage of maturity for carambola fresh-cut production was mature-green, due to a higher resistance to cutting, and presenting a better colour and appearance maintenance for up to 9 days.

Respiratory and storage behavior of fresh cut 'Tommy Atkins' mango

The respiratory and storage behavior of fresh cut 'Tommy Atkins' mango, naturally ripened (NR) or with use of ethylene (RE), were studied. Fruits were selected, washed and disinfected (200 mgCl.L-1) and stored for 12 hours at 10°C. After this period, they were processed under hygienic conditions at 10°C, packaged in polyethylene terephthalate (PET) trays or in styrofoam trays wrapped with stretchable polyvinyl chloride (PVC) film and stored for up to 15 days at 3°C. The products were evaluated regarding the evolution of internal atmosphere in the packing (O2 and CO 2), development of weight, appearance, shelf life and consumer acceptability. The respiratory rate was measured before and after processing every two hours. The yield of 'Tommy Atkins' mango to produce fresh cut product was 48.09±0.95%. Increase of the respiration rate of both mango samples was verified one hour after the preparation (NR = 17.75 mL CO 2.kg-1.h-1; RE = 28.29 mL CO 2.kg-1.h-1), followed by stabilization at 3.76 and 8.07 mL CO2/kg.h, respectively. The percentage of O2 in packages was stable in all treatments, 15-20% in PVC trays, 18-20% in PET tray. The percentage of CO2 was steady around 1.5-2.5%. The products lost fresh mass during the storage, from 0.06% to 0.30% for PET trays and from 0.15% to 1.61% for trays covered with PVC. The appearance was considered appropriate for commercialization until the 13th day, whereas product from mangoes ripened with application of ethylene was for 11 days, presenting browning in the external surface. The naturally ripened mango presented the best flavor and consumer preference in relation to the mango ripened with application of ethylene for 11 days of storage. The control of hygienic conditions during the production and storage was good and with safety for until 10 days.

Use of modified atmosphere to extend shelf life of fresh-cut carambola (Averrhoa carambola L. cv. Fwang Tung)

Fresh-cut fruit products, including carambola (Averrhoa carambola L.) have limited marketability due to cut surface browning attributed to oxidation of phenolic compounds by enzymes such as polyphenol oxidase (PPO). The objective of this study was to evaluate postharvest changes of carambola slices in three different packagings. Carambola fruit (cv. Fwang Tung) were picked from the orchard of Estação Experimental de Citricultura de Bebedouro at mature-green stage. Fruit were washed, dipped in NaOCl solution (200 mg.L -1 for 5 minutes), and stored overnight at 10°C. Fruit were manually sliced into pieces of approximately 1 cm. Slices were rinsed with NaOCl solution at 20 mg.L-1, drained for 3 minutes, and packaged in polyethylene terephthalate (PET) trays (Neoform N94); polystyrene trays covered with PVC 0.017 mm (Vitafilm - Goodyear); and vacuum sealed polyolefin bags (PLO, Cryovac PD900). The packages were stored at 6.8°C and 90%RH for 12 days and samples taken every 4 days. PET trays and PVC film did not significantly modify internal atmosphere and the high water permeability of PVC led to more rapid slice desiccation. PPO activity was lower when slices were packaged in PLO vacuum sealed bags, which reduced discolouration and led to better appearance maintenance for up to 12 days.

Effect of natural antimicrobials on microbiological and sensorial quality of fresh-cut cantaloupe melon

The effect of different natural antimicrobials on the microbiological and sensorial quality of fresh-cut Cantaloupe melons stored up to 10 days at 5°C was examined. Pieces of melon were washed for 1 min at 5ºC in water (control), vanillin (1000 mg/L and 2000 mg/L) or cinnamic acid (148.16 mg/L and 296.32 mg/L). Other antimicrobial treatments consisted of packaging the pieces of melon with an antimicrobial pad which contained cinnamic acid (148.16 mg/L and 296.32 mg/L). After 10 days of storage, significant differences among antimicrobials treatments and water treatment were found. In water treatment, the psychrotroph load was 3.63 ± 0.09 log cfu g-1 meanwhile on all antimicrobial treatments the values ranged from 3.04 ±0.13 log cfu g-1 to 3.28±0.1 log cfu g-1. Mesophilic growth in the control treatment averaged 6.79±0.06 log cfu g-1 meanwhile on antimicrobial treatments the counts were from 5.15±0.01 log cfu g-1 to 5.30±0.03 log cfu g-1. Total coliform levels were 7.8±0.1 log cfu g-1 when melon was washed in water, followed by washing with cinnamon (296.32 mg/L) at 6.5 log cfu g-1 and for the rest of the treatments were around 5.5 log cfu g-1. The treatments did not display differences among mould and yeast growth after 10 days of storage. The sensorial quality decreased throughout storage. However, at the end of storage, the scores ranged between 6.5 and 7, above the minimum level for marketability (level 5). Sensorial panelist noted a ‘sweet’ taste when vanillin was used as sanitizer. In all antimicrobial treatments, no relation was found between a higher dose and a higher microbial reduction. So, vanillin at 1000 mg/L in water or cinnamic acid at 148.16 mg/L provided in water dip or as a pad inside the trays could be optimal natural sanitizers to substitute the use of chlorine in fresh-cut products as Cantaloupe melon.

Multivariate analysis of fresh-cut carambola slices stored under different temperatures

Quality of fresh-cut carambola (Averrhoa carambola L) is related to many chemical and biochemical variables especially those involved with softening and browning, both influenced by storage temperature. To study these effects, a multivariate analysis was used to evaluate slices packaged in vacuum-sealed polyolefin bags, and stored at 2.5 degrees C, 5 degrees C and 10 degrees C, for up to 16 d. The quality of slices at each temperature was correlated with the duration of storage, O(2) and CO(2) concentration in the package, physical chemical constituents, and activity of enzymes involved in softening (PG) and browning (PPO) metabolism. Three quality groups were identified by hierarchical cluster analysis, and the classification of the components within each of these groups was obtained from a principal component analysis (PCA). The characterization of samples by PCA clearly distinguished acceptable and non-acceptable slices. According to PCA, acceptable slices presented higher ascorbic acid content, greater hue angles ((o)h) and final lightness (L-5) in the first principal component (PC1). On the other hand, non-acceptable slices presented higher total pectin content. PPO activity in the PC1. Non-acceptable slices also presented higher soluble pectin content, increased pectin solubilisation and higher CO(2) concentration in the second principal component (PC2) whereas acceptable slices showed lower total sugar content. The hierarchical cluster and PCA analyses were useful for discriminating the quality of slices stored at different temperatures. (C) 2011 Elsevier B.V. All rights reserved.

Innovative treatments for shelf-life extension of whole and fresh-cut fruit

Maintaining the postharvest quality of whole and fresh-cut fruit during storage and distribution is the major challenge facing fruit industry. For this purpose, industry adopt a wide range of technologies to enable extended shelf-life. Many factors can lead to loss of quality in fresh product, hence the common description of these products as ‘perishable’. As a consequence normal factors such as transpiration and respiration lead ultimately to water loss and senescence of the product. Fruits and vegetables are living commodities and their rate of respiration is of key importance to maintenance of quality. It has been commonly observed that the greater the respiration rate of a product, the shorter the shelf-life. The principal problem for fresh-cut fruit industries is the relative shorter shelf-life of minimally processed fruit (MPF) compared to intact product. This fact is strictly connected with the higher ethylene production of fruit tissue stimulated during fresh-cut processing (peeling, cutting, dipping). 1-Methylcyclopropene (1-MCP) is an inhibitor of ethylene action and several researches have shown its effectiveness on the inhibition of ripening and senescence incidence for intact fruit and consequently on their shelf-life extension. More recently 1-MCP treatment has been tested also for shelf-life extension of MPF but discordant results have been obtained. Considering that in some countries 1-MCP is already a commercial product registered for the use on a number of horticultural products, the main aim of this actual study was to enhance our understanding on the effects of 1-MCP treatment on the quality maintenance of whole and fresh-cut climacteric and non-climacteric fruit (apple, kiwifruit and pineapple). Concerning the effects of 1-MCP on whole fruit, was investigated the effects of a semi-commercial postharvest treatment with 1-MCP on the quality of Pink Lady apples as functions of fruit ripening stage, 1-MCP dose, storage time and also in combination with controlled atmospheres storage in order to better understand what is the relationship among these parameters and if is possible to maximize the 1-MCP treatment to meet the market/consumer needs and then in order to put in the market excellent fruit. To achieve this purpose an incomplete three-level three-factor design was adopted. During the storage were monitored several quality parameters: firmness, ripening index, ethylene and carbon dioxide production and were also performed a sensory evaluations after 6 month of storage. In this study the higher retention of firmness (at the end of storage) was achieved by applying the greatest 1-MCP concentration to fruits with the lowest maturity stage. This finding means that in these semi-commercial conditions we may considerate completely blocked the fruit softening. 1-MCP was able to delay also the ethylene and CO2 production and the maturity parameters (soluble solids content and total acidity). Only in some cases 1-MCP generate a synergistic effect with the CA storage. The results of sensory analyses indicated that, the 1-MCP treatment did not affect the sweetness and whole fruit flavour while had a little effect on the decreasing cut fruit flavour. On the contrary the treated apple was more sour, crisp, firm and juicy. The effects of some treatment (dipping and MAP) on the nutrient stability were also investigated showing that in this case study the adopted treatments did not have drastic effects on the antioxidant compounds on the contrary the dipping may enhance the total antioxidant activity by the accumulation of ascorbic acid on the apple cut surface. Results concerning the effects of 1-MCP in combination with MAP on the quality parameters behaviour of the kiwifruit were not always consistent and clear: in terms of colour maintenance, it seemed to have a synergistic effect with N2O MAP; as far as ripening index is concerned, 1-MCP had a preservative effect, but just for sample packed in air.

Use of essential oils and biocontrol cultures for the improvement of shelf-life of fresh cut products

The demand of minimally processed fruits and vegetables has increased in the last years. However, their intrinsic characteristics may favor the growth of pathogens and spoilage microbiota. The negative effects on human health reported for some traditional chemical sanitizers have justified the search for substitutes to guarantee food safety and quality. In this work we have evaluate the potential of some essential oils and their components to improve the safety and the shelf life of Lamb’s lettuce (Valerianella locusta) and apples (Golden delicious). Moreover, the effects of selected lactic acid bacteria alone or in combination with essential oils or their components, on the shelf-life and safety as well as organoleptic properties of minimally processed products, were evaluated. Since the lack of knowledge of microbial cell targets of essential oils represent one of the most important limit to the use of these molecules at industrial level, another aim of this thesis was the study of the action mechanisms of essential oils and their components. The results obtained showed the beneficial effects of the natural antimicrobials as well as the selected lactic acid bacteria on minimally processed fruit and vegetable safety and shelf-life, without detrimental effects on the quality parameters. The beneficial effects obtained by the use of the selected biocontrol agents were further increased combining them with selected natural antimicrobials. The natural antimicrobial employed induced noticeable modifications of membrane fatty acid profiles and volatile compounds produced by microbial cells during the growth. The modification of the expression in genes involved in fatty acid biosynthesis suggesting that the cytoplasmic membrane of microbial cells is one of the major cellular target of essential oils and their components. The comprehension of microbial stress response mechanisms can contribute to the scaling up of natural antimicrobials and bio-control agents at industrial level.