Inoculation with Lactobacillus plantarum of Alfalfa,Corn, Sorghum,and Wheat Silages

Alfalfa, corn, sorghum, and wheat forages were harvested for ensiling. Effects of inoculation of the forages with Lactobacillus plantarum (10⁷/g silage) were studied in small experimental 55-kg drum silos. Control and treated silages were prepared, and drums from each treatment were opened on days 1, 2, 4, 8, 16, and 33. Proximate analysis, pH, neutral detergent fiber, acid detergent fiber, soluble carbohydrate, lactic acid, and volatile fatty acid contents were measured. Total faculative anaerobic microflora were increased in all silages by addition of L. plantarum, and numbers of lactobacilli, were increased in all but corn silage. Yeasts and molds were lower only in inoculated alfalfa and wheat silages. The effect of the inoculum was observed on chemical composition only for alfalfa and wheat silages. These treated silages had a lower pH, higher lactic acid content, and great recovery of dry matter, crude protein, and detergent fiber (alfalfa) and nitrogen-free extract (wheat). Inoculation has an effect on microflora in all silages and a positive beneficial effect on nutrient recovery in alfalfa and wheat silages.     

Aerobic deterioration of lucerne (Medicago sativa) and maize (Zea mais) silages—effects of fermentation products

Eleven laboratory lucerne silages, ten farm-scale lucerne silages and one maize silage were analysed for fermentation products to determine if chemical composition could explain differences in aerobic stability. Three of the farm-scale lucerne silages and the maize silage heated within 4 days of exposure to air whereas the other lucerne silages were stable for longer than 7 days even after inoculation with a destabilising yeast inoculum. The silages were analysed for lactic acid, volatile fatty acids (C₁ to C₆), succinic acid, ethanol, and 2,3-butanediol. The concentrations of these compounds in the unstable silages were not different from levels found in stable silages on either a dry matter basis or an undissociated water basis. However, unstable silages tended to be lower in 2,3-butanediol than other silages. The time until heating in these silages was simulated using a model of aerobic fungal growth in silage. This model considered the effects of yeast and mould numbers, pH, moisture content, and lactic and acetic acid concentrations on stability. Aerobic stability in three of the four unstable silages, with and without inoculation of destabilising yeasts, was reasonably predicted by the model. Stability in the other silages was consistently underpredicted by the model. These results indicate that the stability factor found in many lucerne silages is unlikely to be one of the principal products of silage fermentation.     

Effect of moisture content on the development of carboxylic acids in traditional maize dough fermentation

Maize dough samples containing 45, 52, 65 and 80% initial moisture were fermented over a 3 day period, and the rate of development of carboxylic acids was determined. The desired volatile: non-volatile acids ratio of 0.16, titratable acidity of 2.4 mg NaOH g^?1 sample, and pH of 3.7 could be achieved with only the 52% moisture samples. A slow rate of acid production and an early onset of mould growth was observed in samples with 45% moisture. The 65 and 80% moisture samples developed high concentrations of acids with resultant high degree of sourness. Acetic, propionic and butyric acids were the major volatile acids in samples with moisture contents over 52%.     

Distribution of volatile components of grass silage

Volatile components in the steam distillates from high and low moisture cocksfoot grass silages were determined using a mass spectrometer equipped with a g.l.c. employing f.i.d. A number of volatiles appeared in the silage distillates and the gas chromatograms of both silages showed similar patterns, but the number of peaks of the volatile components for the low moisture silage was greater than that of the high moisture silage. On the other hand, a small number of volatiles were found in the fresh grass distillate and the particular volatiles differed greatly from those found in silages. The silage distillates were separated into a number of fractions, the neutral fraction appeared to be the major fraction, and there was little difference between the total yields of volatile components in both silages. Among the volatiles, i-pentanol and 4-ethyl guaiacol were the major components in both silages, but cis-3-hexenal, p-cymene, δ-cadinene and ethyl oleate were found only in the low moisture silage.     

Effect of lactic acid bacteria inoculant and beet pulp addition on fermentation characteristics and in vitro ruminal digestion of vegetable residue silage

The objective of this study was to determine the effect of beet pulp (BP) and lactic acid bacteria (LAB) on silage fermentation quality and in vitro ruminal dry matter (DM) digestion of vegetable residues, including white cabbage, Chinese cabbage, red cabbage, and lettuce. Silage was prepared using a small-scale fermentation system, and treatments were designed as control silage without additive or with BP (30% fresh matter basis), LAB inoculant Chikuso-1 (Lactobacillus plantarum, 5 mg/kg, fresh matter basis), and BP + LAB. In vitro incubation was performed using rumen fluid mixed with McDougall's artificial saliva (at a ratio of 1:4, vol/vol) at 39°C for 6 h to determine the ruminal fermentability of the vegetable residue silages. These vegetable residues contained high levels of crude protein (20.6-22.8% of DM) and moderate levels of neutral detergent fiber (22.7-33.6% of DM). In all silages, the pH sharply decreased and lactic acid increased, and the growth of bacilli, coliform bacteria, molds, and yeasts was inhibited by the low pH at the early stage of ensiling. The silage treated with BP or LAB had a lower pH and a higher lactic acid content than the control silage. After 6 h of incubation, all silages had relatively high DM digestibility (38.6-44.9%); in particular, the LAB-inoculated silage had the highest DM digestibility and the lowest methane production. The vegetable residues had high nutritional content and high in vitro DM digestibility. Also, both the addition of a LAB inoculant and moisture adjustment with BP improved the fermentation quality of the vegetable residue silages. In addition, LAB increased DM digestibility and decreased ruminal methane production.     

Aerobic deterioration of lucerne (Medicago sativa) and Maize (zea mais) Silages—Effects of Yeasts

Lucerne (Medicago sativa L) silages made in test tube silos at various dry matter (DM) levels (290-537 g kg^?1) with and without addition of glucose (20 g kg^?1 herbage) at ensiling were stable during 7 days of aerobic exposure. Lucerne silages taken from seven farm silos were similarly stable while three others were unstable (average DM loss of 62 g kg^?1 DM and pH increase from 4.35 to 7.58 in 7 days). Under similar circumstances, maize (Zea mais L) silage had a high DM loss (164 g kg^?1 DM) and an increase in pH from 3.94 to 8.13. Silages were inoculated with yeast (1 × 10⁶ CFU g^?1 silage) isolated from aerobically deteriorating farm-scale lucerne and maize silages. The stable lucerne silages were not destabilised by inoculation, but the instability of unstable lucerne silages was increased. Aerobically unstable maize silage and stable lucerne silage were inoculated and studied separately or as a 50:50 mixture. There was a distinct lag in the development of aerobic instability in the mixture compared with maize silage alone. In another experiment, the growth of the inoculum in malt agar (pH 3.5) as affected by the presence of fresh and ensiled lucerne (six cultivars), birdsfoot trefoil (Lotus corniculatus L) and red clover (Trifolium pratense L) was studied. The legume herbages did not inhibit yeast growth whereas the corresponding silages did. Five aerobically stable lucerne silages inhibited yeast development in the media whereas unstable maize silage did not. It is concluded that aerobic stability was not related to silage DM, pH, yeast numbers or glucose addition at ensiling. Stability appeared to be due to the presence of an inhibitor (or inhibitors) produced during ensilage.     

Control of Escherichia coli O157:H7 in corn silage with or without various inoculants: Efficacy and mode of action

This study aimed to evaluate the effectiveness of 3 commercial bacterial inoculants at controlling Escherichia coli O157:H7 in corn silages during ensiling and feedout phases of silage production. A second objective was to determine whether the inoculants exhibited and transferred antibacterial activity against E. coli O157:H7 to the silages. Chopped corn forage was ensiled after treatment with the following: distilled water (control); 5 × 10⁵ cfu/g of E. coli O157:H7 (EC); EC and 1 × 10⁶ cfu/g of Pediococcus pentosaceus and Propionibacterium freudenreichii (EC+BII); EC and 1 × 10⁶ cfu/g of Lactobacillus buchneri (EC+LB); and EC and 1 × 10⁶ cfu/g of L. buchneri and P. pentosaceus (EC+B500). Each treatment was ensiled in triplicate in mini silos for 3, 7, 31, and 82 d and analyzed for pH and E. coli O157:H7 counts. Samples from d 82 were also analyzed for volatile fatty acids, lactate, and aerobic stability. Antibacterial activity of inoculants and silages was determined by the Kirby-Bauer disc diffusion test. The pH of silages from all treatments decreased below 4 within 3 d of ensiling and remained low until d 82. Therefore, E. coli O157:H7 was not detected in silages after any of the ensiling durations. Applying inoculants containing L. buchneri resulted in less lactate, more acetate, and greater aerobic stability compared with the control. Applying EC+BII containing P. freudenreichii did not increase propionate or aerobic stability. Subsamples of d 82 silages were reinoculated with 1 × 10⁵ cfu/g of E. coli O157:H7 either immediately after silo opening on d 82 or after 144 h of aerobic exposure (d 88), and E. coli were enumerated 24 h later. All silages reinoculated with the pathogen on d 82 had similar, low pH values (<4) and no E. coli were detected 24 h later. Control, EC, and EC+BII silages reinoculated with the pathogen after 144 h of aerobic exposure had relatively greater pH values (4.71, 5.67, and 6.03, respectively) and E. coli counts (2.87, 6.73, and 6.87 log cfu/g, respectively) 24 h later, whereas those treated with L. buchneri had low pH values (<4) and undetectable (EC+B500) or 10-fold lower (1.97, cfu/g; EC+LB) E. coli counts. All pure cultures of commercial bacterial inoculants exhibited antibacterial activity independent of pH against E. coli O157:H7, but the pH-independent activity did not persist in the treated silages, suggesting that E. coli elimination from silages was mediated by pH reduction.     

Fermentation acids, aerobic fungal growth, and intake of napiergrass ensiled with nonfiber carbohydrates

This study evaluated fermentation characteristics and fungal numbers of napiergrass silages prepared with and without added raw or heated corn meal (10%, fresh-weight basis) at ensiling. Corn was added to napiergrass so that the silage would contain concentrate similar to that of corn silage with minimum grain content. The silages treated with raw or heated corn were fed to dairy does to compare voluntary silage consumption. After 8 wk of fermentation, pH for silage treated with heated corn was lowest, and that for napiergrass ensiled alone was highest among the treatments. The addition of corn increased lactic acid, but propionic and butyric acids were also elevated. Acetic acid decreased in response to the supplementation of corn but remained the dominant acid for all silages. Numbers of fungi (yeasts plus molds) in silages did not differ significantly at silo opening or after 24 h of exposure to air. However, the numbers of fungi at 48 h in aerated silages containing corn were lower than were the fungi counts in the control silage. When the silages were offered free choice along with concentrate at a fixed rate, dairy does tended to consume more silage treated with heated corn than raw corn. Whole-tract nutrient digestibility and serum glucose and urea N were not altered. These results indicate that the addition of either raw or heated corn meal to napiergrass at ensiling was beneficial to silage fermentation quality because it decreased pH, increased lactic acid, and apparently suppressed fungal populations via elevated antifungal acids. A further advantage of heated corn vs. raw corn was increased silage intake.     

Effects of extraction and reconstitution of ryegrass juice on fermentation,digestion and in situ degradation of pressed cake silage

Primary growth of Italian ryegrass was fractionated into green juice and pressed cake (PC). PC was ensiled either directly or after reconstitution with the juice which was spray dried and then added to water before ensiling (RPC). This process was aimed at distinguishing between chemical (removal of nutrients) and physical (mechanical disintegration) effects of fractionation. Two additional wilted silages were prepared from long cut or chopped Italian ryegrass (WL and WC, respectively). The fermentative quality, digestion and in situ degradation of dry matter for the four silages were compared. WC, RPC and PC silages indicated lactate-rich fermentation while WL silage had a comparatively low lactate content. PC silage had a lower (P<0·05) pH value with lower (P<0·05) amounts of organic acids compared with WC and RPC silage, suggesting that removal of buffering components with the juice had greater effects than shredding on fermentation of PC silage. The digestibility of protein was lower (P<0·05) in PC than WL silage but the reduction was compensated for in RPC silage. Ruminal concentrations of total volatile fatty acids were the highest (P<0·05) when goats fed WL silage while those on the other silages had similar concentrations. Ruminal pH was lower (P<0·05) in goats fed PC than WC silage and the difference was not fully reversed by reconstituting the juice to PC. Juice extraction decreased (P<0·05) the soluble fraction and the rate of disappearance of dry matter in the rumen but the potential degradability was not different among treatments. These results suggest that both chemical and physical changes due to the fractionation affect the characteristics of digestion of PC silage while the removal of nutrients has a major role in the modified silage fermentation. © 1997 SCI.     

Changes in composition of lipids,free amino acids and organic acids in rice-bran-fermented- sardine (Etrumeus teres) during processing and subsequent storage

Changes in composition of lipids, free amino acids and organic acids in rice-bran-fermented sardine—one of the traditional marine products of Japan—were investigated. The moisture content decreased rapidly during pre-curing and then slowly during rice bran fermentation. The salt content of the finished product was about 234 g kg⁻¹ on a dry weight basis. The pH decreased from 6.1 in the raw sardine to 5.3 in the finished product. Total volatile basic nitrogen increased up to 1.0 g kg⁻¹ after 2 months of rice bran fermentation and then remained almost unchanged. Most free amino acids except histidine and taurine increased during rice bran fermentation. The histamine content increased to 0.75 g kg⁻¹ at 2 months of rice bran fermentation and subsequently decreased gradually. Certain polyamines also accumulated on relatively lower levels. Lactic acid (8.14 g kg⁻¹ at 2 months of rice bran fermentation) was a prominent organic acid produced during processing. Considerable decompositions of triglyceride and phospholipids occurred accompanied by production and accumulation of a correspondingly high concentration of free fatty acids. The peroxide value and the amount of thiobarbituric acid reactive substances in the extracted total lipids decreased gradually during rice bran fermentation. It was concluded that lipid oxidation was restricted during rice bran fermentation although remarkable proteolysis occurred. The present traditional manufacturing process seems to be applicable to the technology of processing and subsequent preservation of fish products in the developing countries.     

The passage of lactic acid bacteria from silage into rumen fluid, in vitro studies

Inoculated silages sometimes improve cattle performance, possibly because of probiotic effects of lactic acid bacteria (LAB) silage inoculants. The cause of improved animal performance following feeding with inoculated silage is unclear. One issue in studying this phenomenon is to find out whether LAB pass from silage into the rumen fluid and survive in it. The purpose of the present study was to determine whether LAB from inoculated and uninoculated silages pass into the rumen fluid in vitro. Wheat and corn silages, uninoculated or inoculated with 1 of 10 commercial silage inoculant LAB, were prepared in glass jars. After ensiling, a 2.5-g silage sample was added to 25 mL of heat-sterilized or strained rumen fluid together with 5 g/L glucose, and incubated for 48 h at 39 degrees C. Analysis of the incubated rumen fluid included pH measurement, enumeration of LAB, and determination of lactic acid and volatile fatty acids (VFA). The pH of the rumen fluid decreased during incubation; both heat-sterilized and strained rumen fluid contained large numbers of LAB. The heat-sterilized rumen fluid contained lactic acid in addition to VFA, whereas the strained rumen fluid contained only VFA. The results indicate that LAB pass from silage samples into the rumen fluid in vitro and survive there. Their interactions with rumen microorganisms should be studied further to understand how some silage inoculant LAB exhibit probiotic effects in dairy cattle.     

EFFECTS OF INITIAL pH ON COMPOSITIONAL CHANGES AND SENSORY TRAITS OF FRENCH DRY-CURED HAMS

Fifty hams were distributed into 2 groups differing in initial pH of the Adductor muscle — one group with a pH < 6.1 (low pH group) and the other group with a pH of 6.1 or higher (high pH group). Ten hams were used for fresh meat analysis, while the 40 other hams were processed by dry-curing. Five hams of each pH group were used for chemical analysis before processing (day 0) and at days 74, 81, 179 and 273 of processing. The Biceps femoris muscle was analyzed for moisture, salt content, lipids, nitrogen fractions and volatile compounds. Sensory analysis was performed at days 179 and 273. The low pH hams had higher moisture and salt content at the beginning of processing. They reflected more active lipolysis and proteolysis as indicated by higher levels of free fatty acids and nonprotein nitrogen. Also, they were scored as firmer, dryer and had a less intense fat aroma.     

Fate of Escherichia coli O157:H7 and bacterial diversity in corn silage contaminated with the pathogen and treated with chemical or microbial additives

Inhibiting the growth of Escherichia coli O157:H7 (EC) in feeds may prevent the transmission or cycling of the pathogen on farms. The first objective of this study was to examine if addition of propionic acid or microbial inoculants would inhibit the growth of EC during ensiling, at silo opening, or after aerobic exposure. The second objective was to examine how additives affected the bacterial community composition in corn silage. Corn forage was harvested at approximately 35% dry matter, chopped to a theoretical length of cut of 10 mm, and ensiled after treatment with one of the following: (1) distilled water (control); (2) 1 × 10⁵ cfu/g of EC (ECCH); (3) EC and 1 × 10⁶ cfu/g of Lactobacillus plantarum (ECLP); (4) EC and 1 × 10⁶ cfu/g of Lactobacillus buchneri (ECLB); and (5) EC and 2.2 g/kg (fresh weight basis) of propionic acid, containing 99.5% of the acid (ECA). Each treatment was ensiled in quadruplicate in laboratory silos for 0, 3, 7, and 120 d and analyzed for EC, pH, and organic acids. Samples from d 0 and 120 were also analyzed for chemical composition. Furthermore, samples from d 120 were analyzed for ammonia N, yeasts and molds, lactic acid bacteria, bacterial community composition, and aerobic stability. The pH of silages from all treatments decreased below 4 within 3 d of ensiling. Escherichia coli O157:H7 counts were below the detection limit in all silages after 7 d of ensiling. Treatment with L. buchneri and propionic acid resulted in fewer yeasts and greater aerobic stability compared with control, ECCH, and ECLP silages. Compared with the control, the diversity analysis revealed a less diverse bacterial community in the ECLP silage and greater abundance of Lactobacillus in the ECLP and ECA silages. The ECLB silage also contained greater abundance of Acinetobacter and Weissella than other silages. Subsamples of silages were reinoculated with 5 × 10⁵ cfu/g of EC either immediately after silo opening or after 168 h of aerobic exposure, and EC were enumerated after 6 or 24 h, respectively. All silages reinoculated with EC immediately after silo opening (120 h) had similar low pH values (<4.0) and EC counts were below the detection limit. The ECCH and ECLP silages reinoculated with EC after 168 h of aerobic exposure had relatively high pH values (>5.0) and EC counts (5.39 and 5.30 log cfu/g, respectively) 24 h later. However, those treated with L. buchneri or propionic acid had lower pH values (4.24 or 3.96, respectively) and lower EC counts (1.32 log cfu/g or none, respectively). During ensiling, EC was eliminated from all silages at pH below 4.0. During aerobic exposure, the growth of EC was reduced or prevented in silages that had been treated with L. buchneri or propionic acid at ensiling, respectively.     

PRESERVATION OF BLUE-JACK MACKEREL (TRACHURUS PICTURATUS BOWDICH) SILAGE BY CHEMICAL AND FERMENTATIVE ACIDIFICATION

We compared acidified and lactic acid fermented silage approaches for the preservation of blue‐jack mackerel. Silages acidified with formic and propionic acids had stable pH (3.8) and low (19 mg/g N) levels of volatile nitrogen compounds (total volatile basic nitrogen, TVBN), but relatively high (82 g/100 g) final non‐protein‐nitrogen (NPN) values. The silage was fermented with Lactobacillus plantarum LU853, a homofermentative lactic acid bacterium with a high growth (0.51/h) and acidification rate at 37C (optimum temperature), able to grow in the presence of 40 g/L NaCl and to ferment sucrose and lactose. The silages at 37C reached safe pH < 4.5 values within 48–72 h, either (F2a) or not (F0), in combination with 20 g/kg salt addition; F2a acidified more rapidly, which may be an advantage for its microbiological stability. Proteolysis resulting in 53–59 g NPN/100 g N was lower in fermented than in acidified silages; however, in fermented silages, the levels of TVBN were much higher (50–80 mg TVBN/g N) than generally considered acceptable.     

Nutritive value of potato processing wastes in total mixed rations for dairy cattle

The nutritive value of wet potato processing waste for dairy cattle was determined in two experiments. In Experiment 1, rations contained, on a dry matter basis, 0, 10, 15, and 20% potato waste and were substituted for high moisture corn in diets for 32 lactating Holstein cows for 12 wk. Substituting potato waste for corn did not significantly affect milk yield, milk composition, milk production persistency, or dry matter intake. Cows fed 20% potato waste tended to decrease in milk fat percent and to shift molar proportions of rumen volatile fatty acids toward a decrease in acetate: propionate ratio. In Experiment 2, six steers were used in a 3 X 3 Latin square design to test digestibility and nitrogen utilization of potato waste substituted for high moisture corn at 0, 10, and 20% of the ration dry matter. A second group of four steers with rumen fistulas were used in a 4 X 4 Latin square to test rumen fermentation parameters. Diets contained 0, 10, 20, and 30% potato wastes and were similar to Experiment 1. Potato waste did not significantly affect digestibility of crude protein or dry matter, but at 20% substitution digestibility of acid detergent fiber decreased. Rumen ammonia, acetate, acetate to propionate ratios, and total volatile fatty acids were lower at high intakes of potato waste and pH was increased. The shift in rumen fermentation when large amounts of potatoes were fed explains the depressed butter fat on these rations.     

Effect of fermentation and bacterial inoculation on lucerne cell walls

Changes were found in the cell wall composition of lucerne after ensiling at three different dry matter (DM) contents. The amount of protein associated with cell walls was reduced during ensiling, regardless of inoculation level, by 46–68%, whereas protein associated with the lignin residue was reduced to a lesser extent (< 40%). The effect ofensiling on individual sugars of the cell wall varied. Uronics of the cell wall were decreased by 12% with wilted silages (290 g DM kg^–1) but were unchanged in a higher dry matter silage (401 g DM kg^–1) and silages with a limited pH change during ensilage. The arabinose and galactose contents, as a fraction of cell walls, decreased (15–24%), increasing glucose and xylose contents proportionally. Inoculation decreased arabinose and galactose contents early in the fermentation when the pH decline was enhanced but final values were not significantly different (P > 0.32). Removal of the sugars from the cell wall appears to be related to pH because silages with little pH change had no change in the cell wall sugars and inoculation reduced the cell wall sugars only after silage pH declined.     

Effect of the stage of growth,wilting and inoculation in field pea (Pisum sativum L.) silages. I. Herbage composition and silage fermentation

The stage of growth, field wilting and inoculation with lactic acid bacteria (LAB) effects were studied by ensiling herbage of field pea (Pisum sativum L.) at four consecutive stages. Stands of semi‐leafless field pea, sown in spring, were harvested at four progressive morphological stages (end of flowering, I; beginning of pod filling, II; advanced pod filling, III; beginning of ripening, IV). For each stage of growth, the herbage was field wilted to a dry matter (DM) content of 318, 300, 348 and 360 g kg^?1 for stages I, II, III and IV, respectively. The unwilted and wilted herbages were ensiled in 5‐L silos, with (I) and without (C) a LAB inoculant (Lactobacillus plantarum). High levels of ethanol, lactic acid and volatile fatty acids (VFA) were observed in all silages, facilitated by the high levels of water‐soluble carbohydrates (WSC) at ensiling (from 111 to 198 g kg^?1 DM). Despite the low pH values (4.3 and 4.1 for C and I silages, respectively), all the silages showed detectable levels of butyric acid. Field peas can be successfully ensiled after a short wilting period with reduced field curing and reduce DM losses onward from advanced pod filling stage, with the aid of LAB inoculum. Copyright © 2006 Society of Chemical Industry     

卵形鲳鲹肌肉原料特性及食用品质的分析与评价

为探究卵形鲳鲹肌肉的原料特性及食用品质,对卵形鲳鲹的形体参数、各部分质量分数及采肉率、肌原纤维直径、质构、色泽、蒸煮损失率、滴水损失率、失水率、pH值、基本成分质量分数、蛋白质组成、矿物质元素含量、脂肪酸组成、氨基酸含量及挥发性风味物质比例等多方面指标进行测定和分析。结果表明：卵形鲳鲹肥满度高但采肉率低,加工下脚料多;其肌原纤维直径为（77.84±4.94）μm,肉质细嫩;腹部肌肉的白度最高,硬度和咀嚼性明显高于背部和尾部,更适合加工为即食鱼片;卵形鲳鲹肌肉的水分和粗脂肪质量分数分别为（71.65±0.55）%、（8.74±0.55）%;肌肉中钠、镁含量相对其他鱼类略高,饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸比例接近1∶1∶1,必需氨基酸指数为93.51,己醛、壬醛、2-乙基己醇为其主要挥发性风味物质。本研究可为卵形鲳鲹的多元化加工利用提供基础数据和参考。     

Effect of treatment with a mixture of bacteria and fibrolytic enzymes on the quality and safety of corn silage infested with different levels of rust

This project aimed to determine if a dual-purpose bacterial inoculant could mitigate potential adverse effects of increasing levels of rust infestation on the quality, aerobic stability, and safety of corn silage. Corn plants with no rust infestation (NR), or medium (all leaves on the lower half of the plant affected, MR), or high (all leaves affected, HR) levels of southern rust infestation were harvested at random locations on a field, chopped, and ensiled without (control, CON) or with a dual-purpose inoculant applied at a rate that supplied 1×10(5)cfu/g of Pediococcus pentosaceus 12455 and 4×10(5)cfu/g of Lactobacillus buchneri 40788. Each treatment was prepared in quadruplicate in 20-L mini silos and ensiled for 97 d. As the level of rust infestation increased, the concentrations of dry matter (DM) and neutral detergent fiber increased, whereas DM digestibility decreased by up to 16%. Control HR silages also had lower 24-h neutral detergent fiber digestibility (NDFD; 36.2% of DM) than CON MR (39.8%) or NR silages (38.1%). Inoculation increased the NDFD of NR (43.4%) and MR silages (45.7%) but not HR silages (33.0%). Concentrations of lactate and volatile fatty acids decreased with increasing rust infestation in CON silages, but this trend was absent in inoculated silages. In HR silages, inoculation increased aerobic stability by 75% (77.3 vs. 44h), and prevented production of aflatoxin (5.2 vs. 0mg/kg). The concentration of aflatoxin in uninoculated HR silages exceeded action levels stipulated by the US Food and Drug Administration. In conclusion, increasing rust infestation was associated with reductions in the nutritive value and fermentation of corn silage. Inoculation reduced adverse effects of rust infestation on the fermentation, increased 24-h NDFD of NR and MR silages, and decreased aerobic spoilage and aflatoxin production in HR silages.     

不同干制方式对蓝点马鲛脂肪氧化和挥发性风味成分的影响

为探究不同干制方式对水产品脂肪氧化与挥发性风味物质组成的影响,以蓝点马鲛（Scomberomorus niphonius）为原料,采用热风干制、冷风干制和传统自然晾晒法制得对应实验组样品。测定了原料和不同实验组样品的水分质量分数、pH、脂肪含量、酸价（Acid value,AV）、过氧化值（Peroxide value,POV）、丙二醛（Malondialdehyde,MDA）、脂肪酸组成和挥发性风味物质等指标。结果显示:三种干制方式制得的样品的水分质量分数均在30%左右;pH始终保持在6以上;冷风干制组的AV、POV和MDA含量整体较低（P<0.05）;热风干制组中脂肪含量下降最多,AV含量最高,POV和MDA含量显著低于自然晾晒组（P<0.05）;自然晾晒组中AV含量最低,POV和MDA含量显著高于其他组别（P<0.05）。干制样品中不饱和脂肪酸尤其是ω-3多不饱和脂肪酸含量下降显著（P<0.05）,其中自然晾晒组下降最为明显。原料和干制样品中共检出了8大类120种挥发性风味成分,主要由醛类、醇类和酯类构成。经主成分分析3个主成分对风味的累计贡献率达99.9%,其中自然晾晒组的总体评分最高。结果表明干制方式对蓝点马鲛的脂肪氧化程度和风味均有较大的影响,其中自然晾晒组风味更佳。本研究为传统的水产品加工行业的技术转型提供有效的数据支撑和发展方向。