The environment temperature and its effect on the temperature of silage is very important for the fermentation and subsequent quality of a silage. Obligate heterofermentative lactic acid bacteria (LAB) inocula, because of their ability to inhibit yeasts, have been developed to prevent the aerobic deterioration of silages. The temperature during silage conservation may also play an important role in the fermentation profile of silages. This study has evaluated the effect of temperature, during the conservation of whole crop corn silage, untreated or treated with different LAB inocula, on the fermentation profile and on the aerobic stability of the silage. Corn was harvested at 42% dry matter and either not treated (control) or treated with Lactobacillus buchneri NCIMB 40788 (LB) at 300,000 cfu/g fresh matter (FM); Lactobacillus hilgardii CNCM I-4785 at 150,000 cfu/g FM (LH 150 ); L. hilgardii CNCM I-4785 at 300,000 cfu/g FM (LH 300 ); or LB+LH at 150,000 cfu/g FM each. In an attempt to experimentally simulate temperature fluctuations in the mass or at the periphery of a silage bunker, corn was conserved in laboratory silos at a constant temperature (20 ± 1°C; MASS) or at lower and variable outdoor temperatures (PERIPH; ranging from 0.5 to 19°C), and the silos were opened after 15, 30, and 100 d of conservation. Lactic acid, acetic acid, and ethanol contents increased in all the silages over the conservation period. The lactic acid content was higher (+10%) in the silages kept at a constant temperature than those conserved at the lower and variable outdoor temperatures. The acetic acid was higher in the treated silages than in the control ones conserved at a constant temperature for 100 d. Moreover, 1,2-propanediol was only detected in the treated silages after at least 30 d at a constant temperature, whereas only traces were detected in the LB+LH treatment for the other temperature conditions. The yeast count decreased during conservation at a slower rate in PERIPH than in MASS and on average reached 2.96 and 4.71 log cfu/g for MASS and PERIPH, respectively, after 100 d of conservation. The highest aerobic stability values were observed for LH 300 (191 h) in the MASS silage after 100 d of conservation, whereas the highest aerobic stability was observed in LB+LH (150 h) in the PERIPH silages. After 7 d of air exposure, a pH higher than 4.5 and a higher yeast than 8.0 log cfu/g were detected in all the silages opened after 15 and 30 d of conservation. A pH value close to that of silo opening was detected in the LB, LH 150 , and LH 300 silages conserved under MASS conditions after 100 d, whereas LB+LH was the most effective under PERIPH conditions. The temperature and its fluctuation during conservation of silage in laboratory silos influenced the fermentation, which in turn had an effect on the quality of silage and on the extent of the effect of LAB inocula.

The occurrence of Paenibacillus and Clostridium spores in silage is of great concern for dairy producers because their spores can contaminate milk and damage processed milk and semi-hard cheeses. Spoiled silage is considered to be the main contamination source of the total mixed ration (TMR), feces of dairy cows, and consequently bulk tank milk via the contamination of cow teats by dirt during milking. The presence of an anaerobic and facultative anaerobic sporeformer population in different matrices (soil, corn silage, other feeds, TMR, feces, and milk) and its transmission pathway has been studied on 49 dairy farms by coupling plate count data with 16S-DNA identification. The different matrices have shown a high variability in the anaerobic and facultative anaerobic spore count, with the highest values being found in the aerobically deteriorated areas of corn silages. Clostridium tyrobutyricum, Paenibacillus macerans, and Paenibacillus thermophilus were detected in all the matrices. The TMR spore count was influenced by the amount of spoiled corn silage in the TMR and by the care taken when cleaning the spoiled silage before feed-out. Most of the farms that prevent the presence of visible moldy silage in the silo and carefully clean to remove molded spots were able to maintain their TMR spore counts below 4.0 log spores/g. When a level of 4.5 log spores/g of TMR was exceeded, the feces presented a greater contamination than 3.0 log spores/g. Moreover, the higher the number of spores in the feces was, the higher the number of spores in the milk. Most of the farms that presented a feces contamination greater than 5.0 log spores/g had a higher milk spore contamination than 1,000 spores/L. Careful animal cleaning and good milking practices have been found to be essential to maintain low levels of contamination in bulk tank milk, but it has emerged that only by coupling these practices with a correct silage management and cleaning during TMR preparation can the contamination of milk by spores be kept at a low level. It has been found that aerobically deteriorated silage has a great capacity to contaminate TMR and consequently to increase the risk of milk spore contamination, even when routine milking practices are adopted correctly.

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The objective of this study was to evaluate the impact of different mixtures of two fresh-cut baby lettuce (Lactuca sativa L. var. crispa cv. Lollo Bionda [LB] and cv. Lollo Rossa [LR]) cultivars on lettuce phytochemical composition during postharvest. Lettuces were grown in a soilless culture system with continuous flotation (FL) in a greenhouse, mixed at harvest and packaged in polypropylene bags and stored at 4 °C for 9 days (d9). Mixes were made of 100, 75, 50, 25 and 0% of LB, respectively. The results showed that the phytochemicals were preserved during storage. In specific, 25LB had the highest pigment content on d1, while 50LB and 25LB had the highest inherent quality on d1.FL led to a reduced microbial contamination, thus, limiting its growth during storage. The results have revealed that high quality and microbiologically safe baby leaf vegetables (BLV), can be obtained by means of FL. The adopting a mix of lettuce cultivars could represent a positive postharvest practice to preserve the phytochemicals of BLV throughout their shelf life.

Investigating several environmental factors affecting plant growth implies having sound experimental facilities equipped to test individual factors in lab-scale although applicable later at the industrial scale. Sometimes, detailed information is hardly given in a manuscript that allows for replications by other authors, maybe due to the shortening of pages requested by journal publishers and editors. A system and methodology was developed for qualitative and quantitative analyses of baby leaf vegetables (BLV) raised in floating growing systems (FGS). Lab-scale pilot plants (LSPP) were developed in 2 greenhouses differing in structure and equipment, suitable for different growing seasons in a continental climate. The equipment and technology allowed multiple treatments and replicates for sound statistical design and data analyses. Environmental conditions and cultural techniques were studied in major and minor species (white mustard, Brassica alba L. Boiss; black mustard, Brassica nigra L. Koch; garden cress, Lepidium sativum L.; water cress, Nasturtium officinale R. Br.; rocket salad, Eruca sativa Mill.; perennial wild rocket, Diplotaxis tenuifolia L. DC.; corn salad, Valerianella olitoria L.; baby spinach, Spinacia oleracea L.) to determine best cultivation techniques in a standard soilless culture system (SCS) for BLV, based on FGS. Considering that SCS can improve raw material quality at harvest, and enhance the postharvest shelf-life of many vegetables and herbs, a standardized growing system is required to obtain premium quality raw material in terms of commercial stage, low nitrate content and long shelf-life. Among the SCS used, the FGS are suitable systems to grow leafy vegetables because the plants can grow at high densities, thereby producing high yields, and in a short time. FGS are based on sub-irrigation technology, avoiding over-head irrigation and contact between nutrient solution and edible parts, and result in greater qualitative and quantitative yields than the traditional cultivation techniques, reducing pollution, crop and substrate residues, leading to clean raw material with potential low microbiological load. The FGS is a modern technology that could be exploited more to enhance yield, quality and safety of fresh and fresh-cut BLV. The LSPP installed are providing the basis for expanding the research to other species and agronomic factors.