Browsing by Subject "chilling"
Now showing items 1-4 of 4
-
(2007)Contamination routes of Listeria monocytogenes were examined in a chilled food processing plant that produced ready-to-eat and ready-to-reheat meals during an 8-year period by amplified fragment length polymorphism (AFLP) analysis. A total of 319 L. monocytogenes isolates were recovered from raw materials (n=18), the environment (n=77), equipment (n=193), and products (n=31), and 18 different AFLP types were identified, five of which were repeatedly found to be persistent types. The three compartments (I to III) of the plant showed markedly different contamination statuses. Compartment I, which produced cooked meals, was heavily contaminated with three persistent AFLP types. AFLP type A1 dominated, and it comprised 93% of the isolates of the compartment. Compartment II, which produced uncooked chilled food, was contaminated with four persistent and five nonpersistent AFLP types. The equipment of compartment III, which produced cooked ready-to-reheat meals, was free of contamination. In compartments that produced cooked meals, the cleaning routines, product types, and lack of compartmentalization seemed to predispose production lines to persistent contamination. The most contaminated lines harbored L. monocytogenes in coolers, conveyors, and packing machines. Good compartmentalization limited the flow of L. monocytogenes into the postheat -treatment area and prevented the undesired movement of equipment and personnel, thus protecting the production lines from contamination. In compartment II, grated cheese was shown to cause product contamination. Therefore, special attention should be paid to continuous quality control of raw ingredients when uncooked ready-to-eat foods are produced. In compartment II, reconstruction of the production line resulted in reduced prevalence rates of L. monocytogenes and elimination of two persistent AFLP types.
-
(2020)Bud dormancy of plants has traditionally been explained either by physiological growth arresting conditions in the bud or by unfavourable environmental conditions, such as non-growth-promoting low air temperatures. This conceptual dichotomy has provided the framework also for developing process-based plant phenology models. Here, we propose a novel model that in addition to covering the classical dichotomy as a special case also allows the quantification of an interaction of physiological and environmental factors. According to this plant-environment interaction suggested conceptually decades ago, rather than being unambiguous, the concept of "non-growth-promoting low air temperature" depends on the dormancy status of the plant. We parameterized the model with experimental results of growth onset for seven boreal plant species and found that based on the strength of the interaction, the species can be classified into three dormancy types, only one of which represents the traditional dichotomy. We also tested the model with four species in an independent experiment. Our study suggests that interaction of environmental and physiological factors may be involved in many such phenomena that have until now been considered simply as plant traits without any considerations of effects of the environmental factors.
-
(2020)For species to stay temporally tuned to their environment, they use cues such as the accumulation of degree-days. The relationships between the timing of a phenological event in a population and its environmental cue can be described by a population-level reaction norm. Variation in reaction norms along environmental gradients may either intensify the envi- ronmental effects on timing (cogradient variation) or attenu- ate the effects (countergradient variation). To resolve spatial and seasonal variation in species’ response, we use a unique dataset of 91 taxa and 178 phenological events observed across a network of 472 monitoring sites, spread across the nations of the former Soviet Union. We show that compared to local rates of advancement of phenological events with the advancement of temperature-related cues (i.e., variation within site over years), spatial variation in reaction norms
-
(Helsingfors universitet, 2017)Blackcurrant (Ribes nigrum L.) is a woody plant in cold regions and it adapts well for the Finland’s boreal zone. There were less than 600 companies farming blackcurrant and green currant in 2014 and the acreage was 1449 ha and the level of yield was over 1000 kg/ha. In year 2016, the number of companies were 544 and the acreage was 1435 ha and the level of yield less than 1000 kg/ha. There has been a pressure to reduce the high price of domestic blackcurrant, due to that the inexpensive imported berries have been taken more position in industry. The global warming can be a serious threat for the cultivation of blackcurrant in the future. There is a need for new cultivars of blackcurrant in Finland and the objective of this research was to examine the depth and reversal of on dormancy on various points of time and the resilience of winter. For the results the bud burst was monitored in quantity and temporal on forcing. The processing of release of dormancy in various temperatures and light conditions before the forcing was also included to the research. The cold hardiness was tested in temperatures, which was descending step by step in controlled sub-zero experiment. The results demonstrated that the bud burst was the lowest during the deepest dormancy in OctoberNovember and the largest in February, when the dormancy was already released. ‘Almiai’ and ‘Gagatai’ were the best cultivars, which were able to maintain the dormancy; in first forcing in October, bud burst 0 %. The bud burst was particularly substantial in February and ‘Ben Tron’ the bud burst was even 80 %. In October-November the time elapsed for bud burst was highest and least was in February with average of 10 days. The most optimal temperature in dormancy release was 0 ⁰C. On the cultivar ‘Mikael’ the bud burst was quicken in +18 ⁰C . The longer the processing time was, the shorter was the time for bud burst. The temperatures +12 ⁰C and +18⁰C were too high for dormancy release. In cold hardiness, the cultivars didn’t differ much from each other. The results demonstrate that the cultivars differ from each other in the depth of dormancy and release. ‘Almiai’ and ‘Gagatai’ maintained best their dormancy. These cultivars could be suitable options for farming in Finland. They were also winter hardiness. In the future, there should be breeding of blackcurrant cultivars, which adjust different kind of environments. Additionally, we should discover and breed cultivars, which have good resistant for winter and maintain dormancy, even though the temperatures are varying in winter.
