Die regelmäßige Reinigung von Maschinen und Anlagenteilen ist integraler Bestandteil der Lebensmittel-, Pharma-, Kosmetik- und Chemieproduktion. Gesetzliche Hygienestandards gewährleisten dabei ein einheitlich hohes Qualitätsniveau. Nun lässt sich vor allem in der Lebensmittelherstellung eine Entwicklung zu zunehmend verschärften Hygienebestimmungen beobachten. Die Gründe hierfür liegen einerseits im wachsenden Markt für naturbelassene Lebensmittel mit verlängerter Haltbarkeit sowie andererseits im Trend zur flexiblen Produktion in kleineren Chargen, d.h. mehr Reinigungszyklen pro Tag oder Woche. Dadurch gewinnt auch die messbare Gewährleistung von Hygienestandards weiter an Relevanz. Aufgrund steigender Effizienzerwartungen in der Lebensmittelverarbeitung besteht demgegenüber ein erheblicher Bedarf, die Reinigungszeiten zu verkürzen, um die Zykluszeiten zu verkürzen (z.B. bei der Reinigung von Einzelteilen) und so die Maschinenverfügbarkeit zu erhöhen. [...aus dem Text]

A room with many well-preserved artifacts was excavated at Tell Halif in a level associated with Ancient Judah. By using analogy the use of these artifacts can be compared with that of other similar objects. Analogy is at the heart of archaeological interpretation and allows a more explicit determination of the possible uses of artifacts and their patterning. The artifacts serve as evidence for reconstructing life in and around an archaeologically excavated space. By discerning the patterns of artifact distribution we can interpret how the space might have been used. The room excavated at Tell Halif has strong evidence for food processing, closely integrated with storage. Textile production was also carried out in the room. Other artifacts point to food consumption, play, personal ornamentation and the use of symbolic images. The patterning of the artifacts indicates a busy multi-use space.

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Plant-derived protein such as pea protein is a promising replacement for animal protein and is becoming popular in recent years because of its high nutritional value and potential reduction of environmental footprint. However, the increasing demand for plant-derived proteins is accompanied by the increase of wastes during protein processing such as wastewater containing dilute protein content, which may raise the cost for the downstream processing. Therefore, there is an emerging need to develop novel processing strategies to reduce waste while valorizing useful ingredients. Several researchers suggest that foam fractionation technology can be a viable approach to extract and concentrate protein from dilute wastewater effluent. This technology has already been applied to the chemical and food industry for the extraction of surfactant and animal proteins from wastewater. To design and apply foam fractionation to the plant-derived protein industry, fundamental knowledge on foaming properties of dilute plant-derived protein solution is needed and is currently lacking. Therefore, the objective of this thesis is to advance a fundamental understanding of the foaming properties of dilute pea protein solutions (protein concentration ≤ 1wt%). To achieve the objective, a multiscale approach is used, which is comprised of a detailed investigation of both bulk and interfacial properties of pea protein solutions and foaming properties such as foaming capacity and stability with the help of bubble structure and foam volume kinetics. The focus of this thesis is on the effect of protein concentration. Results demonstrate that protein adsorption kinetics can be characterized by four distinctive regimes: lag phase, diffusion-limited regime, transitional regime, and conformation change regime, which are highly dependent on the protein concentration. However, apparent viscosity is less affected by the protein concentration. Results also show that depending on the protein concentration, two regimes can be distinguished for foam capacity and foam stability. For the first time, these regimes can be rationalized by contrasting characteristics times of protein adsorption kinetics and processing time scale – residence time of bubbles during the foam formation. New findings from this fundamental research will shed light on the control and optimization of foaming properties of plant-derived protein solutions for applications ranging from food processing design to food product development.

Consumption of prepared foods is increasing dramatically. A more harried lifestyle, the changing role of women --and men, the advancement of household appliances, and improvements in food processing technology have all played significant roles in this increase. This study identifies prepared food users and non-users and compares their psychographic and demographic profiles. Study results are presented and implications drawn from the results are discussed.

The purpose of this study was to determine the impact of key process parameters on the flow properties of a novel High Protein Dairy Food (HPDF). HPDF was manufactured by an approach similar to that of manufacture of Halloumi cheese (a semi hard cheese originally from Cyprus). The effect of pasteurization condition, pH of acidification and homogenization were investigated on flowability, composition and texture of the HPDF. The study consisted of three different stages. After each stage of experimentation, the HPDF was analyzed for compositional, textural (by texture profile analysis) and flow properties during heating by microwave, oven and hot water was measured by Schreiber melt test. The first stage of experimentation screened 18 batches of HPDF under three levels of pasteurization conditions (191°F/16 sec, 175°F/16 sec and 161°F/16 sec), three levels of pH of acidification (5.8,6.2 and 6.6) and two levels of homogenization conditions (two stage homogenization (2000 psi/500 psi) and no homogenization). Based on the results of the first stage, a statistically powerful second stage of experiment was designed in which two levels of pasteurization condition (191°F/16 sec and 161°F/16 sec) and three levels of pH of acidification (5.8, 6.2 and 6.6) were employed in duplicate to manufacture HPDF. The third stage of experimental design was to investigate the effect of two-stage homogenization treatment (2000 psi/500 psi) with two levels (homogenization and no homogenization). The results of all three stages of experimentation proved that HPDF made from milk pasteurized under higher pasteurization condition (191°F/16 sec) had significantly higher flow resistance under all three heating conditions. There was significant interaction between pH of coagulation of milk and pasteurization condition on flow properties of HPDF with pH of coagulation 5.8 restriction flow of HPDF under all three heating conditions. The role of homogenization in restricting flow of HPDF was not significant, although the mean flow of HPDF, made from homogenized milk, decreased. The mean protein content and mean moisture content of HPDF was significantly affected by all three processing conditions, although the mean fat content of HPDF was not influenced by any of these conditions. The mean fat, protein and moisture content of HPDF were in the range of 10.5-11, 26-34 and 47-54 percent respectively. The primary textural properties affected significantly by the processing condition were hardness, chewiness and gumminess. Particularly, hardness was influenced by higher pasteurization condition and lower pH of acidification. Further, to judge the consumer acceptability of HPDF, various recipes made out of HPDF with different heating applications (baking, stir-frying and soup) were served to 12 panelists of DPTC. Their opinions were collected and analyzed statistically. The analysis of limited focus group survey showed that consumer liking for HPDF recipe was significantly influenced by prior familiarity with the recipe, although there was some preference for HPDF over tofu due to its ‘dairy’ flavor. When the texture of HPDF manufactured from milk pasteurized at 191°F/16 sec and pH of acidification 5.8 and 6.2 were compared with various commercial protein sources, the hardness of the HPDF was very close to extra firm tofu. All the other textural properties of HPDF were significantly different from firm, silken, baked or reduced fat tofu. From this project, it is evident that a high protein food, which can be part of day-to-day human diet and potential tofu alternative, can be obtained using halloumi approach by optimizing pasteurization condition (191°F/16 sec) and pH of coagulation (5.8).

String cheese, a Mozzarella cheese, has the unique ability to string in fibrous strands when pulled apart. Graders judge string cheese by its stringy texture; samples with copious amounts of string are awarded high ratings. But just as the texture of natural cheeses softens with time, the stringy texture of string cheese can diminish with age too. Age related softening in cheese is due primarily to an important biochemical event known as proteolysis, which is attributed to inherent milk proteinases, residual coagulant activity, and enzymes from the lysis of starter culture microorganisms. It is hypothesized that a post manufacture heat treatment of string cheese could inactivate these proteolytic enzymes and slow or eliminate proteolysis during storage. Therefore, the main objective of this study was to determine the effects of a post manufacture thermal dip treatment on proteolytic activity in packaged, commercial string cheese. Proteolysis was examined qualitatively by Urea-PAGE electrophoresis, quantitatively by measuring percentage of water-soluble nitrogen (%WSN), and by using a scoring method to analyze stringy texture during refrigerated storage. Fresh, commercial string cheese was sourced on two separate occasions and treated six days after manufacture. Treatment consisted of dipping the packaged cheese sticks in water baths at 55°C, 75°C, and 95°C for 30 and 60 seconds. String cheese that did not undergo treatment served as the control. Treated and control cheeses were stored at 4°C until sampling for Urea-PAGE, WSN extraction, and texture analysis on days 1, 11, 22, 29, 49, 91, and 172 after treatment. The degree of β-CN breakdown was not observed to be different between all treatment levels throughout the storage period. This was not expected since Mozzarella cheese exposed to a higher temperature should have more plasmin activity than that of cheese exposed to a lower temperature. There was a trend of slightly more intact αs1-CN in the most severely treated string cheese (95°C for 60s) when compared to the control at the final time point of the study. This suggests the possibility of successful inactivation of residual coagulant, intracellular enzymes, or other proteolytic enzymes in the string cheese at this treatment. However, only storage time had a significant effect on %WSN (p The research completed in this study provides insight of the proteolytic effects from a thermal treatment process applied post string cheese manufacture. Though relationships between the treatments to the extent of secondary proteolysis and stringy texture were not significant, it was still found that there was more intact αs1-CN due to one of the treatments. These results suggest that it is possible that the use of other heat treatment parameters, longer storage period, or a combination of the two could show a significant relationship between thermal treatment and proteolysis. These results also suggest that further work to improve shelf life of string cheese or other cheese varieties through the concept of a post manufacture heat treatment may be promising.

Blueberry juice and pomace, enzyme pretreated (PT) or not, were extracted (EM) by steam and hot press methods. The pomace was further dried by convection oven (OD) or freeze-dried (FD). Juice yield was not affected by PT but was greater for steam extract (SE), due to water uptake. Carbohydrate and protein concentration were greater for hot-pressed (HP) pomace. Anthocyanins were not affected by PT or EM whereas phenolics were greater HP juice when subjected to enzymes. Dehydration method did not affect total phenolics when pomace was from HP but were higher in OD SE pomace. Enzymatic pretreatment had little influence on pomace quality, but HP pomace resulted in higher nutrients probably due to dilution. Oven drying resulted in slight degradation of pomace anthocyanins but not total phenolics. The dried pomace was shown to possess good nutrient quality and elevated functional components and can be used for value-added products.

This study examined the effects of electrical stimulation on water-soluble flavor compounds in beef semimembranosus muscle, collected immediately after exsanguination (PRE), immediately after stimulation (POST), and 24 h postmortem (H24) from both stimulated (ES) and non-stimulated (CON) carcasses. Short-chained peptides were greater in ES at H24 (P = 0.007). Glutamic acid concentration was above its taste threshold (0.044 mmol/kg) and was less in ES at PRE and POST by 0.030 mmol/kg (P ≤ 0.028) but was similar in both ES and CON by H24 (P = 0.142). Lysine, a Strecker amino acid, was greater in ES at H24 by 0.138 mmol/kg (P = 0.002). Adenosine triphosphate and adenosine 5’-monophosphate were greater in CON at both POST and H24 (P < 0.001). Inosine 5’-monophosphate was greater at H24 in CON (P < 0.001) than in ES. Electrical stimulation may negatively impact beef flavor by increasing bitter peptides and decreasing umami-enhancing nucleotides.

A contributing factor in recurrent Listeria monocytogenes (L. monocytogenes) food contamination is that this bacterium produces biofilms on surfaces to persist in food-processing environments. Quorum sensing (QS) is a cell-to-cell communication system utilized by bacteria within biofilms to collaborate and adapt to environmental stresses. However, the details of how the QS-dependent network contributes to biofilm development of L. monocytogenes have yet to be well understood. By comparing the transfer rates of planktonic and biofilm (sessile) L. monocytogenes from stainless steel blades to bologna slices, we found that sessile bacteria had reduced transferability onto a single slice but caused the increase in the number of contaminated slices. This suggests that physiological adaptions derived during biofilm development affect bacterial dissemination. Given the contribution of proteins and environmental temperatures to the extracellular polymeric substances (EPS) synthesis and biofilm integrity, we evaluated the exoproteomes of biofilms formed at 25 and 37°C using 2D-gel electrophoresis and LC-MS/MS. We found exoproteases Lmo0186, Cwh, and Spl exclusively in biofilms formed at 25°C and their greater expression in the gene level at 25°C. By using the zymography and crystal-violet-staining assay with a protease inhibitor, we observed a greater proteolytic activity at lower temperatures and showed that the attenuated proteolytic activity of proteases is positively correlated with increased biofilmorming ability at 25°C. Considering the transcriptional role of QS systems during biofilm development, we investigated how the accessory gene regulator (Agr)-based and metabolite S-Adenosylmethionine (SAM)-involved QS systems modulate nutrient availability and EPS synthesis. The results revealed that the SAM signal interacts with the Agr QS at the transcriptional level during biofilm development, whereas SAM and Agr QS regulate distinct EPS synthesis pathways. Additionally, this interaction is dependent on bacterial life modes (planktonic and sessile). Overall, we conclude that L. monocytogenes manipulates the synthesis of EPS with the coregulation of metabolism and QS for biofilm formation and the production of exoproteases for biofilm dispersion. These precise regulations on EPS enable L. monocytogenes to prolong its survival and promote its dissemination in environments.