Low Temperature Long Time Research Articles

Effect of Pulsed Electric Field (PEF) on Bacterial Viability and Whey Protein in the Processing of Raw Milk

There is growing concern regarding the nutritional value of processed food products. Although thermal pasteurization, used in food processing, is a safe method and is widely applied in the food industry, food products lack quality and nutritional value because of the high temperatures used during pasteurization. In this study, the effect of pulsed electric field (PEF) processing on whey protein content and bacterial viability in raw milk was evaluated by changing the PEF strength and number of pulses. For comparison, traditional pasteurization techniques, such as low-temperature long-time (LTLT), ultra-high temperature (UHT), and microfiltration (MF), were also tested for total whey protein content, bacterial activity, and coliforms. We found that, after treatment with PEF, a significant decrease in total bacterial viability of 2.43 log and coliforms of 0.9 log was achieved, although undenatured whey protein content was not affected at 4.98 mg/mL. While traditional pasteurization techniques showed total bacterial inactivation, they were detrimental for whey protein content: β-lactoglobulin was not detected using HPLC in samples treated with UHT. LTLT treatment led to a significant decrease of 75% in β-lactoglobulin concentration; β-lactoglobulin content in milk samples treated with MF was the lowest compared to LTLT and UHT pasteurization, and ~10% and 27% reduction was observed.

Effect of dairy unit operations on immunoglobulins, colour, rheology and microbiological characteristics of goat milk

Raw goat milk was processed by low-temperature long-time (LTLT) and high-temperature short-time pasteurisation, boiling, skimming, microfiltration, and concentration to 25% solids to investigate the effects on composition, rheology, immunoglobulins, lactoferrin and microbial quality. All processing interventions had significant effect on fat, protein and ash content. pH of goat milk was decreased by heating and concentration. Skimming had lesser reduction of immunoglobulin G (IgG), immunoglobulin A (IgA), and lactoferrin (LF), compared with those by microfiltration and heat treatments. Levels of IgG and lactoferrin were the lowest after LTLT pasteurisation, while IgA was the least after boiling. Skimming and microfiltration reduced L∗ values; heating increased b∗ values. Heating increased rennet gelation time and reduced coagulum strength. Microbiologically, heated and microfiltered goat milk were comparable, but the latter had reduced total bacteria and coliform counts. Heat stability maxima were at pH 6.8–7.0 for raw and heated goat milk; peak values were different.

Organoleptic quality of pasteurization milk by matoa (Pometia pinnata) leaf extract supplementation

This study was aimed to analyze the effect of adding matoa leaf extract (MLE) and different pasteurization methods (PM) on organoleptic characteristics of pasteurized milk (PMi). This study used a completely randomized design of factorial pattern 5×2 with 3 replications consisting of 2 factors, the level of matoa leaf extract and pasteurization methods. Pasteurized milk was made from reconstituted milk i.e. full cream milk powder, each sample was added by MLE with levels of 0%, 0.05%, 0.10%, 0.15% and 0.20%, then pasteurized at Low-Temperature Long Time (LTLT) (63°C for 30 minutes) and High-Temperature Short Time (HTST) (72°C for 15 seconds). The result of the study indicated that supplementation of 0.20% MLE combination by HTST method results in best Pasteurization Milk, but not favored by the panelist. The HTST pasteurization method with Pasteurization Milk was color white (did not change the natural color of milk), specific flavor, taste, and preferred by panelists.

Profiles of initial, intermediate, and advanced stages of harmful Maillard reaction products in whole-milk powders pre-treated with different heat loads during 18 months of storage

This study evaluated the chemical changes in five types of whole-milk powders (WMP) with different heating loads during storage. The WMP was preheated using low-heat [low-temperature long-time (LTLT), high-temperature short-time pasteurization (HTST)] and high-heat process [ultra-pasteurization (ESL), ultra-high-temperature (UHT) treatments, and in-bottle sterilization (BS)]. Furosine increased by 2.5–3.0 times in high-heat WMP and 5.7–8.4 times in low-heat WMP during storage. 5-(hydroxymethyl)furfural (HMF) content in high-heat WMP was on average 1.4- to 2.4-fold higher than in low-heat WMP during storage. The increases in the amount of Nε-(carboxymethyl)lysine (CML) and Nε-(carboxyethyl)lysine (CEL) in high-heat WMP were more than that in low-heat WMP (CML, 3.4–4.9 vs 3.1–3.4 times; CEL, 3.4–4.2 vs 2.7–3.0 times). Pyrraline in high-heat WMP increased by 1.8- to 2.1-fold. 2-Furaldehyde, CML, and CEL increased slowly with 12 months of storage and then accelerated. Storage time significantly contributed to more furosine, HMF, CML, and CEL contents in high-heat WMP.

Physicochemical characteristics and sensory acceptability of crackers containing red ginseng marc.

Red ginseng marc (RGM), a by-product from ginseng industry, still contains bioactive compounds such as ginsenosides and dietary fibers. The objective of this study was to investigate effects of baking conditions and formulations on physicochemical and sensory characteristics of crackers in which RGM was incorporated. The sum of ginsenoside Rb1, Rg1 and Rg3 (58.69 ± 2.93mg/100g, dry basis) and dietary fibers (7.52 ± 1.22g/100g) were the highest in the crackers baked at 120°C for 60min. The crackers with 5% replacement of wheat flour with RGM scored the highest in taste and overall acceptability. The baked crackers still contained relatively high amounts of ginsenoside Rb1 (7.62 ± 0.34mg/100g), Rg3(R) (7.51 ± 0.99mg/100g) and Rg3(S) (8.65 ± 0.77mg/100g) and dietary fiber (2.59 ± 0.17g/100g). The results suggest that low temperature-long time may be a suitable baking condition to retain bioactive ginsenosides in RGM and using proper amount of RGM in bakery products may improve not only nutritional quality but also sensory properties.

The Best Pasteurization Method in Reducing the Amount of Bacteria in Cow’s Milk on People Dairy Farm

One method to reduce the number of bacteria and kill pathogenic bacteria is pasteurization. The purpose of this study is to get the best pasteurization method to reduce the number of bacteria and meet the Indonesian national standard requirements. This research is a comparative study to compare the methods of HTST (High Temperature Short Time) and LTLT (Low Temperature Long Time) pasteurization using samples of cow’s milk from the people’s dairy farms in Sunten Jaya Village, Lembang. The results showed the average total colonies number of cow’s milk before pasteurization was1,19x104 CFU/m, post pasteurization using LTLT method was 8.8x102 CFU/ml, and HTST method was 3.2x102CFU/ml. There was a significant decrease in the number of bacteria after pasteurization, with a p-value of 0.027 after being analyzed by the Kruskal Wallis test (p-value < 0.05).In addition, there was a significant difference between the total colonies number of HTST and LTLT post-pasteurization after being analyzed by the Mann Whitney test, with p-values = 0.05 (p-value < 00.05). Thus the HTST method is the best method in reducing the number of bacterial colonies in cow’s milk from Sunten Jaya Village, Lembang.

Effect of LTLT heat treatment on cathepsin B and L activities and denaturation of myofibrillar proteins of pork

The aim was to study biophysical and chemical changes during low-temperature long-time (LTLT) heat treatment of pork by measuring cathepsin B+L activity, surface hydrophobicity of myofibrils, particle size of myofibrils and effect on meat toughness as indicated by Allo-Kramer shear force. Longissimus thoracis et lumborum muscles were divided into large pieces, vacuum packaged and cooked in water baths at 53, 58, 63, 68 and 73 °C for 1, 8 and 24 h. The results showed that the meat toughness was markedly lower at temperatures of 53 °C and 58 °C and decreased with increasing holding time. Myofibrillar surface hydrophobicity increased with temperature, but not with time, indicating aggregation and/or gelation phenomena took place. Treatments with the lowest shear force values generally had smaller particles and were associated with high cathepsin B+L activity. A mechanism by which these cathepsins might affect the aggregation dynamics and change the mechanical properties of meat is proposed.

Physical and turbidimetric properties of cholecalciferol- and menaquinone-loaded lipid nanocarriers emulsified with polysorbate 80 and soy lecithin

The present study aimed to investigate the physical and turbidimetric properties of cholecalciferol- and menaquinone-loaded lipid nanocarriers emulsified with different ratios of polysorbate 80 and soy lecithin. The lipid nanocarriers were subjected to three different heat treatments, LTLT (low temperature long time), HTST (high temperature short time), and autoclave treatments. Both cholecalciferol and menaquinone were successfully encapsulated in lipid nanocarriers and there was little loss of them during preparation. The droplet size of lipid nanocarriers emulsified with only polysorbate 80 increased and its PDI became larger than 0.3 after autoclave treatment. Moreover, 30.9% and 49.4% of cholecalciferol and menaquinone, respectively, were lost. In turbidimetric analysis, the destabilization by creaming formation in the upper layer of the lipid nanocarriers emulsified with a high polysorbate ratio was observed. However, the use of combination of both emulsifiers inhibited destabilization by flocculation as well as retained the cholecalciferol and menaquinone after all heat treatments.

Chemical and sensory evaluation of cold brew coffees using different roasting profiles and brewing methods

This study evaluated the effects of different roasting profiles (time/temperature) and brewing methods on the physicochemical and sensory characteristics of coffee brews. Cold brewing (dripping and immersion) and hot brewing (French press) methods were studied to understand the effects of water temperature and technical brewing method conditions on the chemical compound extraction in coffees roasted at high-temperature short time (HTST) and low-temperature long time (LTLT). The results showed that coffee beverages were clearly differentiated concerning the roasting profile when hot water was used (90 ± 3 °C) in brewing. Separation of beverages according to the water temperature used in brewing was observed. Notably, hot brewing coffees were distinguished from cold brewing (19 ± 2 °C) based on a higher titratable acidity and abundance of some furan compounds. The non-volatile extraction rate increased at higher brewing temperatures. At the same brewing temperature, dripping exhibited a higher extraction rate than immersion brewing, which suggests that the coffee extraction process is affected by the design and operation of the cold brewing system. Coffee beverages brewed with HTST and cold dripping displayed the highest value in total dissolved solids (TDS), extraction yield, as well as the highest caffeine, trigonelline, 4- and 5-caffeoylquinic acids (CQAs) contents. Regardless of the roasting profile, coffees brewed by cold dripping were perceived with more bitter and roasted flavors. In contrast, cold immersion and hot coffee beverages showed remarkable sweetness, nutty, caramel, and malt attributes. In turn, these attributes showed an inverse correlation with caffeine concentration, trigonelline, CQAs, and TDS. The findings of this study demonstrate that volatile and non-volatile compounds present in roasted coffee depend on time-temperature roasting conditions; in turn, their presence in the resulting beverages are related to the extraction of the operational conditions of coffee brewing methods.

Efecto de dos métodos de pasteurización en el contenido de componentes bioactivos y capacidad antioxidante de la pulpa de nanche (Byrsonima crassifolia) y sus cinéticas de pérdida durante el almacenamiento en refrigeración

The aim of this work was to evaluate the effect of two pasteurization methods: Low Temperature Long Time (LTLT) carried out at 63 ± 2.0 °C/30 min and High Temperature Short Time (HTST) performed at 73 ± 2.0 °C/15 s on the physicochemical parameters, bioactive compounds, and antioxidant activity of the treated pulp during the refrigeration storage (4 °C) of nance pulp. The material processed by LTLT presented the lowest decrement of ascorbic acid, phenolic compounds, and antioxidant activity (DPPH). Rates of losses of ascorbic acid, phenolic compounds, and antioxidant capacity (DPPH and ABTS) were described by a first order kinetics. The rate constants obtained were higher for HTST pulp, except for the antioxidant capacity determined by ABTS which was slightly higher for LTLT pulp. The t1/2 values were, consequently, larger for LTLT pulp indicating a longer time for deceasing the concentration of the bioactive and the antioxidant capacity. Five main phenolic compounds were identified by HPLC: gallic, trans-ferulic and caffeic acids, rutin, and quercetin and the observed increment of the intensity of quercetin peak for LTLT treated pulp could be due to the breakage of rutin. Both pasteurization methods reduced microbial loads to recommended standards and LTLT reduced it more pronouncedly. LTLT pasteurization could be recommended the best alternative for the pasteurization of this pulp.

Effects of thermal treatments on durum wheat pasta flavour during production process: A modelling approach to provide added-value to pasta dried at low temperatures

Pasta is a key element of the Mediterranean Diet and it has been declared by Unesco intangible cultural heritage of humanity. Despite seems a simple food, only made of semolina and water, pasta is produced following a multi-step process that strongly affect the final product. Drying stage is the one that has the greater influence on its organoleptic/nutritional characteristics. This study aimed to analyse the flavour of pasta to test whether the different drying treatments (High Temperature-Short time or Low Temperature-Long time) have a direct impact on its composition and consequently whether they could influence the end-product quality. The headspace solid-phase microextraction was optimized using an experimental design and 52 samples were analysed by HS-SPME/GC-MS and classified by PLS-DA. The resulting classification model (validated by repeated double cross-validation and permutation tests) allowed correctly predicting more than 80% of samples, confirming that drying may have a significant impact on pasta flavour.

Bile Salt-Stimulated Lipase Activity in Donor Breast Milk Influenced by Pasteurization Techniques.

Breast milk contains bile salt-stimulated lipase (BSSL), which significantly increases the fat digestion capacity of newborns who have limited pancreatic lipase secretion in the first few months after birth. Problematically, Holder pasteurization used in non-profit milk banks to ensure the microbiological safety of donor milk for infants, particularly preterm infants (<37 weeks gestation age), destroys milk BSSL, thus limiting infant fat absorption capacity. Alternative strategies are needed to ensure the safety of donor milk while preserving BSSL activity. Three alternative pasteurization techniques—high-pressure processing (HPP, 550 MPa, 5 min), gamma cell irradiation (IR, 2.5 Mrads) and UV-C (254 nm, 0–33,000 J/L)—were compared with Holder pasteurization (low-temperature long-time, LTLT, 62.5°C, 30 min) for retention of BSSL activity in donor breast milk. As the time required for donor milk pasteurization by UV-C in published methods was not clear, donor breast milk was spiked with seven common bacterial strains and treated by UV-C for variable time periods and the minimum UV-C dosage required to achieve a 5-log10 reduction of CFU/mL was determined. Eight thousand two hundred fifty J/L of UV-C exposure was sufficient to achieve 5-log10 reduction of each of bacterial targets, including Bacillus and Paenibacillus spores. The retention of BSSL activity was highest after HPP (retaining 62% of the untreated milk BSSL activity), followed by UV-C (16,500 J/L), IR and LTLT (35, 29, and 0.3% retention, respectively). HPP was an effective alternative to pasteurize milk with improved retention of BSSL activity compared to Holder pasteurization. Future work should investigate the effect of alternative pasteurization techniques on the entire array of bioactive components in donor breast milk and how these changes affect preterm infant health outcomes. Implementation of HPP technique at milk banks could improve donor milk-fed infant fat absorption and growth.

Comparative study on the microstructure and functional properties of casein in goat milk processed by different methods

SummaryThis work compared the thermal stability, microstructure and functional properties of casein (CN) in goat milk processed by different methods, including homogenisation, low‐temperature long‐time (LTLT), high‐temperature short‐time (HTST), ultrapasteurisation (UP) and ultrahigh temperature (UHT) treatment. The greatest development of CN‐whey protein complexes was observed in LTLT goat milk and the least in HTST goat milk. The CN micelles in LTLT, UP and UHT milk were more obviously changed than the CN micelles in HTST milk, and the random coil content increased significantly after the homogenisation, UP and UHT treatments. The homogenisation had a significant effect on the functional properties of CN. In addition, the most obvious changes in the properties of CN were observed in LTLT and UHT goat milk. The results suggested that homogenisation, pasteurisation and UHT can cause effective changes in the functional properties of CN in goat milk that facilitate its application in the milk industry.

Exploring optimal strategies for aquatic macrophyte pre-treatment: Sustainable feedstock for biohydrogen production

Aquatic macrophytes; Water hyacinth (Eichhornia crassipes) and Azolla, biomass have certain advantages over terrestrial plant biomass to use as non-edible feed for 2nd generation bioenergy production. This is mainly due to the lower lignin content and higher productivity of aquatic macrophytes. These macrophytes do not require arable land. Present study explored on development of factorial approach based optimal pretreatment process for mild acid hydrolysis of Eichhornia crassipes and Azolla microphylla biomass for conversion to fermentable sugars. The simpler structure of aquatic plants translates to higher sugar recovery using milder pretreatment conditions compared to terrestrial plants. H2SO4 & HCl used in mild concentrations for acid hydrolysis experiments. Approximately, 20% of the dry biomass was recovered as fermentable sugar (mainly xylose) upon treatment with dilute sulphuric acid (0.5–1.5% v/v) or hydrochloric acid (2–4% v/v) at 100–120 °C for 30–60 min. Within this range of parameters, sugar yield followed a simple additive model, implying that a decrease in sugar yield is due to reduction of one parameter. This provides a choice between high temperature short time (HTST) and low temperature long time (LTLT) treatments. HTST requires sophisticated pressure vessels and correspondingly higher capital investment for the advantage of a higher throughput. LTLT treatments can be performed in cost economy manner using relatively simple equipment. For economic, environmental and technical reasons, acid addition should be kept to a minimum, which is possible by a choice of higher temperature and longer treatment time. Such pretreatment may be employed as the first step of a two-step pretreatment process prior to enzymatic saccharification of cellulosic fraction. The acid pre-treated hydrolysate of water hyacinth and Azolla microphylla explored for hydrogen production through dark fermentation process through employment of C5 & C6 sugar utilizing microbe Enterobacter cloacae DT-1 strain.

Flavor Characteristics of Low Temperature Long Time (LTLT) and Ultra High Temperature (UHT) Milk

Flavor Characteristics of Low Temperature Long Time (LTLT) and Ultra High Temperature (UHT) Milk

Pasteurization of passion fruit Passiflora setacea pulp to optimize bioactive compounds retention

Passiflora setacea is a wild species of passion fruit with interesting functional properties. Fruit seasonality demands conservation methods to enable its consumption throughout the year. We evaluated High Temperature Short Time (HTST) and Low Temperature Long Time (LTLT) binomials on physical, chemical, antioxidant and sensory characteristics of Passiflora setacea pulps. In natura (IN) and pasteurized pulps were analysed for DPPH, FRAP, ORAC, total phenolic content (TPC), vitamin C, bioactive amines, flavonoids, color, remaining enzymatic activity (REA), microbiological analyzes, sensory evaluation and physical stability. All binomials reached microbiological standards. Binomials 82 °C/20 s and 82 °C/40 s were selected for providing higher total antioxidant activity (TAA), TPC and lower REA. The highest levels of antioxidant activity, flavonoids, vitamin C were kept by 82 °C/20 s, without difference from IN pulp. LTLT binomial showed higher retention of bioactive amines, but also higher REA. Sensory acceptance was not affected by the binomials but pasteurized-cooked flavor was more checked for 82 °C 40 s than IN pulp.

The effect of low-temperature long-time (LTLT) cooking on survival of potentially pathogenic Clostridium perfringens in beef

Low-temperature long-time (LTLT) cooking may lead to risk of potential survival of pathogenic bacteria such as Clostridium perfringens in cooked meat. In this study, the effect of LTLT cooking on C. perfringens was investigated at temperatures commonly used by caterers. Brain heart infusion broth (BHIB) and meat cubes in pouches (vacuumed or non-vacuumed) were inoculated with C. perfringens (NCTC 8238) and heated at temperatures of 48 °C, 53 °C, 55 °C, 60 °C and 70 °C. The viability of C. perfringens in BHIB and meat was monitored using plate counting and the D-value of each thermal treatment was determined. The recovery of C. perfringens after thermal treatment was assessed using optical density measurements. Flow cytometry analysis was used to assess the physiological status (death/injury) of C. perfringens cells in BHIB. The results showed that the required log reduction (6-log) of C. perfringens can be achieved at 55 °C but not at 48 °C or 53 °C. The D-values at all temperatures were higher in meat compared to BHIB while the D-value at 55 °C was higher in non-vacuum compared to vacuum sealed meat. C. perfringens cells were able to recover and grow to pathogenic levels when thermal treatment was unable to achieve the required 6-log reduction. In BHIB, percentage of dead cells increased gradually at 48 °C, 53 °C and 55 °C while an immediate increase (>95%) was observed at 60 °C and 70 °C. These results are important to food safety authorities allowing to set the time-temperature combinations to be used in LTLT cooking to obtain safe meat.

Efektivitas Suhu dan Lama Pasteurisasi Pada Mutu Pasta Bawang merah (Alllium Cepa Var. Aggregatum) Kemasan Standing Pouch

Shallotpaste is an alternative product which can be applied as a spice, one of which is onionpaste. This study aims to determine the temperature and duration of shallot pastepasteurization before being processed into onion paste in standing pouch package.Randomized block design (RBD) 2x3 used as design experiments with pasteurizationtemperature treatment as a T factor, consisting of 2 levels, namely low-temperature longtime (LTLT), called T1, that is red onion paste heated at 65oC for 30 minutes, and high-temperature short time (HTST), called T2, that is red onion paste heated at 75oC for 15 seconds. While the S factor is the storage time consists of 5 levels, namely 4, 8 and 12 days.Storage is carried out at room temperature (27.5oC) with 3 replications. The quality observed was physical appearance, reinforced by the test parameters used including TPCand total acid. The results showed that there were changes in color and aroma that occurredafter 12 days storage into brownish yellow due to enzymatic performance. 60oC pasteurization temperature in 30 minutes is recommended for processing onion paste seenfrom the TPC value below the maximum threshold of SNI with a maximum mean value of9.103 CFU /g.

Effects of low temperature-long time treatments on physicochemical and sensory properties of &lt;i&gt;sous-vide&lt;/i&gt; cooked apples

Effects of low temperature-long time treatments on physicochemical and sensory properties of &lt;i&gt;sous-vide&lt;/i&gt; cooked apples

Interventions of two-stage thermal sous-vide cooking on the toughness of beef semitendinosus

This paper describes the influence of different factors on toughness of beef semitendinosus (ST) by means of low temperature-long time cooking with single-stage (60 °C, 65 °C, 70 °C, and 75 °C for 6 h and 12 h) and two-stage sous-vide procedure (45 + 60 °C, 45 + 65 °C, 45 + 70 °C, and 45 + 75 °C; 49 + 60 °C, 49 + 65 °C, 49 + 70 °C, and 49 + 75 °C for 3 h at the first temperature, and either 3 or 9 h at the second temperature). Reduced toughness of ST beef steak muscle could be attained in 6 h at 60 °C and 45 + 60 °C were due from the minimum shrinkage of sarcomere as well as lower perimysial thickness, cooking loss, and elastic modulus. Collagen solubility showed a positive correlation to the toughness values. The relationship between proteolytic activity and shear force can be seen after 12 h of cooking duration. For the other quality attributes, two stepped cooking temperature-time combination seems to be more effective in preserving the redness values and water content than a single-stage sous-vide method.