The use of spectroscopic techniques and chemometric methods in milk technology

Upotreba i primjena spektroskopskih tehnika u prehrambenoj industriji sve više raste, a odgovori koje daju olakšavaju rješavanje problema u proizvodnji i distribuciji hrane. Primjena spektroskopskih tehnika u mljekarstvu omogućava brzu i jeftinu kvalitativnu i kvantitativnu analizu, ali ima i važnu ulogu u opisivanju strukture i teksture mliječnih proizvoda. Kvalitativna i kvantitativna analiza pojedinih sastojaka u složenim sustavima može biti problematična zbog preklapanja spektralnih odgovora, a kao idealan put za rješenje tog problema je kemometrija, disciplina koja koristi matematičke i statističke metode kako bi oblikovala ili odabrala optimalan mjeriteljski postupak ili eksperiment i omogućila dobivanje, maksimalnog broja informacija analizom dobivenih podataka. Najčešća primjena kemometrije je u analizi skupa podataka i prepoznavanju matematičkih modela. Spektroskopske tehnike u kombinaciji s kemometrijskim metodama omogućavaju praćenje procesa i upravljanje kontrolom kvalitete.The use of spectroscopic techniques is on the rise in food industry, and the answers they provide facilitate problem solving in food production and distribution. The application of spectroscopic techniques in dairy technology allows quick and cheap qualitative and quantitative analyses, and is essential in describing the structure and texture properties of dairy products. The qualitative and quantitative analyses of individual components in composite systems may be problematic due to overlaps in spectral responses. An ideal tool to solve this problem is chemometry, a discipline using mathematical and statistical methods to design or choose an optimum measuring procedure or experiment, and to facilitate obtaining the maximum number of information by analysing the data provided. Chemometry is most frequently used in the analysis of data groups and recognition of mathematic models. Spectroscopic techniques combined with chemometric methods make a valuable tool for process monitoring and quality control management

Karakterizacija i primjena autohtonih starter-kultura u proizvodnji svježeg sira

The use of commercial starter cultures in fresh cheese production from pasteurized milk results in the loss of typical characteristics of artisan fresh cheese due to the replacement of complex native microbiota with a defined starter culture. Hence, the aim of this research is to isolate and characterize dominant lactic acid bacteria (LAB) in artisan fresh cheese and to evaluate their capacity as autochthonous starter cultures for fresh cheese production. Fifteen most prevalent Gram-positive, catalase-negative and asporogenous bacterial strains were selected for a more detailed characterization. Eleven lactic acid bacterial strains were determined to be homofermentative cocci and four heterofermentative lactobacilli. Further phenotypic and genotypic analyses revealed that those were two different LAB strains with high acidifying and proteolytic activity, identified as Lactobacillus fermentum A8 and Enterococcus faecium A7. These two autochthonous strains, alone or in combination with commercial starter, were used to produce different types of fresh cheese, which were evaluated by a panel. Conventional culturing, isolation, identification and PCR-denaturing gradient gel electrophoresis (PCR-DGGE) procedures, applied to the total fresh cheese DNA extracts, were employed to define and monitor the viability of the introduced LAB strains and their effect on the final product characteristics. Production of fresh cheese using a combination of commercial starter culture and selected autochthonous strains resulted in improved sensorial properties, which were more similar to the ones of spontaneously fermented fresh cheese than to those of cheese produced with only starter culture or selected strains. After 10 days of storage, that cheese retained the best sensorial properties in comparison with all other types of cheese. The presence of inoculated autochthonous and starter cultures and their identification was demonstrated by DGGE analysis. The obtained results indicate that autochthonous strains have a strong potential to enrich the flavour of industrially produced fresh type cheese under controlled conditions.Primjenom komercijalnih starter-kultura u proizvodnji svježeg sira iz pasteriziranog mlijeka gube se specifična svojstva tradicionalno proizvedenog svježeg sira zbog zamjene prirodno prisutne kompleksne mikrobiote definiranim komercijalnim starter-kulturama. Stoga je svrha ovih istraživanja bila izolirati i okarakterizirati bakterije mliječne kiseline (BMK) koje prevladavaju u tradicionalnom svježem siru i ustanoviti mogućnost njihove primjene kao autohtonih starter-kultura za proizvodnju svježeg sira. Za detaljniju je karakterizaciju odabrano petnaest Gram-pozitivnih, katalaza-negativnih i nesporogenih bakterijskih sojeva koji su prevladavali u autohtonoj mikrobnoj populaciji izoliranoj iz svježeg sira. Jedanaest ih je okarakterizirano kao homofermentativni koki, a četiri kao heterofermentativni laktobacili. Na temelju fenotipske i genotipske analize ustanovljeno je da se radi o dva različita soja BMK koji brzo zakiseljavaju hranjivi medij i imaju proteolitičku aktivnost, a identificirani su kao Lactobacillus fermentum A8 i Enterococcus faecium A7. Ta su dva autohtona soja BMK, sama ili u kombinaciji s komercijalnom starter-kulturom, upotrijebljena za proizvodnju različitih uzoraka svježih sireva. Radi praćenja aktivnosti dodanih BMK i njihova utjecaja na svojstva konačnog proizvoda, provedene su kemijske i senzorske analize te konvencionalni uzgoj, izolacija i identifikacija bakterijskih sojeva iz uzoraka svježih sireva. Primjenom autohtonih sojeva u kombinaciji s komercijalnom starter-kulturom poboljšana su senzorska svojstva proizvedenih svježih sireva u usporedbi s onima u koje je dodana ili samo komercijalna starter-kultura ili samo autohtona kultura. Isti su sirevi zadržali najbolja senzorska svojstva i nakon deset dana čuvanja. PCR elektroforezom u denaturirajućem gradijentu (PCR-DGGE) ekstrahirane ukupne DNA iz svježeg sira potvrđena je prisutnost i provedena identifikacija inokulirane autohtone i starter-kulture. Prema dobivenim rezultatima može se zaključiti da odabrani autohtoni sojevi BMK mogu poboljšati aromu svježih sireva koji se industrijski proizvode u kontroliranim uvjetima

Karakterizacija i primjena autohtonih starter-kultura u proizvodnji svježeg sira

The use of commercial starter cultures in fresh cheese production from pasteurized milk results in the loss of typical characteristics of artisan fresh cheese due to the replacement of complex native microbiota with a defined starter culture. Hence, the aim of this research is to isolate and characterize dominant lactic acid bacteria (LAB) in artisan fresh cheese and to evaluate their capacity as autochthonous starter cultures for fresh cheese production. Fifteen most prevalent Gram-positive, catalase-negative and asporogenous bacterial strains were selected for a more detailed characterization. Eleven lactic acid bacterial strains were determined to be homofermentative cocci and four heterofermentative lactobacilli. Further phenotypic and genotypic analyses revealed that those were two different LAB strains with high acidifying and proteolytic activity, identified as Lactobacillus fermentum A8 and Enterococcus faecium A7. These two autochthonous strains, alone or in combination with commercial starter, were used to produce different types of fresh cheese, which were evaluated by a panel. Conventional culturing, isolation, identification and PCR-denaturing gradient gel electrophoresis (PCR-DGGE) procedures, applied to the total fresh cheese DNA extracts, were employed to define and monitor the viability of the introduced LAB strains and their effect on the final product characteristics. Production of fresh cheese using a combination of commercial starter culture and selected autochthonous strains resulted in improved sensorial properties, which were more similar to the ones of spontaneously fermented fresh cheese than to those of cheese produced with only starter culture or selected strains. After 10 days of storage, that cheese retained the best sensorial properties in comparison with all other types of cheese. The presence of inoculated autochthonous and starter cultures and their identification was demonstrated by DGGE analysis. The obtained results indicate that autochthonous strains have a strong potential to enrich the flavour of industrially produced fresh type cheese under controlled conditions.Primjenom komercijalnih starter-kultura u proizvodnji svježeg sira iz pasteriziranog mlijeka gube se specifična svojstva tradicionalno proizvedenog svježeg sira zbog zamjene prirodno prisutne kompleksne mikrobiote definiranim komercijalnim starter-kulturama. Stoga je svrha ovih istraživanja bila izolirati i okarakterizirati bakterije mliječne kiseline (BMK) koje prevladavaju u tradicionalnom svježem siru i ustanoviti mogućnost njihove primjene kao autohtonih starter-kultura za proizvodnju svježeg sira. Za detaljniju je karakterizaciju odabrano petnaest Gram-pozitivnih, katalaza-negativnih i nesporogenih bakterijskih sojeva koji su prevladavali u autohtonoj mikrobnoj populaciji izoliranoj iz svježeg sira. Jedanaest ih je okarakterizirano kao homofermentativni koki, a četiri kao heterofermentativni laktobacili. Na temelju fenotipske i genotipske analize ustanovljeno je da se radi o dva različita soja BMK koji brzo zakiseljavaju hranjivi medij i imaju proteolitičku aktivnost, a identificirani su kao Lactobacillus fermentum A8 i Enterococcus faecium A7. Ta su dva autohtona soja BMK, sama ili u kombinaciji s komercijalnom starter-kulturom, upotrijebljena za proizvodnju različitih uzoraka svježih sireva. Radi praćenja aktivnosti dodanih BMK i njihova utjecaja na svojstva konačnog proizvoda, provedene su kemijske i senzorske analize te konvencionalni uzgoj, izolacija i identifikacija bakterijskih sojeva iz uzoraka svježih sireva. Primjenom autohtonih sojeva u kombinaciji s komercijalnom starter-kulturom poboljšana su senzorska svojstva proizvedenih svježih sireva u usporedbi s onima u koje je dodana ili samo komercijalna starter-kultura ili samo autohtona kultura. Isti su sirevi zadržali najbolja senzorska svojstva i nakon deset dana čuvanja. PCR elektroforezom u denaturirajućem gradijentu (PCR-DGGE) ekstrahirane ukupne DNA iz svježeg sira potvrđena je prisutnost i provedena identifikacija inokulirane autohtone i starter-kulture. Prema dobivenim rezultatima može se zaključiti da odabrani autohtoni sojevi BMK mogu poboljšati aromu svježih sireva koji se industrijski proizvode u kontroliranim uvjetima

Influence of refrigeration and ageing time on textural characteristics of fresh meat

Research of the textural characteristics of pork, beef and baby beef meat samples was conducted. Hardness and adhesivity of the meat was measured immediately after slaughtering, then after 24, 48 and 72 hours. Half of the samples were kept at room temperature, while the other half were refrigerated at 4 C. The results showed that the hardness and adhesivity suddenly dropped during the first 24 hours (up to 345 N, or 41.7 %). After next 48 hours of storage, the values of measured textural properties showed a slight decrease (only additional 15.6 %). The refrigerated samples retained their textural properties a lot better (31 % decrease in hardness during first 24 h, additional 7.4 % in the next 48 hours) than the non-refrigerated ones. In correlation with consumer and industry experience with the texture of cooked or fried meat, refrigeration is a better choice after 48 hours, while after that period, meat at room temperature, is too soft for further processing

Determination of Textural Properties of Gouda Cheese

Tekstura kao manifestacija nekih reoloških svojstava namirnice jedna je od osnovnih organoleptičkih svojstava, te ima vrlo važnu ulogu pri rukovanju, obradi i ponašanju namirnica. Potrošačima je također tekstura jedan od važnijih parametara kojim se rukovode prilikom odabira proizvoda. Na analizatoru teksture TA.HDPlus izvršena je instrumentalna analiza pet sireva Gouda različitih proizvođača koji su prisutni na hrvatskom tržištu. Od teksturalnih parametara ispitivane su tvrdoća, rad potreban za žvakanje, elastičnost i adhezivnost te njihova ovisnost o udjelu suhe tvari.Najtvrđim (11,88 N ± 1,79) su se pokazali uzorci s najvećim udjelom suhe tvari (55 %). Padom udjela suhe tvari smanjuju se vrijednosti tvrdoće, adhezivnosti i rada potrebnog za prvi zagriz. Elastičnost raste s porastom udjela vode te je najveća elastičnost bila 14,02 mm, uz 50 % udjela vode. Rad potreban za prvi zagriz linearno ovisi o sva tri teksturna parametra gdje je 138,24 mJ najveća dobivena vrijednost pri 55 % suhe tvari.Texture as a manifestation of some rheological properties of foodstuffs is one of the primary organoleptic properties. It has important role in handling, processing and behaviour of the foodstuffs. From consumer aspect, texture is also one of the more important parameters which they use for their buying decisions. Instrumental analysis on TA.HDPlus texture analyzer of five Gouda cheeses from various Croatian producers was conducted. From wide range of textural properties, hardness, work for mastication, elasticity and adhesivity were chosen for testing, as well as for comparing with dry matter content. Hardest (11,88 N ± 1,79) samples have largest share of dry matter (55 %). With decrease of dry matter content, values for hardness, adhesivity and work dropped. Elasticity rise with increase of water content, i.e. largest elasticity was 14,02 mm, with 50 % water content. Work linearly depends on all three measured textural properties. 138,24 mJ was largest measured value for sample, which contain 55 % of dry matter

Impact of pumpkin seed oil and coffee treatment on the characteristics of semi-hard cheese

Semi-hard cheese was made from fresh domestic cow milk and treated with pumpkin seed oil and coffee during its ageing. The energy value and composition of the cheese were examined by determining the content of dry matter, minerals, proteins, fat, caffeine and fatty acids. During the ageing period, the cheese was dipped into a sweet, freshly-prepared, high-quality coffee drink and coated with a mixture of milled coffee grains and cold pressed pumpkin seed oil to improve the sensory properties of the cheese, but also to improve its nutritional value. It is considered that treated cheese could have greater nutritional and pro-health properties then untreated cheese, due to nutritional and healing properties of pumpkin seed oil and coffee used during the maturation period. Pumpkin seed oil contains carbohydrates, minerals, proteins, and important unsaturated fatty acids, while coffee is rich in antioxidants and helps in the prevention of type 2 diabetes, Parkinson\u27s and Alzheimer\u27s disease, and high cholesterol. To determine the impact of the treatment, the fatty acid and caffeine contents were determined by the GC-FID and the UPLC-DAD method. The cheese treated with pumpkin seed oil and coffee had a higher amount of unsaturated fatty acids (UFA) and a lower amount of saturated fatty acids (SFA) than the untreated cheese. The proportions of long-chain UFA, such as the C18:2n6c (Omega 6) and the C18:3n3 (Omega 3), were higher in the treated cheese than those in the untreated cheese, as well as the C20:1, the C22:2 and the C24:1, which were not detected in the untreated cheese. Caffeine concentration in the treated cheese was 33.08 mg/L

Protection of organic cereals from insect and rodent pests in a warehouse by combined use of traps and sticky tapes

Several options of protection of organic cereals (winter and spring wheat, rye and maize) from insect and rodent pests, using a combination of traps (with or without pheromone/ attractant) and sticky tapes and no chemicals, were tested in a warehouse over the summerspring season of 2019/2020. Temperature in the warehouse was 14-29°C and humidity around 50%. The average grain moisture of winter and spring wheat and rye was 10-11%, while it was 12-14% in maize grain, and the average grain temperature of all cereals was 13-27°C. Regarding stored-product insect pests, five coleopteran, two moth and one Psocoptera species were detected, and the coleopterans predominated (98.5%) along with secondary pest insects (94.0%). Regarding rodents, only specimens of Mus musculus were found throughout the test period, their maximum monthly frequency being 72 (in January 2020). A combination of traps (with or without pheromones) and sticky tape barriers was found to provide an effective tool for trapping insects. Also, snap traps and trapping boxes for killing rodents, when used simultaneously with sticky tape barriers, were found to provide good protection of cereals from house mice. The pest control effect was also confirmed by collecting samples of organic cereal grain, which showed no significant presence of stored-product insects or grain damage (0.94% and 0.96% in spring wheat and rye, respectively) at the end of the test period. The results showed a great potential of combined application of traps and sticky tapes for protecting organic cereals in horizontal bulk storages, but the use of chemicals approved for organic food production would be required under extended storage periods

Influence of probiotic cultures addition on the properties of semi-hard ewe’s cheese

Dodatak probiotičkih bakterija u fermentirane mliječne napitke bio je predmet mnogih istraživanja, međutim dodatak tih bakterija u sireve, posebno one proizvedene od ovčjeg mlijeka, nije do sada detaljno istražen. Stoga su u ovom radu proizvedeni probiotički polutvrdi ovčji sirevi s dodatkom probiotika Bifidobacterium animalis subsp. lactis BB-12 i Lactobacillus acidophilus LA-5. Zrenje sireva se odvijalo 45 dana pri 13 °C i 85 % relativne vlažnosti. Tijekom tog razdoblja određivani su kemijski parametri i provedene su mikrobiološke analize proizvedenih probiotičkih sireva. Dodatak probiotičkih kultura nije značajno utjecao na kemijska i mikrobiološka svojstva proizvedenih sireva u usporedbi s kontrolnim sirevima bez dodatka probiotičkih kultura. Broj živih probiotičkih bakterija održao se na ca 106-107 CFU/g probiotičkih sireva tijekom 45 dana zrenja, što je potvrđeno RAPD metodom. Probiotički polutvrdi ovčji sirevi s bakterijom Bifidobacterium animalis subsp. lactis BB-12 su imali slična senzorska svojstva sirevima proizvedenim bez dodatka probiotika, dok je dodatak bakterije Lactobacillus acidophilus LA-5 doveo do poboljšanja okusa polutvrdog ovčjeg sira. Dobiveni rezultati pokazuju da je polutvrdi ovčji sir pogodan matriks za primjenu probiotičkih kultura Bifidobacterium animalis subsp. lactis BB-12 i Lactobacillus acidophilus LA-5.Addition of probiotic bacteria into fermented milk beverages has been the subject of many studies, however, addition of these bacteria into cheeses, especially the ones made from ewe’s milk, has not been thoroughly investigated. Therefore, the aim of this study was to produce probiotic semi-hard ewe’s cheese with addition of probiotic strain Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus acidophilus LA-5. Cheese ripening occurred during 45 days at 13 °C and 85 % of relative humidity. During that period, chemical parameters were determined and microbiological analysis of manufactured probiotic cheeses was performed. Addition of probiotic cultures did not significantly influence the chemical properties and microbiological quality of produced cheeses in comparison with the control cheeses without addition of probiotic cultures. Number of live probiotic bacteria remained at about 106-107 CFU/g of probiotic cheeses during 45 days of ripening, which was confirmed by RAPD method. Sensory properties of probiotic semi-hard ewe’s cheese with Bifidobacterium animalis subsp. lactis BB-12 were similar to those obtained for cheeses without addition of probiotic, while addition of Lactobacillus acidophilus LA-5 improved the taste of cheeses. Obtained results demonstrated that semi-hard ewe’s cheese can be an effective matrix for addition of probiotic cultures Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus acidophilus LA-5

Effect of screw configuration, moisture content and particle size of corn grits on properties of extrudates

Extrusion is a modern procedure for processing different types of raw materials and production of wide range of food products, where the corn grits are often used as main raw materials. Therefore the aim of this study was to determine the effect of screw configuration (4:1 and 1:1), moisture content (15% and 20%) and particle size of corn grits (>500 µm and <500 µm) on properties of extrudates. Samples were extruded in the laboratory single screw extruder Brabender 19/20 DN, at temperature profile 135/170/170 °C, using die with 4 mm diameter. Physical and rheological properties, digestibility and starch damage of the obtained extrudates were determined, and results were compared with control samples of non-extruded corn grits. Lower moisture content and usage of screw with compression ratio 4:1 increased expansion ratio and fracturability, but decreased bulk density and hardness of extrudates, regardless of granularity. After extrusion process water absorption index increased, but peak, hot and cold viscosity of all samples decreased, with more pronounced effect in grits extruded with lower moisture content and with screw 4:1. Extrusion caused a reduction of the resistant starch content and increase starch damage of all samples

High Heat Treatment of Goat Cheese Milk. The Effect on Sensory Profile, Consumer Acceptance and Microstructure of Cheese

Goat cheeses from high heat treated milk (HHTM: 80◦C/5 min (E1) and 90◦C/5 min (E2)), could be regarded as new products, compared to their analogues made from commonly pasteurized milk (65◦C/30 min (C)). Descriptive analysis and consumer tests with a hedonic scale and JAR scale were part of the product development process. The use of scanning electron microscopy enabled deeper insight into the flavor and texture of the cheeses. In all cheese variants, goaty flavor was mildly pronounced. Young HHTM cheeses also had a pronounced whey and cooked/milky flavor. Consumers found such flavor ‘too intensive’. Unlike the control variant, HHTM cheeses were not described as ‘too hard’. Such improvement in texture was found to be a result of fine, highly branched microstructure, sustained over the course of ripening time and highly incorporated milk fat globules inside the cheese mass. Cluster analysis showed that the largest group of consumers (47.5%) preferred E2 cheese. Although consumers found that most of the cheeses were ‘too salty’, this excess did not decrease their overall acceptance. Neither microstructure analysis nor descriptive sensory analysis of goat white brined cheeses produced from high heat treated milk has been done before