Detailed mineral profile of milk, whey, and cheese from cows, buffaloes, goats, ewes and dromedary camels, and efficiency of recovery of minerals in their cheese.

Milk and dairy products are important in the human diet not only for the macro nutrients, such as proteins and fats, that they provide, but also for the supply of essential micronutrients, such as minerals. Minerals are present in milk in soluble form in the aqueous phase and in colloidal form associated with the macronutrients of the milk. These 2 forms affect the nutritional functions of the minerals and their contribution to the technological properties of milk during cheese-making. The aim of the present work was to study and compare the detailed mineral profiles of dairy foods (milk, whey, and cheese) obtained from cows, buffaloes, goats, ewes and dromedary camels, and to analyze the recovery in the curd of the individual minerals according to a model cheese-making procedure applied to the milk of these 5 dairy species. The detailed mineral profile of the milk samples was obtained by inductively coupled plasma - optical emission spectroscopy (ICP - OES). We divided the 21 minerals identified in the 3 different matrices into essential macro- and micro-minerals, and environmental micro-minerals, and calculated the recovery of the individual minerals in the cheeses. The complete mineral profiles and the recoveries in the cheeses were then analyzed using a linear mixed model with Species and Food, and their interaction included as fixed effects, and Sample within Species as a random effect. The mineral profiles of each food matrix were then analyzed separately with a general linear model in which only the fixed effect of Species was included. The results showed that the species could be divided into 2 groups: those producing a more diluted milk characterized by a higher content of soluble minerals (in particular K), and those with a more concentrated milk with a higher colloidal mineral content in the skim of the milk (such as Ca and P). The recoveries of the minerals in the curd were in line with the initial content in the milk, and also highlighted the fact that the influence of the brine was not limited to the Na content but to its whole mineral makeup. These results provide valuable information for the evaluation of the nutritional and technological properties of milk, and for the uses made of the byproducts of cheese making from the milk of different species.

Two-stage preparation of highly mesoporous carbon for super-adsorption of paracetamol and tetracycline in water: Important contribution of pore filling and π-π interaction.

This study aimed to develop an extremely highly porous activated carbon derived from soybean curd residues (SCB-AC) through two-step pyrolyzing coupled with KOH activating process and then apply it for removing paracetamol (PRC) and tetracycline (TCH) from water. The optimal conditions for chemical activation were 800 °C and the ratio of KOH to material (4/1; wt./wt.). SCB-AC adsorbents (before and after adsorption) were characterized by Brunauer-Emmet-Teller (BET) analyser, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy, and Raman spectroscopy. Adsorption kinetics, isotherm, and thermodynamics were concluded under batch experiments. The effects of pH (2-10) and NaCl (0-1 M) on adsorption processes were investigated. Reusable properties of laden SCB-AC were evaluated by studying desorption and cycles of adsorption/desorption. Results indicated that SCB-AC exhibited a large specific surface area (3306 m2/g) and high total pore volume (2.307 cm3/g), with mesoporous volume accounting for 86.9%. Its porosity characteristics (average pore width: 2.725 nm) are very appropriate for adsorbing two pharmaceuticals through pore-filling mechanism. Adsorption processes were less affected by the parameters: pH, NaCl, and water matrixes. The kinetics for adsorbing PRC reached a faster equilibrium than that for TCH. The Langmuir maximum adsorption capacity of SCB-AC (pHeq 7.0 and 25 °C) was 1235 mg/g (for adsorbing TCH) and 646 mg/g (PRC). Pore filling (confirmed by BET analyser) and π-π interaction (confirmed by FTIR and Raman spectroscopy) were dominant adsorption mechanisms. Those mechanisms were physisorption (ΔH° = 13.71 and -21.04 kJ/mol for adsorbing TCH and PRC, respectively). SCB-AC can serve as an outstanding material for removing pharmaceuticals from water.

ß-Casein A1 and A2: Effects of polymorphism on the cheese-making process.

Of late, "A2 milk" has gained prominence in the dairy sector due to its potential implications in human health. Consequently, the frequency of A2 homozygous animals has considerably increased in many countries. To elucidate the potential implications that beta casein (ß-CN) A1 and A2 may have on cheese-making traits, it is fundamental to investigate the relationships between the genetic polymorphisms and cheese-making traits at the dairy plant level. Thus, the aim of the present study was to evaluate the relevance of the ß-CN A1/A2 polymorphism on detailed protein profile and cheese-making process in bulk milk. Based on the ß-CN genotype of individual cows, 5 milk pools diverging for presence of the 2 ß-CN variants were obtained: (1) 100% A1; (2) 75% A1 and 25% A2; (3) 50% A1 and 50% A2; (4) 25% A1 and 75% A2; and (5) 100% A2. For each cheese-making day (n = 6), 25 L of milk (divided into 5 pools, 5 L each) were processed, for a total of 30 cheese-making processes. Cheese yield, curd nutrient recovery, whey composition, and cheese composition were assessed. For every cheese-making process, detailed milk protein fractions were determined through reversed-phase HPLC. Data were analyzed by fitting a mixed model, which included the fixed effects of the 5 different pools, the protein and fat content as a covariate, and the random effect of the cheese-making sessions. Results showed that the percentage of κ-CN significantly decreased up to 2% when the proportion of ß-CN A2 in the pool was ≥25%. An increase in the relative content of ß-CN A2 (≥50% of total milk processed) was also associated with a significantly lower cheese yield both 1 and 48 h after cheese production, whereas no effects were observed after 7 d of ripening. Concordantly, recovery of nutrients reflected a more efficient process when the inclusion of ß-CN A2 was ≤75%. Finally, no differences in the final cheese composition obtained by the different ß-CN pools were observed.

Manufacture of process cheese products without emulsifying salts using acid curd and micellar casein concentrate.

Process cheese products (PCP) are dairy foods prepared by blending dairy ingredients (such as natural cheese, protein concentrates, butter, nonfat dry milk, whey powder, and permeate) with nondairy ingredients [such as sodium chloride, water, emulsifying salts (ES), color, and flavors] and then heating the mixture to obtain a homogeneous product with an extended shelf life. The ES, such as sodium citrate and disodium phosphate, are critical for the unique microstructure and functional properties of PCP because they improve the emulsification characteristics of casein by displacing the calcium phosphate complexes that are present in the insoluble calcium-paracaseinate-phosphate network in natural cheese. The objectives of this study were to determine the optimum protein content (3, 6, and 9% protein) in micellar casein concentrate (MCC) to produce acid curd and to manufacture PCP using a combination of acid curd cheese and MCC that would provide the desired improvement in the emulsification capacity of caseins without the use of ES. To produce acid curd, MCC was acidified using lactic acid to get a pH of 4.6. In the experimental formulation, the acid curd was blended with MCC to have a 2:1 ratio of protein from acid curd relative to MCC. The PCP was manufactured by blending all ingredients in a KitchenAid blender (Professional 5 Plus, KitchenAid) to produce a homogeneous paste. A 25-g sample of the paste was cooked in the rapid visco analyzer (RVA) for 3 min at 95°C at 1,000 rpm stirring speed during the first 2 min and 160 rpm for the last min. The cooked PCP was then transferred into molds and refrigerated until further analysis. This trial was repeated 3 times using different batches of acid curd. MCC with 9% protein resulted in acid curd with more adjusted yield. The end apparent viscosity (402.0-483.0 cP), hardness (354.0-384.0 g), melting temperature (48.0-51.0°C), and melting diameter (30.0-31.4 mm) of PCP made from different acid curds were slightly different from the characteristics of typical PCP produced with conventional ingredients and ES (576.6 cP end apparent viscosity, 119.0 g hardness, 59.8°C melting temperature, and 41.2 mm melting diameter) due to the differences in pH of final PCP (5.8 in ES PCP compared with 5.4 in no ES PCP). We concluded that acid curd can be produced from MCC with different protein content. Also, we found that PCP can be made with no ES when the formulation uses a 2:1 ratio of acid curd relative to MCC (on a protein basis).

Manufacture of a novel cultured micellar casein concentrate ingredient for emulsifying salt-free process cheese products applications.

Micellar casein concentrate (MCC) is a high protein ingredient that is typically produced using 3 stages of microfiltration with a 3× concentration factor and diafiltration. Acid curd is an acid protein concentrate, which can be obtained by precipitating the casein at pH 4.6 (isoelectric point) using starter cultures or direct acids without the use of rennet. Process cheese product (PCP) is a dairy food prepared by blending dairy ingredients with nondairy ingredients and then heating the mixture to get a product with an extended shelf-life. Emulsifying salts are critical for the desired functional characteristics of PCP because of their role in calcium sequestration and pH adjustment. The objectives of this study were to develop a process to produce a novel cultured micellar casein concentrate ingredient (cMCC; culture-based acid curd) and to produce PCP without emulsifying salts using different combinations of protein from cMCC and MCC in the formulations (2.0:1.0, 1.9:1.1, and 1.8:1.2). Skim milk was pasteurized at 76°C for 16 s and then microfiltered in 3 microfiltration stages using graded permeability ceramic membranes to produce liquid MCC (11.15% total protein; TPr and 14.06% total solids; TS). Part of the liquid MCC was spray dried to produce MCC powder (75.77% TPr and 97.84% TS). The rest of the MCC was used to produce cMCC (86.9% TPr and 96.4% TS). Three PCP treatments were formulated with different ratios of cMCC:MCC, including 2.0:1.0, 1.9:1.1, and 1.8:1.2 on the protein basis. The composition of PCP was targeted to 19.0% protein, 45.0% moisture, 30.0% fat, and 2.4% salt. This trial was repeated 3 times using different batches of cMCC and MCC powders. All PCP were evaluated for their final functional properties. No significant differences were detected in the composition of PCP made with different ratios of cMCC and MCC except for the pH. The pH was expected to increase slightly with elevating the MCC amount in the PCP formulations. The end apparent viscosity was significantly higher in 2.0:1.0 formulation (4,305 cP) compared with 1.9:1.1 (2,408 cP) and 1.8:1.2 (2,499 cP). The hardness ranged from 407 to 512 g with no significant differences within the formulations. However, the melting temperature showed significant differences with 2.0:1.0 having the highest melting temperature (54.0°C), whereas 1.9:1.1 and 1.8:1.2 showed 43.0 and 42.0°C melting temperature, respectively. The melting diameter (38.8 to 43.9 mm) and melt area (1,183.9 to 1,538.6 mm2) did not show any differences in different PCP formulations. The PCP made with a 2.0:1.0 ratio of protein from cMCC and MCC showed better functional properties compared with other formulations.

Reduction of Beta Cyclodextrin by Curd Washing in Low-Cholesterol Manchego Cheese.

Beta-cyclodextrin (ß-CD) is a cyclic oligosaccharide consisting of seven glucose units. ß-CD is increasingly used in food research to reduce cholesterol due to its affinity for non-polar molecules such as cholesterol and as a natural additive. The purpose of this study was to evaluate the effect of curd washing in ewe's milk cheese on the reduction in cholesterol by ß-CD from pasteurized ewe's milk Manchego cheese and the characteristics of its main components: milk, lipids, and flavor. An approximately 98.45% cholesterol reduction was observed in washed experimental cheeses that were treated by using ß-CD. The remaining residual ß-CD from the effect of curd washing was 0.15% in mature cheese, of the initial 1% ß-CD treatment of the milk. The chemical properties (fat, moisture, and protein) did not change as a result of the curd washing with or without ß-CD. The curd washing with or without ß-CD on the levels of the various lipid fraction (fatty acids, triglycerides, and phospholipids) were comparable in treated and untreated cheeses. The effects of curd washing and the ß-CD treatment did not significantly affect flavor components or short chain free fatty acids. The ß-CD molecules were edible and nontoxic; as a result, they could be used safely in cholesterol removal processing in cheese manufacturing, improving the reduction in residual ß-CD by curd washing by 85%. Therefore, the present study suggests that curd washing combined with ß-CD is an effective process for cholesterol removal in Manchego cheese, preserving its desirable properties.

Use of Dairy Products in people living with diabetes.

Dairy products are a good source of protein, energy and calcium. Unfortunately, because of various misconceptions, they are often avoided by people living with diabetes. This article enumerates the wide variety of dairy products available in the South Asian cuisine, explores their nutritional characteristics, and explains how to consume them in a healthy manner. Furthermore, this manuscript also highlights the utility of dairy products in people living with diabetes and its impact on improving glycemic control.

Time Courses of Gastric Volume and Content after Different Types of Casein Ingestion in Healthy Men: A Randomized Crossover Study.

BACKGROUND: Few studies have evaluated differences in the curd-forming ability of casein on gastric volume and content directly after ingestion in humans. OBJECTIVES: This study evaluated the time course of gastric volume and curd conditions in the stomach after protein ingestion. METHODS: This was an open-labeled, randomized crossover trial. Ten healthy men [age: 33.4 ± 7.3 y; BMI (kg/m2): 21.9 ± 0.9] received 350 g of 3 isonitrogenous and isocaloric protein drinks containing 30 g micellar casein (MCN), sodium caseinate (SCN), or whey protein concentrate (WPC). The gastric antrum cross-sectional area (CSA) and curd in the stomach were measured using ultrasonography within 5 h after ingestion. The differences between test foods were tested using the MIXED model and post hoc tests using Fisher's protected least significant difference. RESULTS: The incremental AUC of the gastric antrum CSA after MCN ingestion was 1.3-fold and 1.5-fold higher than that after the ingestion of SCN and WPC, respectively (both P < 0.05), but not different between SCN and WPC. The number of participants with curds ≥20 mm with a high echogenicity clot observed in the stomach within 5 h after MCN ingestion was significantly greater than that after the ingestion of other proteins (n = 9 for MCN, n = 2 for SCN, and n = 0 for WPC; bothP < 0.01). The regression line slopes on total plasma amino acid concentration and gastric antrum CSA were significantly different between the participants with and without curds. CONCLUSIONS: In contrast to SCN and WPC, MCN ingestion resulted in slow kinetics of gastric antrum CSA. Differences in curd formation of casein in the stomach affect gastric emptying and plasma amino acid absorption kinetics after ingestion in healthy men. This trial was registered at University Hospital Medical Information Network Clinical Trials Registry as UMIN000038388 (https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000043746).

Food waste and soybean curd residue composting by black soldier fly.

This study attempted to manage the food waste and soybean curd residue generated in Taiwan's National Ilan University by black soldier fly-aided co-composting. The food waste and soybean curd residue were co-composted with rice husk as a bulking agent in 4:1 ratio and 0.42 mg BSF/g waste. The higher organic matter degradation of 31.9% was found in Container B (black soldier flies aided food waste and rice husk co-composting) with a rate constant of 0.14 d-1. In Container D (black soldier flies aided soybean curd residue and rice husk co-composting), the organic matter degradation of 29.4% was found with a rate constant of 0.29 d-1. The matured compost of 6.02 kg was obtained from 20 kg of food waste, while 5.83 kg of matured compost was generated from 20 kg of soybean curd residue. The physico-chemical parameters of the final matured compost were in the favorable range of Taiwan's compost standards. The germination index was 188.6% and 194.78% in Containers B and D, respectively. The present study will expand the application of BSF at the institutional level which prove to be a feasible solution for rapid, clean, and efficient composting of post-consumer food wastes.

Chemical interactions among caseins during rennet coagulation of milk.

Rennet milk curds were prepared under 4 different temperature and acidity conditions. The development of different types of inter-protein chemical bonds (disulfide, hydrophobic, electrostatic, hydrogen, and calcium bridges) was monitored for 60 min after curd cutting. Hydrophobic inter-protein interactions originally present in casein micelles in milk were substituted by electrostatic, hydrogen, and calcium bonds throughout the curd curing period. Disulfide bonds were not disturbed by the experimental conditions employed in the study, remaining at a constant level in all studied treatments. Acidification of curds increased the availability of soluble ionic calcium, increasing the relative proportion of calcium bridges at the expense of electrostatic-hydrogen bonds. Although pH defined the nature of the interactions established among proteins in curd, temperature modified the rate at which such bonds were formed.

Composition and aptitude for cheese-making of milk from cows, buffaloes, goats, sheep, dromedary camels, and donkeys.

Bovines produce about 83% of the milk and dairy products consumed by humans worldwide, the rest represented by bubaline, caprine, ovine, camelid, and equine species, which are particularly important in areas of extensive pastoralism. Although milk is increasingly used for cheese production, the cheese-making efficiency of milk from the different species is not well known. This study compares the cheese-making ability of milk sampled from lactating females of the 6 dairy species in terms of milk composition, coagulation properties (using lactodynamography), curd-firming modeling, nutrients recovered in the curd, and cheese yield (through laboratory model-cheese production). Equine (donkey) milk had the lowest fat and protein content and did not coagulate after rennet addition. Buffalo and ewe milk yielded more fresh cheese (25.5 and 22.9%, respectively) than cow, goat, and dromedary milk (15.4, 11.9, and 13.8%, respectively). This was due to the greater fat and protein contents of the former species with respect to the latter, but also to the greater recovery of fat in the curd of bubaline (88.2%) than in the curd of camelid milk (55.0%) and consequent differences in the recoveries of milk total solids and energy in the curd; protein recovery, however, was much more similar across species (from 74.7% in dromedaries to 83.7% in bovine milk). Compared with bovine milk, the milk from the other Artiodactyla species coagulated more rapidly, reached curd firmness more quickly (especially ovine milk), had a more pronounced syneresis (especially caprine milk), had a greater potential asymptotical curd firmness (except dromedary and goat milk), and reached earlier maximum curd firmness (especially caprine and ovine milk). The maximum measured curd firmness was greater for bubaline and ovine milk, intermediate for bovine and caprine milk, and lower for camelid milk. The milk of all ruminant species can be used to make cheese, but, to improve efficiency, cheese-making procedures need to be optimized to take into account the large differences in their coagulation, curd-firming, and syneresis properties.

Genome sequencing sheds light on the contribution of structural variants to Brassica oleracea diversification.

BACKGROUND: Brassica oleracea includes several morphologically diverse, economically important vegetable crops, such as the cauliflower and cabbage. However, genetic variants, especially large structural variants (SVs), that underlie the extreme morphological diversity of B. oleracea remain largely unexplored. RESULTS: Here we present high-quality chromosome-scale genome assemblies for two B. oleracea morphotypes, cauliflower and cabbage. Direct comparison of these two assemblies identifies ~ 120 K high-confidence SVs. Population analysis of 271 B. oleracea accessions using these SVs clearly separates different morphotypes, suggesting the association of SVs with B. oleracea intraspecific divergence. Genes affected by SVs selected between cauliflower and cabbage are enriched with functions related to response to stress and stimulus and meristem and flower development. Furthermore, genes affected by selected SVs and involved in the switch from vegetative to generative growth that defines curd initiation, inflorescence meristem proliferation for curd formation, maintenance and enlargement, are identified, providing insights into the regulatory network of curd development. CONCLUSIONS: This study reveals the important roles of SVs in diversification of different morphotypes of B. oleracea, and the newly assembled genomes and the SVs provide rich resources for future research and breeding.

Fruit Extract Derived from a Mixture of Noni, Pineapple and Mango Capable of Coagulating Milk and Producing Curd with Antidiabetic Activities.

Research background: Morinda citrifolia L. (noni), Ananas comosus L. cv. Sarawak (pineapple) and Mangifera indica L. cv. Apple (mango) represent fruits capable of coagulating milk and forming a curd. Plant-derived milk coagulants have antidiabetic phytochemicals that enrich the curd. Hence this work evaluates the dual benefits of the fruits in coagulating milk and the antidiabetic activities found in the obtained curd. Experimental approach: The three fruits were mixed to form a supercoagulant (a milk coagulant mixture of the extracts at a ratio of 1:1:1), and the milk coagulation time was measured. The milk was coagulated by the supercoagulant, and thus fortified curd was tested for its ability to inhibit α-glucosidase and α-amylase activities. Then, the fortified curd was fed daily to streptozotocin-induced diabetic rats and their biochemical markers such as blood glucose level, aspartate aminotransferase, alanine transaminase, etc. as well as histopathology of their liver and kidney tissues were compared with the untreated diabetic rats and normal rats. Results and conclusion: The supercoagulant had a milk coagulation time of (28±3) s at a 50 mg/mL concentration. Its fortified curd inhibited α-glucosidase and α-amylase activities, with IC50 values of (4.04±0.03) and (3.42±0.02) mg/mL, respectively. The average mass of the streptozotocin-induced diabetic rats fed daily with curd formed by the supercoagulant was (201±10) g on day 20 compared to diabetic control rats with (149±16) g. The blood glucose concentration for rats treated with the supercoagulant after fasting was (15±1) mmol/L compared to the diabetic control rats ((26±2) mmol/L). Blood tests on the treated rats showed aspartate aminotransferase, alanine transaminase, γ-glutamyl transferase and alkaline phosphatase (liver function tests) amounts of (214±78), (91±13), 3 and (510±138) U/L, respectively, while the total protein and renal function tests showed the concentrations of albumin, globulin, urea and creatinine of (37±2) g/L, (30±2) g/L, (11±1) mmol/L and (42±3) µmol/L, respectively. These concentrations were found to be similar to those of the normal rats on day 20. Furthermore, a histopathological study performed on the liver and kidney of the rats found no apparent damage. Novelty and scientific contribution: This supercoagulant derived from a mixture of fruits is able to coagulate milk rapidly, and its curd is fortified with safe antidiabetic agents. The supercoagulant is potentially useful in producing functional dairy food to prevent diabetes or as a supplement for diabetics to control their blood sugar. Such products are capable of replacing dairy products derived from animal enzymes and provide consumers with additional functional dairy products.

A study of lipolysis induced by adjuncts from edible Aspergillus sp. solid culture products on ripened semi-hard cheese.

BACKGROUND: Aspergillus sp. has been used in traditional Japanese fermented foods. Protease-containing culture products of A. oryzae have been applied as the adjunct enzyme source to enrich the flavor in ripened cheese. Although proteolysis was stimulated, the increase of free fatty acids (FFA) was recognized in some products. Since an excess amount of FFA accumulation can cause rancidity in cheese products, the assessment of lipase activity was considered to be essential for the cheese adjunct preparation. RESULTS: Although an equal lipase activity from the adjunct materials of A. kawachii NBRC 4308, A. luchuensis RIB 2604 and A. oryzae AHU 7139 was applied to semi-hard cheese, the FFA level was significantly higher in A. oryzae cheese than in the others. Furthermore, the profiles of volatile components were different in experimental cheeses. An in vitro study with experimental curds demonstrated that the high FFA might not depend on the lipase retainability on curds. On the contrary, the pronounced activation of the lipases occurred in A. oryzae after incubation with the curds. Moreover, incubation of the insoluble lipase that had been attached to the cells with skim milk curd extracts allowed the release of lipases from the cells into the medium with remarkable activation. CONCLUSION: A. oryzae AHU 7139 possessed a complex lipolytic system comprising extracellular and cell-binding lipases that were attributed to the increase in FFA in A. oryzae cheese. © 2022 Society of Chemical Industry.

Food safety research and improvement of the technology of cottage cheese product with the use of green buckwheat.

The purpose of thе article is to study the safety indicators of the curd product, which includes cottage cheese prepared with a starter culture of direct application "Evitalia," consisting of bacteria of the genus Lactococcus (L. acidophilius), Streptococcus (Streptococcus thermophilius) and propionobacteria. Other ingredients are crushed mass from green buckwheat, candied pumpkin, cooked Jerusalem artichoke sirup, and fat emulsion based on coconut oil. The sweetness of the curd product is provided by Jerusalem artichoke sirup, whereas fat emulsion based on coconut oil enriches the product with unsaturated fatty acids and gives plasticity and uniformity of structure. The results of the study showed that the formulation with the following ingredients: 40% of cottage cheese, 40% of crushed mass from green buckwheat, 10% of candied pumpkin, 10% of coconut oil emulsion-has the best organoleptic, physico-chemical, structural and plastic properties. The ratio of milk protein of cottage cheese and vegetable protein of green buckwheat is 1:1. This allowed to obtain the chemical composition of the product: proteins-29%, fats-9%, carbohydrates-59%, ash-3%. The obtained research and technological solutions can be used at dairy industry enterprises in the production of combined dairy and vegetable products.

A novel technique for the preparation of curd (Dahi) by PVDF membrane-based strip.

Preparation of curd at home is quite challenging as it requires skills like addition of proper amount of starter culture, maintenance and storage of inoculum for the preparation of good and consistent quality curd. The present work utilized bacterial attachment property of PVDF (Polyvinylidene fluoride) membrane to prepare a strip which can be dipped into milk for the preparation of consistent quality curd. Shelf-life of the strip is around 100 days. The strip prepared curd was well comparable with the curd prepared by the commercial inoculum based on their pH, % lactic acid, % syneresis and bacterial load. Strip of size 5 × 5 cm2 was enough for preparation of 500 mL curd. It was proved by different analytical techniques like AFM, SEM and FTIR that PVDF was not having any leaching property during curd preparation. It can also be used in repeated contact with food products, as it is FDA (Food and Drug Administration) compliant and non-toxic. The curd strip has significant industrial relevance as it is a cost-effective alternative of any commercial inoculum (very expensive) and also meets the demand of consumers with the rising health awareness and busy lifestyles. Further, it is spillage proof, portable, ready-to-use. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-021-05339-3.

Freezing as a solution to preserve the quality of dairy products: the case of milk, curds and cheese.

When thinking of the freezing process in dairy, products consumed in frozen state, such as ice creams come to mind. However, freezing is also considered a viable solutions for many other dairy products, due to increasing interest to reduce food waste and to create more robust supply chains. Freezing is a solution to production seasonality, or to extend the market reach for high-value products with otherwise short shelf life. This review focuses on the physical and chemical changes occurring during freezing of milk, curds and cheeses, critical to maintaining quality of the final product. However, freezing is energy consuming, and therefore the process needs to be optimized to maintain product's quality and reduce its environmental footprint. Furthermore, the processing steps leading to the freezing stage may require some changes compared to traditional, fresh products. Unwanted reactions occur at low water activity, and during modifications such as ice crystals growth and recrystallization. These events cause major physical destabilizations of the proteins due to cryoconcentration, including modification of the colloidal-soluble equilibrium. The presence of residual proteases and lipases also cause important modifications to the texture and flavor of the frozen dairy product.

Goat farm variability affects milk Fourier-transform infrared spectra used for predicting coagulation properties.

Driven by the large amount of goat milk destined for cheese production, and to pioneer the goat cheese industry, the objective of this study was to assess the effect of farm in predicting goat milk-coagulation and curd-firmness traits via Fourier-transform infrared spectroscopy. Spectra from 452 Sarda goats belonging to 14 farms in central and southeast Sardinia (Italy) were collected. A Bayesian linear regression model was used, estimating all spectral wavelengths' effects simultaneously. Three traditional milk-coagulation properties [rennet coagulation time (min), time to curd firmness of 20 mm (min), and curd firmness 30 min after rennet addition (mm)] and 3 curd-firmness measures modeled over time [rennet coagulation time estimated according to curd firmness change over time (RCTeq), instant curd-firming rate constant, and asymptotical curd firmness] were considered. A stratified cross validation (SCV) was assigned, evaluating each farm separately (validation set; VAL) and keeping the remaining farms to train (calibration set) the statistical model. Moreover, a SCV, where 20% of the goats randomly taken (10 replicates per farm) from the VAL farm entered the calibration set, was also considered (SCV80). To assess model performance, coefficient of determination (R2VAL) and the root mean squared error of validation were recorded. The R2VAL varied between 0.14 and 0.45 (instant curd-firming rate constant and RCTeq, respectively), albeit the standard deviation was approximating half of the mean for all the traits. Although average results of the 2 SCV procedures were similar, in SCV80, the maximum R2VAL increased at about 15% across traits, with the highest observed for time to curd firmness of 20 mm (20%) and the lowest for RCTeq (6%). Further investigation evidenced important variability among farms, with R2VAL for some of them being close to 0. Our work outlined the importance of considering the effect of farm when developing Fourier-transform infrared spectroscopy prediction equations for coagulation and curd-firmness traits in goats.

Breed of goat affects the prediction accuracy of milk coagulation properties using Fourier-transform infrared spectroscopy.

The prediction of traditional goat milk coagulation properties (MCP) and curd firmness over time (CFt) parameters via Fourier-transform infrared (FTIR) spectroscopy can be of significant economic interest to the dairy industry and can contribute to the breeding objectives for the genetic improvement of dairy goat breeds. Therefore, the aims of this study were to (1) explore the variability of milk FTIR spectra from 4 goat breeds (Camosciata delle Alpi, Murciano-Granadina, Maltese, and Sarda), and to assess the possible discriminant power of milk FTIR spectra among breeds, (2) assess the viability to predict coagulation traits by using milk FTIR spectra, and (3) quantify the effect of the breed on the prediction accuracy of MCP and CFt parameters. In total, 611 individual goat milk samples were used. Analysis of variance of measured MCP and CFt parameters was carried out using a mixed model including the farm and pendulum as random factors, and breed, parity, and days in milk as fixed factors. Milk spectra for each goat were collected over the spectral range from wavenumber 5,011 to 925 × cm-1. Discriminant analysis of principal components was used to assess the ability of FTIR spectra to identify breed of origin. A Bayesian model was used to calibrate equations for each coagulation trait. The accuracy of the model and the prediction equation was assessed by cross-validation (CRV; 80% training and 20% testing set) and stratified CRV (SCV; 3 breeds in the training set, one breed in the testing set) procedures. Prediction accuracy was assessed by using coefficient of determination of validation (R2VAL), the root mean square error of validation (RMSEVAL), and the ratio performance deviation. Moreover, measured and FTIR predicted traits were compared in the SCV procedure by assessing their least squares means for the breed effect, Pearson correlations, and variance heteroscedasticity. Results showed the feasibility of using FTIR spectra and multivariate analyses to correctly assign milk samples to their breeds of origin. The R2VAL values obtained with the CRV procedure were moderate to high for the majority of coagulation traits, with RMSEVAL and ratio performance deviation values increasing as the coagulation process progresses from rennet addition. Prediction accuracy obtained with the SCV were strongly influenced by the breed, presenting general low values restricting a practical application. In addition, the low Pearson correlation coefficients of Sarda breed for all the traits analyzed, and the heteroscedastic variances of Camosciata delle Alpi, Murciano-Granadina, and Maltese breeds, further indicated that it is fundamental to consider the differences existing among breeds for the prediction of milk coagulation traits.

Derivation of multivariate indices of milk composition, coagulation properties, and curd yield in Manchega dairy sheep.

This study approaches the interrelation patterns between composition of milk and whey, curd yield, chromaticity, syneresis, and technological quality of Manchega sheep milk using multivariate factor analysis. In addition, the effect of the main husbandry components (flock, prolificacy, season of the year, stage of lactation, and parity) on the common latent factors that define the pattern of variation of Manchega milk was assessed. For this purpose, 1,200 individual Manchega ewe milk samples from 4 different flocks registered under the Protected Designation of Origin Queso Manchego were analyzed (50 ewes/flock). Samples were collected in 2 different seasons of the year (spring and autumn) and at 3 time points per season: early, mid-, and late lactation. The obtained results suggested that curd yield mainly depends on milk composition, and the retention of water in the curd is related to coagulation traits. Thus, composition and moisture content could be useful indicators to assess the efficiency and quality of milk intended for cheesemaking, regardless of the analysis of coagulation properties. Finally, in terms of husbandry, a direct effect of flock and stage of lactation was observed on all analyzed factors, with a lower influence of season and parity.