Application of chromatographic and spectroscopic techniques in the evaluation of the lipid fraction of animal products

Lipolysis and oxidation of lipids in foods are the major biochemical and chemical processes that cause food quality deterioration, leading to the characteristic, unpalatable odour and flavour called rancidity. In addition to unpalatability, rancidity may give rise to toxic levels of certain compounds like aldehydes, hydroperoxides, epoxides and cholesterol oxidation products. In this PhD study chromatographic and spectroscopic techniques were employed to determine the degree of rancidity in different animal products and its relationship with technological parameters like feeding fat sources, packaging, processing and storage conditions. To achieve this goal capillary gas chromatography (CGC) was employed not only to determine the fatty acids profile but also, after solid phase extraction, the amount of free fatty acids (FFA), diglycerides (DG), sterols (cholesterol and phytosterols) and cholesterol oxidation products (COPs). To determine hydroperoxides, primary products of oxidation and quantify secondary products UV/VIS absorbance spectroscopy was applied. Most of the foods analysed in this study were meat products. In actual fact, lipid oxidation is a major deterioration reaction in meat and meat products and results in adverse changes in the colour, flavour and texture of meat. The development of rancidity has long recognized as a serious problem during meat handling, storage and processing. On a dairy product, a vegetal cream, a study of lipid fraction and development of rancidity during storage was carried out to evaluate its shelf-life and some nutritional features life saturated/unsaturated fatty acids ratio and phytosterols content. Then, according to the interest that has been growing around functional food in the last years, a new electrophoretic method was optimized and compared with HPLC to check the quality of a beehive product like royal jelly. This manuscript reports the main results obtained in the five activities briefly summarized as follows: 1) comparison between HPLC and a new electrophoretic method in the evaluation of authenticity of royal jelly; 2) study of the lipid fraction of a vegetal cream under different storage conditions; 3) study of lipid oxidation in minced beef during storage under a modified atmosphere packaging, before and after cooking; 4) evaluation of the influence of dietary fat and processing on the lipid fraction of chicken patties; 5) study of the lipid fraction of typical Italian and Spanish pork dry sausages and cured hams.

Application of different instrumental techniques to the selective evaluation of bio-sensible compounds in foodstuff of animal and vegetable origin

This PhD thesis describes the application of some instrumental analytical techniques suitable to the study of fundamental food products for the human diet, such as: extra virgin olive oil and dairy products. These products, widely spread in the market and with high nutritional values, are increasingly recognized healthy properties although their lipid fraction might contain some unfavorable components to the human health. The research activity has been structured in the following investigations: “Comparison of different techniques for trans fatty acids analysis” “Fatty acids analysis of outcrop milk cream samples, with particular emphasis on the content of Conjugated Linoleic Acid (CLA) and trans Fatty Acids (TFA), by using 100m high-polarity capillary column” “Evaluation of the oxidited fatty acids (OFA) content during the Parmigiano-Reggiano cheese seasoning” “Direct analysis of 4-desmethyl sterols and two dihydroxy triterpenes in saponified vegetal oils (olive oil and others) using liquid chromatography-mass spectrometry” “Quantitation of long chain poly-unsatured fatty acids (LC-PUFA) in base infant formulas by Gas Chromatography, and evaluation of the blending phases accuracy during their preparation” “Fatty acids composition of Parmigiano Reggiano cheese samples, with emphasis on trans isomers (TFA)”

Effetto della temperatura di conservazione del latte, dalla raccolta all'affioramento, sulla microflora del latte, del sieroinnesto e del formaggio Trentingrana

This PhD research is part of a project addressed to improve the quality of Grana Trentino production. The objectives were to evaluated if milk storage and collection procedures may affect cheese-making technology and quality. Actually the milk is collected and delivered to the cheese factory just after milking in 50 L cans without refrigeration or in tanks cooled at 18 °C. This procedure is expensive (two deliveries each day) and the milk quality is difficult to preserve as temperatures are not controlled. The milk refrigeration at the farm could allow a single delivery to the dairy. Therefore it could be a good strategy to preserve raw milk quality and reduce cheese spoilage. This operation may, however, have the drawbacks of favouring the growth of psychrotrophic bacteria and changing the aptitude of milk to coagulation. With the aim of studying the effect on milk and cheese of traditional and new refrigerated technologies of milk storage, two different collection and creaming technologies were compared. The trials were replicated in three cheese factories manufacturing Grana Trentino. Every cheese-making day, about 1000 milk liters were collected from always the same two farms in the different collection procedures (single or double). Milk was processed to produce 2 wheels of Grana trentino every day. During the refrigerated trials, milk was collected and stored at the farm in a mixed tank at 12 or 8 °C and then was carried to the dairy in truck once a day. 112 cheese making day were followed: 56 for traditional technology and 56 for the refrigerated one. Each one of these two thechnologies lead to different ways of creaming: long time in the traditional one and shorter in the new one. For every cheese making day we recorded time, temperatures and pH during the milk processing to cheese. Whole milk before ceraming, cream and skim milk after creaming, vat milk and whey were sampled during every cheese-making day for analysis. After 18 months ripening we opened 46 cheese wheels for further chemical and microbiological analyses. The trials were performed with the aim of: 1 estimate the effect of storage temperatures on microbial communities, physico-chemical or/and rheological differences of milk and skim milk after creaming. 2 detect by culture dependent (plate counts) and indipendent (DGGE) methodolgies the microbial species present in whole, skimmed milk, cream and cheese sampled under the rind and in the core; 3 estimate the physico-chemical characteristics, the proteolytic activity, the content of free aminoacids and volatile compounds in 18 months ripened Grana Trentino cheeses from different storing and creaming of milk technologies. The results presented are remarkable since this is the first in-deep study presenting microbiological and chemical analysis of Grana Trentino that even if belonging to Grana Padano Consortium, it is clearly different in the milk and in the manufacturing technology.

Applicazioni industriali e di ricerca della spettroscopia NIR per la valutazione di indici qualitativi di prodotti alimentari

In the present work qualitative aspects of products that fall outside the classic Italian of food production view will be investigated, except for the apricot, a fruit, however, less studied by the methods considered here. The development of computer systems and the advanced software systems dedicated for statistical processing of data, has permitted the application of advanced technologies including the analysis of niche products. The near-infrared spectroscopic analysis was applied to the chemical industry for over twenty years and, subsequently, was applied in food industry with great success for non-destructive in line and off-line analysis. The work that will be presented below range from the use of spectroscopy for the determination of some rheological indices of ice cream applications to the characterization of the main quality indices of apricots, fresh dates, determination of the production areas of pistachio. Next to the spectroscopy will be illustrated different methods of multivariate analysis for spectra interpretation or for the construction of qualitative models of estimation. The thesis is divided into four separate studies that consider the same number of products. Each one of it is introduced by its own premise and ended with its own bibliography. This studies are preceded by a general discussion on the state of art and the basics of NIR spectroscopy.

Nuovi ingredienti funzionali per l'applicazione in campo alimentare

The Mediterranean diet is rich in healthy substances such as fibres, vitamins and phenols. Often these molecules are lost during food processing. Olive oil milling waste waters, brans, grape skins are some of the most relevant agri-food by-products in the Mediterranean countries. These wastes are still rich in extremely valuable molecules, such as phenolic antioxidants, that have several interesting health promoting properties. Using innovative environmental friendly technologies based in the rational use of enzymatic treatment is possible to obtain from agri-food by-products new ingredients containing antioxidants that can be used as functional ingredients in order to produce fortified foods. These foods, having health protecting/promoting properties, on top of the traditional nutritional properties, are attracting consumer’s attentions due to the increasing awareness on health protection through prevention. The use of these new ingredients in different food preparation was studied in order to evaluate the effects that the food processing might have on the antioxidant fraction, the effect of these ingredient on foods appearances as well as the impact in terms of taste and scent, crucial feature for the acceptability of the final product. Using these new ingredients was possible to produce antioxidant bred, pasta, cheese, cookies and ice-cream. These food products retains very well the antioxidant properties conferred by the added ingredients despite the very different treatments that were performed. The food obtained had a good palatability and in some cases the final product had also a good success on the market.