Synthetic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) have been used widely for many years to retard lipid oxidation. Concern about the safety of synthetic antioxidants together with consumer preference for natural products has resulted in increased research on natural antioxidants. Many spices have been shown to impart an antioxidative effect in foods. This article summarizes the literature on the antioxidative effects of spices. The term spice is defined as dry plant material that is normally added to food to impart flavour.

Spices as antioxidants

Turmeric is a minor spice in the West, but a major one in the East. It is valued by Westerners mainly, if not solely, on account of its color, but to the Asians both color and aroma are equally important. This review critically appraises the existing knowledge on the chemistry of the functionally important constituents, the processing of the spice into wholes, powder, and oleoresins, and the objective methods and standards available for evaluation of quality. The importance of the mild (but persistent) aroma, and the lack of detailed knowledge on the significant volatiles are discussed. Some unpublished data on significant aroma components, a tristimulus study of color, and subjective evaluations of quality are summarized. Other areas briefly discussed are the production and trade, curry powder, allied spices, and biosynthetic and physiological aspects. The confusion existing in the literature on the nomenclature of species included in the genus Curcuma is pointed out. In view of the growing importance of turmeric and its extracts as a natural food color, recent results on toxicological aspects are discussed. The areas in which research is needed are indicated at the end.

Turmeric — chemistry, technology, and quality

A Review of Cyclopropenoid Compounds: Biological Effects of Some Derivatives

Publisher Summary This chapter is concerned with two types of oxidative changes that occur in meat: oxidation of the fat, resulting in rancidity; and oxidation of the heme pigments, resulting in discoloration. The two are closely related. In fact, each can accelerate the other, but each can also proceed independently of the other. Together they account for a large part of the economic loss due to substandard or spoiled meat. The chapter devotes to the more fundamental work on these reactions and their interrelationships in meat as it is believed that control can best be achieved when the causes of deterioration are thoroughly understood. In general, the oxidative changes discussed are those of chemical rather than microbiological origin, although it is recognized that the same changes are often brought about by bacteria, and it is not always possible to determine whether bacteria are implicated. The chapter presents facts that contradict simple assumptions such as the idea that the fresh meat of any species is a more or less uniform starting point for experimentation and the idea that the various oxidations that occur in meat, resulting in off-odors, off-flavors, and discolorations, could be lumped together for purposes of control.

Oxidative rancidity and discoloration in meat.

Occurrence of unusual fatty acids in plants

THE structure of sterculic acid, the major component of the kernel oil of Sterculia foetida, has attracted the attention of various workers. Hilditch et al.
1 failed to isolate the acid but concluded from the constants of the oil and the mixed methyl esters and some degradative experiments that it was 12-methyl octadeca-9: 11-dienoic acid. Steger and Van Loon2, working on the mixed fatty acids, deduced that it was probably a hydroxy acid, C18H34O3. However, recently Nunn3 has isolated this acid, C19H34O2, by the method of urea complexes and suggested its structure as ω -(2n-octylcycloprop-1-enyl)-octanoic acid (I).

Structure of Sterculic Acid

Sterculia foetida oil has been found to contain 71.8% of sterculic acid and minor proportions of oleic, linoleic, and saturated acids. The saturated component consists mostly of myristic and palmitic acids.

Composition of the seed oil of sterculia foetida, Linn

FORTIFICATION of edible oils and fats against oxidation and rancidity is essential from the point of view of smell, taste and colour of the materials; further, oxidized and rancid oils have injurious physiological effects on the human system. For human consumption, refined oils are generally used; but they lose their natural antioxidants during processing. A difficulty in stabilizing edible fats is that, except for a few substances such as N.D.G.A., lecithin, tocopherols, kamla dye and oat flour, most antioxidants are toxic. N.D.G.A. is very sparingly soluble in oils and kamla dyes fat orange.

Stabilization of Edible Fats by Condiments or Spices

a)

A series of methyl esters of fatty acids were reacted with N-bromosuccinimide, and the products were dehydrobrominated by heating.




b)

In the reaction of metyyl erucate and methyl oleate with equivalent amounts of N-bromosuccinimide, bromination occurred in the allylic position farthest from the carboxyl group. Products of dehydrobromination contained 30–40% conjugated dienoic acids.




c)

Use of excess N-bromosuccinimide led to production of both diene and triene conjugation.




d)

Products from mono-acetylenic fatty acids had a double bond conjugated to the triple bond initially present.




e)

The product from methyl 9∶12-linoleate was a complex mixture having diene, triene, and tetraene conjugation.




f)

Mustard seed, peanut, olive, karanja, neem, tobacco seed, and safflower oils were reacted with N-bromosuccinimide. The bromo derivatives could not be satisfactorily dehydrobrominated by heat alone; heating in pyridine, quinoline, or 2∶4∶6-collidine was more effective. The products from safflower and tobacco seed oils partially gelled during the process. The films of all the treated oils dried in wrinkled patterns.

J. S. Aggarwal

Papers

Structure of Sterculic Acid

Composition of the seed oil of sterculia foetida, Linn

Stabilization of Edible Fats by Condiments or Spices

N‐bromosuccinimide in the conjugation of fatty acids and oils